[release-branch.go1.8] go1.8.7

Change-Id: Ida9b4f44033f33657dad213f65b0c85ad89b08a7
Reviewed-on: https://team-review.git.corp.google.com/213169
Reviewed-by: Andrew Bonventre <andybons@google.com>

VERSION

@@ -1 +1 @@
-go1.8.3.typealias
+go1.8.7

doc/devel/release.html

@@ -63,6 +63,36 @@ See the <a href="https://github.com/golang/go/issues?q=milestone%3AGo1.8.3">Go
 1.8.3 milestone</a> on our issue tracker for details.
 </p>
 
+<p>
+go1.8.4 (released 2017/10/04) includes two security fixes.
+It contains the same fixes as Go 1.9.1 and was released at the same time.
+See the <a href="https://github.com/golang/go/issues?q=milestone%3AGo1.8.4">Go
+1.8.4 milestone</a> on our issue tracker for details.
+</p>
+
+<p>
+go1.8.5 (released 2017/10/25) includes fixes to the compiler, linker, runtime,
+documentation, <code>go</code> command,
+and the <code>crypto/x509</code> and <code>net/smtp</code> packages.
+It includes a fix to a bug introduced in Go 1.8.4 that broke <code>go</code> <code>get</code>
+of non-Git repositories under certain conditions.
+See the <a href="https://github.com/golang/go/issues?q=milestone%3AGo1.8.5">Go
+1.8.5 milestone</a> on our issue tracker for details.
+</p>
+
+<p>
+go1.8.6 (released 2018/01/22) includes the the same fix in <code>math/big</code>
+as Go 1.9.3 and was released at the same time.
+See the <a href="https://github.com/golang/go/issues?q=milestone%3AGo1.8.6">Go
+1.8.6 milestone</a> on our issue tracker for details.
+</p>
+
+<p>
+go1.8.7 (released 2018/02/07) includes a security fix to “go get”.
+See the <a href="https://github.com/golang/go/issues?q=milestone%3AGo1.8.7">Go
+1.8.7</a> milestone on our issue tracker for details.
+</p>
+
 <h2 id="go1.7">go1.7 (released 2016/08/15)</h2>
 
 <p>

doc/go1.8.txt

@@ -1,55 +0,0 @@
-This file lists things yet to be moved into go1.8.html or deemed too
-minor to mention. Either way, delete from here when done.
-
-Tools:
-
-go: -buildmode=c-archive now builds PIC on ELF (CL 24180)
-go: mobile pkg dir change, recommend using go list in scripts (CL 24930, CL 27929)
-go, dist: can set default pkg-config tool using PKG_CONFIG env var (CL 29991)
-go: can set secure/insecure GIT schemes using GIT_ALLOW_PROTOCOL env var (CL 30135)
-
-API additions and behavior changes:
-
-cmd/compile, runtime, etc: get rid of constant FP registers (CL 28095)
-cmd/compile, runtime: add go:yeswritebarrierrec pragma (CL 30938)
-cmd/compile/internal/gc: enable new parser by default (CL 27203)
-cmd/compile/internal/syntax: fast Go syntax trees, initial commit (CL 27195)
-cmd/compile: add compiler phase timing (CL 24462)
-cmd/compile: add inline explainer (CL 22782)
-cmd/compile: enable flag-specified dump of specific phase+function (CL 23044)
-
-cmd/internal/obj, cmd/link: darwin dynlink support (CL 29393)
-cmd/internal/objfile: add ppc64/ppc64le disassembler support (CL 9682)
-cmd/link, cmd/go: delay linking of mingwex and mingw32 until very end (CL 26670)
-cmd/link: R_ADDR dynamic relocs for internal PIE (CL 29118)
-cmd/link: add trampolines for too far calls in ppc64x (CL 30850)
-cmd/link: allow internal PIE linking (CL 28543)
-cmd/link: fix -X importpath.name=value when import path needs escaping (CL 31970)
-cmd/link: fix -buildmode=pie / -linkshared combination (CL 28996)
-cmd/link: for -buildmode=exe pass -no-pie to external linker (CL 33106)
-cmd/link: insert trampolines for too-far jumps on ARM (CL 29397)
-cmd/link: non-executable stack support for Solaris (CL 24142)
-cmd/link: put text at address 0x1000000 on darwin/amd64 (CL 32185)
-cmd/link: remove the -shared flag (CL 28852)
-cmd/link: split large elf text sections on ppc64x (CL 27790)
-cmd/link: trampoline support for external linking on ARM (CL 31143)
-cmd/objdump: implement objdump of .o files (CL 24818)
-
-go/build: allow % in ${SRCDIR} expansion for Jenkins (CL 31611)
-go/build: do not record go:binary-only-package if build tags not satisfied (CL 31577)
-go/build: implement default GOPATH (CL 32019)
-
-runtime/race: update race runtime (CL 32160)
-runtime: assume 64kB physical pages on ARM (CL 25021)
-runtime: disable stack rescanning by default (CL 31766)
-runtime: don't call cgocallback from signal handler (CL 30218)
-runtime: fix check for vacuous page boundary rounding (CL 27230)
-runtime: fix map iterator concurrent map check (CL 24749)
-runtime: fix newextram PC passed to race detector (CL 29712)
-runtime: implement unconditional hybrid barrier (CL 31765)
-runtime: include pre-panic/throw logs in core dumps (CL 32013)
-runtime: limit the number of map overflow buckets (CL 25049)
-runtime: pass windows float syscall args via XMM (CL 32173)
-runtime: print sigcode on signal crash (CL 32183)
-runtime: record current PC for SIGPROF on non-Go thread (CL 30252)
-runtime: sleep on CLOCK_MONOTONIC in futexsleep1 on freebsd (CL 30154)

doc/go_spec.html

@@ -1,6 +1,6 @@
 <!--{
 	"Title": "The Go Programming Language Specification",
-	"Subtitle": "Version of January 31, 2017",
+	"Subtitle": "Version of November 18, 2016",
 	"Path": "/ref/spec"
 }-->
 
@@ -738,7 +738,7 @@ The method set of any other type <code>T</code> consists of all
 The method set of the corresponding <a href="#Pointer_types">pointer type</a> <code>*T</code>
 is the set of all methods declared with receiver <code>*T</code> or <code>T</code>
 (that is, it also contains the method set of <code>T</code>).
-Further rules apply to structs containing embedded fields, as described
+Further rules apply to structs containing anonymous fields, as described
 in the section on <a href="#Struct_types">struct types</a>.
 Any other type has an empty method set.
 In a method set, each method must have a
@@ -947,16 +947,16 @@ Moreover, the inner slices must be initialized individually.
 <p>
 A struct is a sequence of named elements, called fields, each of which has a
 name and a type. Field names may be specified explicitly (IdentifierList) or
-implicitly (EmbeddedField).
+implicitly (AnonymousField).
 Within a struct, non-<a href="#Blank_identifier">blank</a> field names must
 be <a href="#Uniqueness_of_identifiers">unique</a>.
 </p>
 
 <pre class="ebnf">
-StructType    = "struct" "{" { FieldDecl ";" } "}" .
-FieldDecl     = (IdentifierList Type | EmbeddedField) [ Tag ] .
-EmbeddedField = [ "*" ] TypeName .
-Tag           = string_lit .
+StructType     = "struct" "{" { FieldDecl ";" } "}" .
+FieldDecl      = (IdentifierList Type | AnonymousField) [ Tag ] .
+AnonymousField = [ "*" ] TypeName .
+Tag            = string_lit .
 </pre>
 
 <pre>
@@ -974,15 +974,16 @@ struct {
 </pre>
 
 <p>
-A field declared with a type but no explicit field name is called an <i>embedded field</i>.
-An embedded field must be specified as
+A field declared with a type but no explicit field name is an <i>anonymous field</i>,
+also called an <i>embedded</i> field or an embedding of the type in the struct.
+An embedded type must be specified as
 a type name <code>T</code> or as a pointer to a non-interface type name <code>*T</code>,
 and <code>T</code> itself may not be
 a pointer type. The unqualified type name acts as the field name.
 </p>
 
 <pre>
-// A struct with four embedded fields of types T1, *T2, P.T3 and *P.T4
+// A struct with four anonymous fields of type T1, *T2, P.T3 and *P.T4
 struct {
 	T1        // field name is T1
 	*T2       // field name is T2
@@ -999,15 +1000,15 @@ in a struct type:
 
 <pre>
 struct {
-	T     // conflicts with embedded field *T and *P.T
-	*T    // conflicts with embedded field T and *P.T
-	*P.T  // conflicts with embedded field T and *T
+	T     // conflicts with anonymous field *T and *P.T
+	*T    // conflicts with anonymous field T and *P.T
+	*P.T  // conflicts with anonymous field T and *T
 }
 </pre>
 
 <p>
 A field or <a href="#Method_declarations">method</a> <code>f</code> of an
-embedded field in a struct <code>x</code> is called <i>promoted</i> if
+anonymous field in a struct <code>x</code> is called <i>promoted</i> if
 <code>x.f</code> is a legal <a href="#Selectors">selector</a> that denotes
 that field or method <code>f</code>.
 </p>
@@ -1024,7 +1025,7 @@ promoted methods are included in the method set of the struct as follows:
 </p>
 <ul>
 	<li>
-	If <code>S</code> contains an embedded field <code>T</code>,
+	If <code>S</code> contains an anonymous field <code>T</code>,
 	the <a href="#Method_sets">method sets</a> of <code>S</code>
 	and <code>*S</code> both include promoted methods with receiver
 	<code>T</code>. The method set of <code>*S</code> also
@@ -1032,7 +1033,7 @@ promoted methods are included in the method set of the struct as follows:
 	</li>
 
 	<li>
-	If <code>S</code> contains an embedded field <code>*T</code>,
+	If <code>S</code> contains an anonymous field <code>*T</code>,
 	the method sets of <code>S</code> and <code>*S</code> both
 	include promoted methods with receiver <code>T</code> or
 	<code>*T</code>.
@@ -1433,8 +1434,8 @@ literal structure and corresponding components have identical types. In detail:
 	<li>Two struct types are identical if they have the same sequence of fields,
 	    and if corresponding fields have the same names, and identical types,
 	    and identical tags.
-	    <a href="#Exported_identifiers">Non-exported</a> field names from different
-	    packages are always different.</li>
+	    Two anonymous fields are considered to have the same name. Lower-case field
+	    names from different packages are always different.</li>
 
 	<li>Two pointer types are identical if they have identical base types.</li>
 
@@ -1444,9 +1445,8 @@ literal structure and corresponding components have identical types. In detail:
 	    Parameter and result names are not required to match.</li>
 
 	<li>Two interface types are identical if they have the same set of methods
-	    with the same names and identical function types.
-	    <a href="#Exported_identifiers">Non-exported</a> method names from different
-	    packages are always different. The order of the methods is irrelevant.</li>
+	    with the same names and identical function types. Lower-case method names from
+	    different packages are always different. The order of the methods is irrelevant.</li>
 
 	<li>Two map types are identical if they have identical key and value types.</li>
 
@@ -1891,7 +1891,7 @@ type NewMutex Mutex
 type PtrMutex *Mutex
 
 // The method set of *PrintableMutex contains the methods
-// Lock and Unlock bound to its embedded field Mutex.
+// Lock and Unlock bound to its anonymous field Mutex.
 type PrintableMutex struct {
 	Mutex
 }
@@ -2492,13 +2492,13 @@ If <code>x</code> is a package name, see the section on
 A selector <code>f</code> may denote a field or method <code>f</code> of
 a type <code>T</code>, or it may refer
 to a field or method <code>f</code> of a nested
-<a href="#Struct_types">embedded field</a> of <code>T</code>.
-The number of embedded fields traversed
+<a href="#Struct_types">anonymous field</a> of <code>T</code>.
+The number of anonymous fields traversed
 to reach <code>f</code> is called its <i>depth</i> in <code>T</code>.
 The depth of a field or method <code>f</code>
 declared in <code>T</code> is zero.
 The depth of a field or method <code>f</code> declared in
-an embedded field <code>A</code> in <code>T</code> is the
+an anonymous field <code>A</code> in <code>T</code> is the
 depth of <code>f</code> in <code>A</code> plus one.
 </p>
 

doc/install-source.html

@@ -143,7 +143,7 @@ packaged Go distribution.
 <p>
 To build a bootstrap tool chain from source, use
 either the git branch <code>release-branch.go1.4</code> or
-<a href="https://storage.googleapis.com/golang/go1.4-bootstrap-20161024.tar.gz">go1.4-bootstrap-20161024.tar.gz</a>,
+<a href="https://storage.googleapis.com/golang/go1.4-bootstrap-20170531.tar.gz">go1.4-bootstrap-20170531.tar.gz</a>,
 which contains the Go 1.4 source code plus accumulated fixes
 to keep the tools running on newer operating systems.
 (Go 1.4 was the last distribution in which the tool chain was written in C.)

doc/root.html

@@ -6,7 +6,9 @@
 <div class="left">
 
 <div id="learn">
+{{if not $.GoogleCN}}
 <a class="popout share">Pop-out</a>
+{{end}}
 <div class="rootHeading">Try Go</div>
 <div class="input">
 <textarea spellcheck="false" class="code">// You can edit this code!
@@ -26,10 +28,10 @@ Hello, 世界
 </div>
 <div class="buttons">
 <a class="run" href="#" title="Run this code [shift-enter]">Run</a>
-{{if $.Share}}
+{{if not $.GoogleCN}}
 <a class="share" href="#" title="Share this code">Share</a>
-{{end}}
 <a class="tour" href="//tour.golang.org/" title="Learn Go from your browser">Tour</a>
+{{end}}
 </div>
 <div class="toys">
 <select>
@@ -68,85 +70,91 @@ Linux, Mac OS X, Windows, and more.
 
 <div style="clear: both"></div>
 
+{{if not $.GoogleCN}}
 <div class="left">
-
-<div id="video">
-<div class="rootHeading">Featured video</div>
-<iframe width="415" height="241" src="//www.youtube.com/embed/ytEkHepK08c" frameborder="0" allowfullscreen></iframe>
-</div>
-
+  <div id="video">
+    <div class="rootHeading">Featured video</div>
+    <iframe width="415" height="241" src="//www.youtube.com/embed/ytEkHepK08c" frameborder="0" allowfullscreen></iframe>
+  </div>
 </div>
 
 <div class="right">
-
-<div id="blog">
-<div class="rootHeading">Featured articles</div>
-<div class="read"><a href="//blog.golang.org/">Read more</a></div>
-</div>
-
+	<div id="blog">
+		<div class="rootHeading">Featured articles</div>
+		<div class="read"><a href="//blog.golang.org/">Read more</a></div>
+	</div>
 </div>
+{{end}}
 
 <div style="clear: both;"></div>
 
-<script type="text/javascript">
+<script>
+(function() {
+	'use strict';
 
-function readableTime(t) {
-	var m = ["January", "February", "March", "April", "May", "June", "July",
-		"August", "September", "October", "November", "December"];
-	var p = t.substring(0, t.indexOf("T")).split("-");
-	var d = new Date(p[0], p[1]-1, p[2]);
-	return d.getDate() + " " + m[d.getMonth()] + " " + d.getFullYear();
-}
+	window.initFuncs.push(function() {
+		// Set up playground if enabled.
+		if (window.playground) {
+			window.playground({
+				"codeEl":        "#learn .code",
+				"outputEl":      "#learn .output",
+				"runEl":         "#learn .run",
+				"shareEl":       "#learn .share",
+				"shareRedirect": "//play.golang.org/p/",
+				"toysEl":        "#learn .toys select"
+			});
+		} else {
+			$('#learn').hide()
+		}
+	});
 
-function feedLoaded(result) {
-	var blog = document.getElementById("blog");
-	var read = blog.getElementsByClassName("read")[0];
-	for (var i = 0; i < result.length && i < 2; i++) {
-		var entry = result[i];
-		var title = document.createElement("a");
-		title.className = "title";
-		title.href = entry.Link;
-		title.innerHTML = entry.Title;
-		blog.insertBefore(title, read);
-		var extract = document.createElement("div");
-		extract.className = "extract";
-		extract.innerHTML = entry.Summary;
-		blog.insertBefore(extract, read);
-		var when = document.createElement("div");
-		when.className = "when";
-		when.innerHTML = "Published " + readableTime(entry.Time);
-		blog.insertBefore(when, read);
-	}
-}
+	{{if not $.GoogleCN}}
 
-window.initFuncs.push(function() {
-	// Set up playground if enabled.
-	if (window.playground) {
-		window.playground({
-			"codeEl":        "#learn .code",
-			"outputEl":      "#learn .output",
-			"runEl":         "#learn .run",
-			"shareEl":       "#learn .share",
-			"shareRedirect": "//play.golang.org/p/",
-			"toysEl":        "#learn .toys select"
-		});
-	} else {
-		$('#learn').hide()
+	function readableTime(t) {
+		var m = ["January", "February", "March", "April", "May", "June", "July",
+			"August", "September", "October", "November", "December"];
+		var p = t.substring(0, t.indexOf("T")).split("-");
+		var d = new Date(p[0], p[1]-1, p[2]);
+		return d.getDate() + " " + m[d.getMonth()] + " " + d.getFullYear();
 	}
 
-	// Load blog feed.
-	$('<script/>').attr('text', 'text/javascript')
-		.attr('src', '//blog.golang.org/.json?jsonp=feedLoaded')
-		.appendTo('body');
+	window.feedLoaded = function(result) {
+		var blog = document.getElementById("blog");
+		var read = blog.getElementsByClassName("read")[0];
+		for (var i = 0; i < result.length && i < 2; i++) {
+			var entry = result[i];
+			var title = document.createElement("a");
+			title.className = "title";
+			title.href = entry.Link;
+			title.innerHTML = entry.Title;
+			blog.insertBefore(title, read);
+			var extract = document.createElement("div");
+			extract.className = "extract";
+			extract.innerHTML = entry.Summary;
+			blog.insertBefore(extract, read);
+			var when = document.createElement("div");
+			when.className = "when";
+			when.innerHTML = "Published " + readableTime(entry.Time);
+			blog.insertBefore(when, read);
+		}
+	}
 
-	// Set the video at random.
-	var videos = [
-		{h: 241, s: "//www.youtube.com/embed/ytEkHepK08c"}, // Tour of Go
-		{h: 241, s: "//www.youtube.com/embed/f6kdp27TYZs"}, // Concurrency Patterns
-		{h: 233, s: "//player.vimeo.com/video/69237265"}    // Simple environment
-	];
-	var v = videos[Math.floor(Math.random()*videos.length)];
-	$('#video iframe').attr('height', v.h).attr('src', v.s);
-});
+	window.initFuncs.push(function() {
+		// Load blog feed.
+		$('<script/>').attr('text', 'text/javascript')
+			.attr('src', '//blog.golang.org/.json?jsonp=feedLoaded')
+			.appendTo('body');
 
+		// Set the video at random.
+		var videos = [
+			{h: 241, s: "//www.youtube.com/embed/ytEkHepK08c"}, // Tour of Go
+			{h: 241, s: "//www.youtube.com/embed/f6kdp27TYZs"}, // Concurrency Patterns
+			{h: 233, s: "//player.vimeo.com/video/69237265"}    // Simple environment
+		];
+		var v = videos[Math.floor(Math.random()*videos.length)];
+		$('#video iframe').attr('height', v.h).attr('src', v.s);
+	});
+
+	{{end}}
+})();
 </script>

misc/cgo/errors/err1.go

@@ -5,7 +5,7 @@
 package main
 
 /*
-#cgo LDFLAGS: -c
+#cgo LDFLAGS: -L/nonexist
 
 void test() {
 	xxx;		// ERROR HERE

src/cmd/cgo/doc.go

@@ -55,11 +55,21 @@ For example:
 
 The default pkg-config tool may be changed by setting the PKG_CONFIG environment variable.
 
+For security reasons, only a limited set of flags are allowed, notably -D, -I, and -l.
+To allow additional flags, set CGO_CFLAGS_ALLOW to a regular expression
+matching the new flags. To disallow flags that would otherwise be allowed,
+set CGO_CFLAGS_DISALLOW to a regular expression matching arguments
+that must be disallowed. In both cases the regular expression must match
+a full argument: to allow -mfoo=bar, use CGO_CFLAGS_ALLOW='-mfoo.*',
+not just CGO_CFLAGS_ALLOW='-mfoo'. Similarly named variables control
+the allowed CPPFLAGS, CXXFLAGS, FFLAGS, and LDFLAGS.
+
 When building, the CGO_CFLAGS, CGO_CPPFLAGS, CGO_CXXFLAGS, CGO_FFLAGS and
 CGO_LDFLAGS environment variables are added to the flags derived from
 these directives.  Package-specific flags should be set using the
 directives, not the environment variables, so that builds work in
-unmodified environments.
+unmodified environments. Flags obtained from environment variables
+are not subject to the security limitations described above.
 
 All the cgo CPPFLAGS and CFLAGS directives in a package are concatenated and
 used to compile C files in that package.  All the CPPFLAGS and CXXFLAGS

src/cmd/compile/internal/gc/align.go

@@ -74,13 +74,7 @@ func widstruct(errtype *Type, t *Type, o int64, flag int) int64 {
 			lastzero = o
 		}
 		o += w
-		maxwidth := Thearch.MAXWIDTH
-		// On 32-bit systems, reflect tables impose an additional constraint
-		// that each field start offset must fit in 31 bits.
-		if maxwidth < 1<<32 {
-			maxwidth = 1<<31 - 1
-		}
-		if o >= maxwidth {
+		if o >= Thearch.MAXWIDTH {
 			yyerror("type %L too large", errtype)
 			o = 8 // small but nonzero
 		}

src/cmd/compile/internal/gc/bexport.go

@@ -140,12 +140,11 @@ const debugFormat = false // default: false
 const forceObjFileStability = true
 
 // Current export format version. Increase with each format change.
-// 4: type name objects support type aliases, uses aliasTag
-// 3: Go1.8 encoding (same as version 2, aliasTag defined but never used)
-// 2: removed unused bool in ODCL export (compiler only)
+// 3: added aliasTag and export of aliases
+// 2: removed unused bool in ODCL export
 // 1: header format change (more regular), export package for _ struct fields
 // 0: Go1.7 encoding
-const exportVersion = 4
+const exportVersion = 3
 
 // exportInlined enables the export of inlined function bodies and related
 // dependencies. The compiler should work w/o any loss of functionality with
@@ -352,8 +351,8 @@ func export(out *bufio.Writer, trace bool) int {
 			p.tracef("\n")
 		}
 
-		if sym.isAlias() {
-			Fatalf("exporter: unexpected type alias %v in inlined function body", sym)
+		if sym.Flags&SymAlias != 0 {
+			Fatalf("exporter: unexpected alias %v in inlined function body", sym)
 		}
 
 		p.obj(sym)
@@ -447,6 +446,30 @@ func unidealType(typ *Type, val Val) *Type {
 }
 
 func (p *exporter) obj(sym *Sym) {
+	if sym.Flags&SymAlias != 0 {
+		p.tag(aliasTag)
+		p.pos(nil) // TODO(gri) fix position information
+		// Aliases can only be exported from the package that
+		// declares them (aliases to aliases are resolved to the
+		// original object, and so are uses of aliases in inlined
+		// exported function bodies). Thus, we only need the alias
+		// name without package qualification.
+		if sym.Pkg != localpkg {
+			Fatalf("exporter: export of non-local alias: %v", sym)
+		}
+		p.string(sym.Name)
+		orig := sym.Def.Sym
+		if orig.Flags&SymAlias != 0 {
+			Fatalf("exporter: original object %v marked as alias", sym)
+		}
+		p.qualifiedName(orig)
+		return
+	}
+
+	if sym != sym.Def.Sym {
+		Fatalf("exporter: exported object %v is not original %v", sym, sym.Def.Sym)
+	}
+
 	// Exported objects may be from different packages because they
 	// may be re-exported via an exported alias or as dependencies in
 	// exported inlined function bodies. Thus, exported object names
@@ -486,13 +509,7 @@ func (p *exporter) obj(sym *Sym) {
 			Fatalf("exporter: export of incomplete type %v", sym)
 		}
 
-		if sym.isAlias() {
-			p.tag(aliasTag)
-			p.pos(n)
-			p.qualifiedName(sym)
-		} else {
-			p.tag(typeTag)
-		}
+		p.tag(typeTag)
 		p.typ(t)
 
 	case ONAME:
@@ -851,29 +868,19 @@ func (p *exporter) methodList(t *Type) {
 
 func (p *exporter) method(m *Field) {
 	p.pos(m.Nname)
-	p.methodName(m.Sym)
+	p.fieldName(m)
 	p.paramList(m.Type.Params(), false)
 	p.paramList(m.Type.Results(), false)
 }
 
+// fieldName is like qualifiedName but it doesn't record the package for exported names.
 func (p *exporter) fieldName(t *Field) {
 	name := t.Sym.Name
 	if t.Embedded != 0 {
-		// anonymous field - we distinguish between 3 cases:
-		// 1) field name matches base type name and is exported
-		// 2) field name matches base type name and is not exported
-		// 3) field name doesn't match base type name (alias name)
-		bname := basetypeName(t.Type)
-		if name == bname {
-			if exportname(name) {
-				name = "" // 1) we don't need to know the field name or package
-			} else {
-				name = "?" // 2) use unexported name "?" to force package export
-			}
-		} else {
-			// 3) indicate alias and export name as is
-			// (this requires an extra "@" but this is a rare case)
-			p.string("@")
+		name = "" // anonymous field
+		if bname := basetypeName(t.Type); bname != "" && !exportname(bname) {
+			// anonymous field with unexported base type name
+			name = "?" // unexported name to force export of package
 		}
 	}
 	p.string(name)
@@ -882,23 +889,16 @@ func (p *exporter) fieldName(t *Field) {
 	}
 }
 
-// methodName is like qualifiedName but it doesn't record the package for exported names.
-func (p *exporter) methodName(sym *Sym) {
-	p.string(sym.Name)
-	if !exportname(sym.Name) {
-		p.pkg(sym.Pkg)
-	}
-}
-
 func basetypeName(t *Type) string {
 	s := t.Sym
 	if s == nil && t.IsPtr() {
 		s = t.Elem().Sym // deref
 	}
+	// s should exist, but be conservative
 	if s != nil {
 		return s.Name
 	}
-	return "" // unnamed type
+	return ""
 }
 
 func (p *exporter) paramList(params *Type, numbered bool) {
@@ -1797,7 +1797,7 @@ const (
 	nilTag
 	unknownTag // not used by gc (only appears in packages with errors)
 
-	// Type aliases
+	// Aliases
 	aliasTag
 )
 
@@ -1835,7 +1835,7 @@ var tagString = [...]string{
 	-nilTag:      "nil",
 	-unknownTag:  "unknown",
 
-	// Type aliases
+	// Aliases
 	-aliasTag: "alias",
 }
 
@@ -1889,7 +1889,7 @@ func predeclared() []*Type {
 			Types[TCOMPLEX128],
 			Types[TSTRING],
 
-			// basic type aliases
+			// aliases
 			bytetype,
 			runetype,
 

src/cmd/compile/internal/gc/bimport.go

@@ -86,10 +86,10 @@ func Import(in *bufio.Reader) {
 
 	// read version specific flags - extend as necessary
 	switch p.version {
-	// case 5:
+	// case 4:
 	// 	...
 	//	fallthrough
-	case 4, 3, 2, 1:
+	case 3, 2, 1:
 		p.debugFormat = p.rawStringln(p.rawByte()) == "debug"
 		p.trackAllTypes = p.bool()
 		p.posInfoFormat = p.bool()
@@ -317,12 +317,6 @@ func (p *importer) obj(tag int) {
 		val := p.value(typ)
 		importconst(sym, idealType(typ), nodlit(val))
 
-	case aliasTag:
-		p.pos()
-		sym := p.qualifiedName()
-		typ := p.typ()
-		importalias(sym, typ)
-
 	case typeTag:
 		p.typ()
 
@@ -362,6 +356,17 @@ func (p *importer) obj(tag int) {
 			}
 		}
 
+	case aliasTag:
+		p.pos()
+		alias := importpkg.Lookup(p.string())
+		orig := p.qualifiedName()
+
+		// Although the protocol allows the alias to precede the original,
+		// this never happens in files produced by gc.
+		alias.Flags |= SymAlias
+		alias.Def = orig.Def
+		importsym(alias, orig.Def.Op)
+
 	default:
 		formatErrorf("unexpected object (tag = %d)", tag)
 	}
@@ -468,7 +473,14 @@ func (p *importer) typ() *Type {
 			result := p.paramList()
 			nointerface := p.bool()
 
-			n := newfuncname(methodname(sym, recv[0].Type))
+			base := recv[0].Type
+			star := false
+			if base.IsPtr() {
+				base = base.Elem()
+				star = true
+			}
+
+			n := methodname0(sym, star, base.Sym)
 			n.Type = functypefield(recv[0], params, result)
 			checkwidth(n.Type)
 			addmethod(sym, n.Type, false, nointerface)
@@ -571,22 +583,19 @@ func (p *importer) fieldList() (fields []*Field) {
 
 func (p *importer) field() *Field {
 	p.pos()
-	sym, alias := p.fieldName()
+	sym := p.fieldName()
 	typ := p.typ()
 	note := p.string()
 
 	f := newField()
 	if sym.Name == "" {
-		// anonymous field: typ must be T or *T and T must be a type name
+		// anonymous field - typ must be T or *T and T must be a type name
 		s := typ.Sym
 		if s == nil && typ.IsPtr() {
 			s = typ.Elem().Sym // deref
 		}
 		sym = sym.Pkg.Lookup(s.Name)
 		f.Embedded = 1
-	} else if alias {
-		// anonymous field: we have an explicit name because it's a type alias
-		f.Embedded = 1
 	}
 
 	f.Sym = sym
@@ -609,7 +618,7 @@ func (p *importer) methodList() (methods []*Field) {
 
 func (p *importer) method() *Field {
 	p.pos()
-	sym := p.methodName()
+	sym := p.fieldName()
 	params := p.paramList()
 	result := p.paramList()
 
@@ -620,44 +629,18 @@ func (p *importer) method() *Field {
 	return f
 }
 
-func (p *importer) fieldName() (*Sym, bool) {
+func (p *importer) fieldName() *Sym {
 	name := p.string()
 	if p.version == 0 && name == "_" {
-		// version 0 didn't export a package for _ field names
-		// but used the builtin package instead
-		return builtinpkg.Lookup(name), false
-	}
-	pkg := localpkg
-	alias := false
-	switch name {
-	case "":
-		// 1) field name matches base type name and is exported: nothing to do
-	case "?":
-		// 2) field name matches base type name and is not exported: need package
-		name = ""
-		pkg = p.pkg()
-	case "@":
-		// 3) field name doesn't match base type name (alias name): need name and possibly package
-		name = p.string()
-		alias = true
-		fallthrough
-	default:
-		if !exportname(name) {
-			pkg = p.pkg()
-		}
-	}
-	return pkg.Lookup(name), alias
-}
-
-func (p *importer) methodName() *Sym {
-	name := p.string()
-	if p.version == 0 && name == "_" {
-		// version 0 didn't export a package for _ method names
+		// version 0 didn't export a package for _ fields
 		// but used the builtin package instead
 		return builtinpkg.Lookup(name)
 	}
 	pkg := localpkg
-	if !exportname(name) {
+	if name != "" && !exportname(name) {
+		if name == "?" {
+			name = ""
+		}
 		pkg = p.pkg()
 	}
 	return pkg.Lookup(name)

src/cmd/compile/internal/gc/dcl.go

@@ -519,6 +519,10 @@ func funchdr(n *Node) {
 		Fatalf("funchdr: dclcontext = %d", dclcontext)
 	}
 
+	if Ctxt.Flag_dynlink && importpkg == nil && n.Func.Nname != nil {
+		makefuncsym(n.Func.Nname.Sym)
+	}
+
 	dclcontext = PAUTO
 	funcstart(n)
 
@@ -691,20 +695,10 @@ func typedcl0(s *Sym) *Node {
 
 // node n, which was returned by typedcl0
 // is being declared to have uncompiled type t.
-// returns the ODCLTYPE node to use.
-func typedcl1(n *Node, t *Node, pragma Pragma, alias bool) *Node {
-	if pragma != 0 && alias {
-		yyerror("cannot specify directive with type alias")
-		pragma = 0
-	}
-
-	n.Local = true
-
-	p := n.Name.Param
-	p.Ntype = t
-	p.Pragma = pragma
-	p.Alias = alias
-
+// return the ODCLTYPE node to use.
+func typedcl1(n *Node, t *Node, local bool) *Node {
+	n.Name.Param.Ntype = t
+	n.Local = local
 	return nod(ODCLTYPE, n, nil)
 }
 
@@ -1159,19 +1153,19 @@ bad:
 	return nil
 }
 
-// methodname is a misnomer because this now returns a Sym, rather
-// than an ONAME.
-// TODO(mdempsky): Reconcile with methodsym.
-func methodname(s *Sym, recv *Type) *Sym {
+func methodname(n *Node, t *Node) *Node {
 	star := false
-	if recv.IsPtr() {
+	if t.Op == OIND {
 		star = true
-		recv = recv.Elem()
+		t = t.Left
 	}
 
-	tsym := recv.Sym
+	return methodname0(n.Sym, star, t.Sym)
+}
+
+func methodname0(s *Sym, star bool, tsym *Sym) *Node {
 	if tsym == nil || isblanksym(s) {
-		return s
+		return newfuncname(s)
 	}
 
 	var p string
@@ -1187,13 +1181,14 @@ func methodname(s *Sym, recv *Type) *Sym {
 		s = Pkglookup(p, tsym.Pkg)
 	}
 
-	return s
+	return newfuncname(s)
 }
 
 // Add a method, declared as a function.
 // - msym is the method symbol
 // - t is function type (with receiver)
 func addmethod(msym *Sym, t *Type, local, nointerface bool) {
+	// get field sym
 	if msym == nil {
 		Fatalf("no method symbol")
 	}
@@ -1314,7 +1309,7 @@ func funcsym(s *Sym) *Sym {
 	s1 := Pkglookup(s.Name+"·f", s.Pkg)
 	if !Ctxt.Flag_dynlink && s1.Def == nil {
 		s1.Def = newfuncname(s1)
-		s1.Def.Func.Shortname = s
+		s1.Def.Func.Shortname = newname(s)
 		funcsyms = append(funcsyms, s1.Def)
 	}
 	s.Fsym = s1
@@ -1331,11 +1326,8 @@ func makefuncsym(s *Sym) {
 		return
 	}
 	s1 := funcsym(s)
-	if s1.Def != nil {
-		return
-	}
 	s1.Def = newfuncname(s1)
-	s1.Def.Func.Shortname = s
+	s1.Def.Func.Shortname = newname(s)
 	funcsyms = append(funcsyms, s1.Def)
 }
 

src/cmd/compile/internal/gc/export.go

@@ -45,8 +45,8 @@ func exportsym(n *Node) {
 		fmt.Printf("export symbol %v\n", n.Sym)
 	}
 
-	// Ensure original types are on exportlist before type aliases.
-	if n.Sym.isAlias() {
+	// Ensure original object is on exportlist before aliases.
+	if n.Sym.Flags&SymAlias != 0 {
 		exportlist = append(exportlist, n.Sym.Def)
 	}
 
@@ -83,7 +83,7 @@ func autoexport(n *Node, ctxt Class) {
 	if (ctxt != PEXTERN && ctxt != PFUNC) || dclcontext != PEXTERN {
 		return
 	}
-	if n.Type != nil && n.Type.IsKind(TFUNC) && n.Type.Recv() != nil { // method
+	if n.Name.Param != nil && n.Name.Param.Ntype != nil && n.Name.Param.Ntype.Op == OTFUNC && n.Name.Param.Ntype.Left != nil { // method
 		return
 	}
 
@@ -348,27 +348,6 @@ func importvar(s *Sym, t *Type) {
 	}
 }
 
-// importalias declares symbol s as an imported type alias with type t.
-func importalias(s *Sym, t *Type) {
-	importsym(s, OTYPE)
-	if s.Def != nil && s.Def.Op == OTYPE {
-		if eqtype(t, s.Def.Type) {
-			return
-		}
-		yyerror("inconsistent definition for type alias %v during import\n\t%v (in %q)\n\t%v (in %q)", s, s.Def.Type, s.Importdef.Path, t, importpkg.Path)
-	}
-
-	n := newname(s)
-	n.Op = OTYPE
-	s.Importdef = importpkg
-	n.Type = t
-	declare(n, PEXTERN)
-
-	if Debug['E'] != 0 {
-		fmt.Printf("import type %v = %L\n", s, t)
-	}
-}
-
 func dumpasmhdr() {
 	b, err := bio.Create(asmhdr)
 	if err != nil {

src/cmd/compile/internal/gc/fmt.go

@@ -1077,7 +1077,6 @@ var opprec = []int{
 	OSEND:         3,
 	OANDAND:       2,
 	OOROR:         1,
-
 	// Statements handled by stmtfmt
 	OAS:         -1,
 	OAS2:        -1,
@@ -1105,8 +1104,7 @@ var opprec = []int{
 	OSWITCH:     -1,
 	OXCASE:      -1,
 	OXFALL:      -1,
-
-	OEND: 0,
+	OEND:        0,
 }
 
 func (n *Node) exprfmt(s fmt.State, prec int) {

src/cmd/compile/internal/gc/go.go

@@ -63,12 +63,9 @@ const (
 	SymSiggen
 	SymAsm
 	SymAlgGen
+	SymAlias // alias, original is Sym.Def.Sym
 )
 
-func (sym *Sym) isAlias() bool {
-	return sym.Def != nil && sym.Def.Sym != sym
-}
-
 // The Class of a variable/function describes the "storage class"
 // of a variable or function. During parsing, storage classes are
 // called declaration contexts.
@@ -90,7 +87,7 @@ const (
 // of the compilers arrays.
 //
 // typedef	struct
-// {				// must not move anything
+// {					// must not move anything
 // 	uchar	array[8];	// pointer to data
 // 	uchar	nel[4];		// number of elements
 // 	uchar	cap[4];		// allocated number of elements
@@ -107,7 +104,7 @@ var sizeof_Array int // runtime sizeof(Array)
 // of the compilers strings.
 //
 // typedef	struct
-// {				// must not move anything
+// {					// must not move anything
 // 	uchar	array[8];	// pointer to data
 // 	uchar	nel[4];		// number of elements
 // } String;
@@ -251,6 +248,7 @@ var nblank *Node
 var typecheckok bool
 
 var compiling_runtime bool
+var compiling_std bool
 
 var compiling_wrappers int
 

src/cmd/compile/internal/gc/main.go

@@ -154,6 +154,7 @@ func Main() {
 	}
 
 	flag.BoolVar(&compiling_runtime, "+", false, "compiling runtime")
+	flag.BoolVar(&compiling_std, "std", false, "compiling standard library")
 	obj.Flagcount("%", "debug non-static initializers", &Debug['%'])
 	obj.Flagcount("B", "disable bounds checking", &Debug['B'])
 	flag.StringVar(&localimport, "D", "", "set relative `path` for local imports")
@@ -340,16 +341,13 @@ func Main() {
 	// Phase 1: const, type, and names and types of funcs.
 	//   This will gather all the information about types
 	//   and methods but doesn't depend on any of it.
-	//   We also defer type alias declarations until phase 2
-	//   to avoid cycles like #18640.
 	defercheckwidth()
 
 	// Don't use range--typecheck can add closures to xtop.
 	timings.Start("fe", "typecheck", "top1")
 	for i := 0; i < len(xtop); i++ {
-		n := xtop[i]
-		if op := n.Op; op != ODCL && op != OAS && op != OAS2 && (op != ODCLTYPE || !n.Left.Name.Param.Alias) {
-			xtop[i] = typecheck(n, Etop)
+		if xtop[i].Op != ODCL && xtop[i].Op != OAS && xtop[i].Op != OAS2 {
+			xtop[i] = typecheck(xtop[i], Etop)
 		}
 	}
 
@@ -359,9 +357,8 @@ func Main() {
 	// Don't use range--typecheck can add closures to xtop.
 	timings.Start("fe", "typecheck", "top2")
 	for i := 0; i < len(xtop); i++ {
-		n := xtop[i]
-		if op := n.Op; op == ODCL || op == OAS || op == OAS2 || op == ODCLTYPE && n.Left.Name.Param.Alias {
-			xtop[i] = typecheck(n, Etop)
+		if xtop[i].Op == ODCL || xtop[i].Op == OAS || xtop[i].Op == OAS2 {
+			xtop[i] = typecheck(xtop[i], Etop)
 		}
 	}
 	resumecheckwidth()
@@ -371,9 +368,8 @@ func Main() {
 	timings.Start("fe", "typecheck", "func")
 	var fcount int64
 	for i := 0; i < len(xtop); i++ {
-		n := xtop[i]
-		if op := n.Op; op == ODCLFUNC || op == OCLOSURE {
-			Curfn = n
+		if xtop[i].Op == ODCLFUNC || xtop[i].Op == OCLOSURE {
+			Curfn = xtop[i]
 			decldepth = 1
 			saveerrors()
 			typecheckslice(Curfn.Nbody.Slice(), Etop)
@@ -465,9 +461,8 @@ func Main() {
 	timings.Start("be", "compilefuncs")
 	fcount = 0
 	for i := 0; i < len(xtop); i++ {
-		n := xtop[i]
-		if n.Op == ODCLFUNC {
-			funccompile(n)
+		if xtop[i].Op == ODCLFUNC {
+			funccompile(xtop[i])
 			fcount++
 		}
 	}
@@ -930,7 +925,7 @@ func mkpackage(pkgname string) {
 				continue
 			}
 
-			if s.isAlias() {
+			if s.Def.Sym != s && s.Flags&SymAlias == 0 {
 				// throw away top-level name left over
 				// from previous import . "x"
 				if s.Def.Name != nil && s.Def.Name.Pack != nil && !s.Def.Name.Pack.Used && nsyntaxerrors == 0 {

src/cmd/compile/internal/gc/noder.go

@@ -7,6 +7,7 @@ package gc
 import (
 	"fmt"
 	"os"
+	"path/filepath"
 	"strconv"
 	"strings"
 	"unicode/utf8"
@@ -154,7 +155,11 @@ func (p *noder) importDecl(imp *syntax.ImportDecl) {
 
 func (p *noder) varDecl(decl *syntax.VarDecl) []*Node {
 	names := p.declNames(decl.NameList)
-	typ := p.typeExprOrNil(decl.Type)
+
+	var typ *Node
+	if decl.Type != nil {
+		typ = p.typeExpr(decl.Type)
+	}
 
 	var exprs []*Node
 	if decl.Values != nil {
@@ -167,7 +172,11 @@ func (p *noder) varDecl(decl *syntax.VarDecl) []*Node {
 
 func (p *noder) constDecl(decl *syntax.ConstDecl) []*Node {
 	names := p.declNames(decl.NameList)
-	typ := p.typeExprOrNil(decl.Type)
+
+	var typ *Node
+	if decl.Type != nil {
+		typ = p.typeExpr(decl.Type)
+	}
 
 	var exprs []*Node
 	if decl.Values != nil {
@@ -179,11 +188,14 @@ func (p *noder) constDecl(decl *syntax.ConstDecl) []*Node {
 
 func (p *noder) typeDecl(decl *syntax.TypeDecl) *Node {
 	name := typedcl0(p.name(decl.Name))
+	name.Name.Param.Pragma = Pragma(decl.Pragma)
 
-	// decl.Type may be nil but in that case we got a syntax error during parsing
-	typ := p.typeExprOrNil(decl.Type)
+	var typ *Node
+	if decl.Type != nil {
+		typ = p.typeExpr(decl.Type)
+	}
 
-	return typedcl1(name, typ, Pragma(decl.Pragma), decl.Alias)
+	return typedcl1(name, typ, true)
 }
 
 func (p *noder) declNames(names []*syntax.Name) []*Node {
@@ -248,19 +260,19 @@ func (p *noder) funcHeader(fun *syntax.FuncDecl) *Node {
 				yyerror("func main must have no arguments and no return values")
 			}
 		}
+
+		f.Func.Nname = newfuncname(name)
 	} else {
-		f.Func.Shortname = name
-		name = nblank.Sym // filled in by typecheckfunc
+		// Receiver MethodName Signature
+
+		f.Func.Shortname = newfuncname(name)
+		f.Func.Nname = methodname(f.Func.Shortname, t.Left.Right)
 	}
 
-	f.Func.Nname = newfuncname(name)
 	f.Func.Nname.Name.Defn = f
 	f.Func.Nname.Name.Param.Ntype = t // TODO: check if nname already has an ntype
 
-	if fun.Recv == nil {
-		declare(f.Func.Nname, PFUNC)
-	}
-
+	declare(f.Func.Nname, PFUNC)
 	funchdr(f)
 	return f
 }
@@ -456,13 +468,6 @@ func (p *noder) typeExpr(typ syntax.Expr) *Node {
 	return p.expr(typ)
 }
 
-func (p *noder) typeExprOrNil(typ syntax.Expr) *Node {
-	if typ != nil {
-		return p.expr(typ)
-	}
-	return nil
-}
-
 func (p *noder) chanDir(dir syntax.ChanDir) ChanDir {
 	switch dir {
 	case 0:
@@ -1053,6 +1058,11 @@ func (p *noder) pragma(pos, line int, text string) syntax.Pragma {
 
 	case strings.HasPrefix(text, "go:cgo_"):
 		lineno = p.baseline + int32(line) - 1 // pragcgo may call yyerror
+		// For security, we disallow //go:cgo_* directives outside cgo-generated files.
+		// Exception: they are allowed in the standard library, for runtime and syscall.
+		if !isCgoGeneratedFile() && !compiling_std {
+			p.error(syntax.Error{Pos: pos, Line: line, Msg: fmt.Sprintf("//%s only allowed in cgo-generated code", text)})
+		}
 		pragcgobuf += pragcgo(text)
 		fallthrough // because of //go:cgo_unsafe_args
 	default:
@@ -1067,6 +1077,20 @@ func (p *noder) pragma(pos, line int, text string) syntax.Pragma {
 	return 0
 }
 
+// isCgoGeneratedFile reports whether lineno is in a file
+// generated by cgo, which is to say a file with name
+// beginning with "_cgo_". Such files are allowed to
+// contain cgo directives, and for security reasons
+// (primarily misuse of linker flags), other files are not.
+// See golang.org/issue/23672.
+func isCgoGeneratedFile() bool {
+	stk := Ctxt.LineHist.At(int(lineno))
+	if stk == nil {
+		return false
+	}
+	return strings.HasPrefix(filepath.Base(filepath.Clean(stk.File)), "_cgo_")
+}
+
 func mkname(sym *Sym) *Node {
 	n := oldname(sym)
 	if n.Name != nil && n.Name.Pack != nil {

src/cmd/compile/internal/gc/obj.go

@@ -213,7 +213,7 @@ func dumpglobls() {
 	}
 
 	for _, n := range funcsyms {
-		dsymptr(n.Sym, 0, n.Sym.Def.Func.Shortname, 0)
+		dsymptr(n.Sym, 0, n.Sym.Def.Func.Shortname.Sym, 0)
 		ggloblsym(n.Sym, int32(Widthptr), obj.DUPOK|obj.RODATA)
 	}
 

src/cmd/compile/internal/gc/reflect.go

@@ -511,7 +511,7 @@ func isExportedField(ft *Field) (bool, *Pkg) {
 // dnameField dumps a reflect.name for a struct field.
 func dnameField(s *Sym, ot int, spkg *Pkg, ft *Field) int {
 	var name string
-	if ft.Sym != nil {
+	if ft.Sym != nil && ft.Embedded == 0 {
 		name = ft.Sym.Name
 	}
 	isExported, fpkg := isExportedField(ft)
@@ -1345,14 +1345,7 @@ ok:
 			// ../../../../runtime/type.go:/structField
 			ot = dnameField(s, ot, pkg, f)
 			ot = dsymptr(s, ot, dtypesym(f.Type), 0)
-			offsetAnon := uint64(f.Offset) << 1
-			if offsetAnon>>1 != uint64(f.Offset) {
-				Fatalf("%v: bad field offset for %s", t, f.Sym.Name)
-			}
-			if f.Embedded != 0 {
-				offsetAnon |= 1
-			}
-			ot = duintptr(s, ot, offsetAnon)
+			ot = duintptr(s, ot, uint64(f.Offset))
 		}
 	}
 

src/cmd/compile/internal/gc/syntax.go

@@ -27,7 +27,7 @@ type Node struct {
 	// func
 	Func *Func
 
-	// ONAME, OTYPE, OPACK, OLABEL, some OLITERAL
+	// ONAME
 	Name *Name
 
 	Sym *Sym        // various
@@ -59,8 +59,8 @@ type Node struct {
 	Noescape  bool  // func arguments do not escape; TODO(rsc): move Noescape to Func struct (see CL 7360)
 	Walkdef   uint8 // tracks state during typecheckdef; 2 == loop detected
 	Typecheck uint8 // tracks state during typechecking; 2 == loop detected
-	Local     bool  // type created in this file (see also Type.Local); TODO(gri): move this into flags
-	IsStatic  bool  // whether this Node will be converted to purely static data
+	Local     bool
+	IsStatic  bool // whether this Node will be converted to purely static data
 	Initorder uint8
 	Used      bool // for variable/label declared and not used error
 	Isddd     bool // is the argument variadic
@@ -180,14 +180,14 @@ func (n *Node) SetIota(x int64) {
 	n.Xoffset = x
 }
 
-// Name holds Node fields used only by named nodes (ONAME, OTYPE, OPACK, OLABEL, some OLITERAL).
+// Name holds Node fields used only by named nodes (ONAME, OPACK, OLABEL, some OLITERAL).
 type Name struct {
 	Pack      *Node  // real package for import . names
 	Pkg       *Pkg   // pkg for OPACK nodes
 	Heapaddr  *Node  // temp holding heap address of param (could move to Param?)
 	Defn      *Node  // initializing assignment
 	Curfn     *Node  // function for local variables
-	Param     *Param // additional fields for ONAME, OTYPE
+	Param     *Param // additional fields for ONAME
 	Decldepth int32  // declaration loop depth, increased for every loop or label
 	Vargen    int32  // unique name for ONAME within a function.  Function outputs are numbered starting at one.
 	Funcdepth int32
@@ -280,16 +280,15 @@ type Param struct {
 	Innermost *Node
 	Outer     *Node
 
-	// OTYPE
+	// OTYPE pragmas
 	//
 	// TODO: Should Func pragmas also be stored on the Name?
 	Pragma Pragma
-	Alias  bool // node is alias for Ntype (only used when type-checking ODCLTYPE)
 }
 
 // Func holds Node fields used only with function-like nodes.
 type Func struct {
-	Shortname  *Sym
+	Shortname  *Node
 	Enter      Nodes // for example, allocate and initialize memory for escaping parameters
 	Exit       Nodes
 	Cvars      Nodes   // closure params
@@ -383,7 +382,7 @@ const (
 	ODCLFUNC  // func f() or func (r) f()
 	ODCLFIELD // struct field, interface field, or func/method argument/return value.
 	ODCLCONST // const pi = 3.14
-	ODCLTYPE  // type Int int or type Int = int
+	ODCLTYPE  // type Int int
 
 	ODELETE    // delete(Left, Right)
 	ODOT       // Left.Sym (Left is of struct type)

src/cmd/compile/internal/gc/testdata/loadstore.go

@@ -102,12 +102,120 @@ func testDeadStorePanic() {
 	}
 }
 
+//go:noinline
+func loadHitStore8(x int8, p *int8) int32 {
+	x *= x           // try to trash high bits (arch-dependent)
+	*p = x           // store
+	return int32(*p) // load and cast
+}
+
+//go:noinline
+func loadHitStoreU8(x uint8, p *uint8) uint32 {
+	x *= x            // try to trash high bits (arch-dependent)
+	*p = x            // store
+	return uint32(*p) // load and cast
+}
+
+//go:noinline
+func loadHitStore16(x int16, p *int16) int32 {
+	x *= x           // try to trash high bits (arch-dependent)
+	*p = x           // store
+	return int32(*p) // load and cast
+}
+
+//go:noinline
+func loadHitStoreU16(x uint16, p *uint16) uint32 {
+	x *= x            // try to trash high bits (arch-dependent)
+	*p = x            // store
+	return uint32(*p) // load and cast
+}
+
+//go:noinline
+func loadHitStore32(x int32, p *int32) int64 {
+	x *= x           // try to trash high bits (arch-dependent)
+	*p = x           // store
+	return int64(*p) // load and cast
+}
+
+//go:noinline
+func loadHitStoreU32(x uint32, p *uint32) uint64 {
+	x *= x            // try to trash high bits (arch-dependent)
+	*p = x            // store
+	return uint64(*p) // load and cast
+}
+
+func testLoadHitStore() {
+	// Test that sign/zero extensions are kept when a load-hit-store
+	// is replaced by a register-register move.
+	{
+		var in int8 = (1 << 6) + 1
+		var p int8
+		got := loadHitStore8(in, &p)
+		want := int32(in * in)
+		if got != want {
+			fmt.Println("testLoadHitStore (int8) failed. want =", want, ", got =", got)
+			failed = true
+		}
+	}
+	{
+		var in uint8 = (1 << 6) + 1
+		var p uint8
+		got := loadHitStoreU8(in, &p)
+		want := uint32(in * in)
+		if got != want {
+			fmt.Println("testLoadHitStore (uint8) failed. want =", want, ", got =", got)
+			failed = true
+		}
+	}
+	{
+		var in int16 = (1 << 10) + 1
+		var p int16
+		got := loadHitStore16(in, &p)
+		want := int32(in * in)
+		if got != want {
+			fmt.Println("testLoadHitStore (int16) failed. want =", want, ", got =", got)
+			failed = true
+		}
+	}
+	{
+		var in uint16 = (1 << 10) + 1
+		var p uint16
+		got := loadHitStoreU16(in, &p)
+		want := uint32(in * in)
+		if got != want {
+			fmt.Println("testLoadHitStore (uint16) failed. want =", want, ", got =", got)
+			failed = true
+		}
+	}
+	{
+		var in int32 = (1 << 30) + 1
+		var p int32
+		got := loadHitStore32(in, &p)
+		want := int64(in * in)
+		if got != want {
+			fmt.Println("testLoadHitStore (int32) failed. want =", want, ", got =", got)
+			failed = true
+		}
+	}
+	{
+		var in uint32 = (1 << 30) + 1
+		var p uint32
+		got := loadHitStoreU32(in, &p)
+		want := uint64(in * in)
+		if got != want {
+			fmt.Println("testLoadHitStore (uint32) failed. want =", want, ", got =", got)
+			failed = true
+		}
+	}
+}
+
 func main() {
 
 	testLoadStoreOrder()
 	testStoreSize()
 	testExtStore()
 	testDeadStorePanic()
+	testLoadHitStore()
 
 	if failed {
 		panic("failed")

src/cmd/compile/internal/gc/typecheck.go

@@ -96,16 +96,16 @@ func typekind(t *Type) string {
 	return fmt.Sprintf("etype=%d", et)
 }
 
-// sprint_depchain prints a dependency chain of nodes into trace.
+// sprint_depchain prints a dependency chain of nodes into fmt.
 // It is used by typecheck in the case of OLITERAL nodes
 // to print constant definition loops.
-func sprint_depchain(trace *string, stack []*Node, cur *Node, first *Node) {
+func sprint_depchain(fmt_ *string, stack []*Node, cur *Node, first *Node) {
 	for i := len(stack) - 1; i >= 0; i-- {
 		if n := stack[i]; n.Op == cur.Op {
 			if n != first {
-				sprint_depchain(trace, stack[:i], n, first)
+				sprint_depchain(fmt_, stack[:i], n, first)
 			}
-			*trace += fmt.Sprintf("\n\t%v: %v uses %v", n.Line(), n, cur)
+			*fmt_ += fmt.Sprintf("\n\t%v: %v uses %v", n.Line(), n, cur)
 			return
 		}
 	}
@@ -152,6 +152,7 @@ func typecheck(n *Node, top int) *Node {
 	if n.Typecheck == 2 {
 		// Typechecking loop. Trying printing a meaningful message,
 		// otherwise a stack trace of typechecking.
+		var fmt_ string
 		switch n.Op {
 		// We can already diagnose variables used as types.
 		case ONAME:
@@ -159,30 +160,22 @@ func typecheck(n *Node, top int) *Node {
 				yyerror("%v is not a type", n)
 			}
 
-		case OTYPE:
-			if top&Etype == Etype {
-				var trace string
-				sprint_depchain(&trace, typecheck_tcstack, n, n)
-				yyerrorl(n.Lineno, "invalid recursive type alias %v%s", n, trace)
-			}
-
 		case OLITERAL:
 			if top&(Erv|Etype) == Etype {
 				yyerror("%v is not a type", n)
 				break
 			}
-			var trace string
-			sprint_depchain(&trace, typecheck_tcstack, n, n)
-			yyerrorl(n.Lineno, "constant definition loop%s", trace)
+			sprint_depchain(&fmt_, typecheck_tcstack, n, n)
+			yyerrorl(n.Lineno, "constant definition loop%s", fmt_)
 		}
 
 		if nsavederrors+nerrors == 0 {
-			var trace string
+			fmt_ = ""
 			for i := len(typecheck_tcstack) - 1; i >= 0; i-- {
 				x := typecheck_tcstack[i]
-				trace += fmt.Sprintf("\n\t%v %v", x.Line(), x)
+				fmt_ += fmt.Sprintf("\n\t%v %v", x.Line(), x)
 			}
-			yyerror("typechecking loop involving %v%s", n, trace)
+			yyerror("typechecking loop involving %v%s", n, fmt_)
 		}
 
 		lineno = lno
@@ -3435,14 +3428,7 @@ func typecheckfunc(n *Node) {
 	t.SetNname(n.Func.Nname)
 	rcvr := t.Recv()
 	if rcvr != nil && n.Func.Shortname != nil {
-		n.Func.Nname.Sym = methodname(n.Func.Shortname, rcvr.Type)
-		declare(n.Func.Nname, PFUNC)
-
-		addmethod(n.Func.Shortname, t, true, n.Func.Pragma&Nointerface != 0)
-	}
-
-	if Ctxt.Flag_dynlink && importpkg == nil && n.Func.Nname != nil {
-		makefuncsym(n.Func.Nname.Sym)
+		addmethod(n.Func.Shortname.Sym, t, true, n.Func.Pragma&Nointerface != 0)
 	}
 }
 
@@ -3591,6 +3577,8 @@ func typecheckdeftype(n *Node) {
 
 	// copy new type and clear fields
 	// that don't come along.
+	// anything zeroed here must be zeroed in
+	// typedcl2 too.
 	copytype(n, t)
 
 ret:
@@ -3769,29 +3757,12 @@ func typecheckdef(n *Node) *Node {
 		n.Name.Defn = typecheck(n.Name.Defn, Etop) // fills in n->type
 
 	case OTYPE:
-		if p := n.Name.Param; p.Alias {
-			// Type alias declaration: Simply use the rhs type - no need
-			// to create a new type.
-			// If we have a syntax error, p.Ntype may be nil.
-			if p.Ntype != nil {
-				p.Ntype = typecheck(p.Ntype, Etype)
-				n.Type = p.Ntype.Type
-				if n.Type == nil {
-					n.Diag = true
-					goto ret
-				}
-				n.Sym.Def = p.Ntype
-			}
-			break
-		}
-
-		// regular type declaration
 		if Curfn != nil {
 			defercheckwidth()
 		}
 		n.Walkdef = 1
 		n.Type = typ(TFORW)
-		n.Type.Sym = n.Sym // TODO(gri) this also happens in typecheckdeftype(n) - where should it happen?
+		n.Type.Sym = n.Sym
 		nerrors0 := nerrors
 		typecheckdeftype(n)
 		if n.Type.Etype == TFORW && nerrors > nerrors0 {
@@ -3799,6 +3770,7 @@ func typecheckdef(n *Node) *Node {
 			// but it was reported. Silence future errors.
 			n.Type.Broke = true
 		}
+
 		if Curfn != nil {
 			resumecheckwidth()
 		}

src/cmd/compile/internal/gc/universe.go

@@ -398,14 +398,6 @@ func lexinit1() {
 	// errortype.Orig = makeErrorInterface()
 	s.Def = typenod(errortype)
 
-	// We create separate byte and rune types for better error messages
-	// rather than just creating type alias *Sym's for the uint8 and
-	// int32 types. Hence, (bytetype|runtype).Sym.isAlias() is false.
-	// TODO(gri) Should we get rid of this special case (at the cost
-	// of less informative error messages involving bytes and runes)?
-	// (Alternatively, we could introduce an OTALIAS node representing
-	// type aliases, albeit at the cost of having to deal with it everywhere).
-
 	// byte alias
 	s = Pkglookup("byte", builtinpkg)
 	bytetype = typ(TUINT8)

src/cmd/compile/internal/ssa/gen/386.rules

@@ -620,10 +620,12 @@
 (MOVWLZX x:(MOVWloadidx1 [off] {sym} ptr idx mem)) && x.Uses == 1 && clobber(x) -> @x.Block (MOVWloadidx1 <v.Type> [off] {sym} ptr idx mem)
 (MOVWLZX x:(MOVWloadidx2 [off] {sym} ptr idx mem)) && x.Uses == 1 && clobber(x) -> @x.Block (MOVWloadidx2 <v.Type> [off] {sym} ptr idx mem)
 
-// replace load from same location as preceding store with copy
-(MOVBload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
-(MOVWload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
+// replace load from same location as preceding store with zero/sign extension (or copy in case of full width)
+(MOVBload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVBLZX x)
+(MOVWload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVWLZX x)
 (MOVLload [off] {sym} ptr (MOVLstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
+(MOVBLSXload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVBLSX x)
+(MOVWLSXload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVWLSX x)
 
 // Fold extensions and ANDs together.
 (MOVBLZX (ANDLconst [c] x)) -> (ANDLconst [c & 0xff] x)

src/cmd/compile/internal/ssa/gen/AMD64.rules

@@ -762,11 +762,14 @@
 (MOVLQZX x:(MOVLloadidx1 [off] {sym} ptr idx mem)) && x.Uses == 1 && clobber(x) -> @x.Block (MOVLloadidx1 <v.Type> [off] {sym} ptr idx mem)
 (MOVLQZX x:(MOVLloadidx4 [off] {sym} ptr idx mem)) && x.Uses == 1 && clobber(x) -> @x.Block (MOVLloadidx4 <v.Type> [off] {sym} ptr idx mem)
 
-// replace load from same location as preceding store with copy
-(MOVBload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
-(MOVWload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
-(MOVLload [off] {sym} ptr (MOVLstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
+// replace load from same location as preceding store with zero/sign extension (or copy in case of full width)
+(MOVBload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVBQZX x)
+(MOVWload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVWQZX x)
+(MOVLload [off] {sym} ptr (MOVLstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVLQZX x)
 (MOVQload [off] {sym} ptr (MOVQstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
+(MOVBQSXload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVBQSX x)
+(MOVWQSXload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVWQSX x)
+(MOVLQSXload [off] {sym} ptr (MOVLstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVLQSX x)
 
 // Fold extensions and ANDs together.
 (MOVBQZX (ANDLconst [c] x)) -> (ANDLconst [c & 0xff] x)

src/cmd/compile/internal/ssa/gen/ARM.rules

@@ -467,12 +467,13 @@
 (MOVDstore [off1] {sym1} (MOVWaddr [off2] {sym2} ptr) val mem) && canMergeSym(sym1,sym2) ->
 	(MOVDstore [off1+off2] {mergeSym(sym1,sym2)} ptr val mem)
 
-// replace load from same location as preceding store with copy
-(MOVBload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && isSigned(x.Type) -> x
-(MOVBUload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && !isSigned(x.Type) -> x
-(MOVHload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && isSigned(x.Type) -> x
-(MOVHUload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && !isSigned(x.Type) -> x
+// replace load from same location as preceding store with zero/sign extension (or copy in case of full width)
+(MOVBload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVBreg x)
+(MOVBUload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVBUreg x)
+(MOVHload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVHreg x)
+(MOVHUload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVHUreg x)
 (MOVWload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
+
 (MOVFload [off] {sym} ptr (MOVFstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
 (MOVDload [off] {sym} ptr (MOVDstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
 

src/cmd/compile/internal/ssa/gen/ARM64.rules

@@ -679,14 +679,14 @@
 (MOVWstore [off] {sym} ptr (MOVDconst [0]) mem) -> (MOVWstorezero [off] {sym} ptr mem)
 (MOVDstore [off] {sym} ptr (MOVDconst [0]) mem) -> (MOVDstorezero [off] {sym} ptr mem)
 
-// replace load from same location as preceding store with copy
+// replace load from same location as preceding store with zero/sign extension (or copy in case of full width)
 // these seem to have bad interaction with other rules, resulting in slower code
-//(MOVBload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
-//(MOVBUload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
-//(MOVHload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
-//(MOVHUload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
-//(MOVWload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
-//(MOVWUload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
+//(MOVBload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVBreg x)
+//(MOVBUload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVBUreg x)
+//(MOVHload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVHreg x)
+//(MOVHUload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVHUreg x)
+//(MOVWload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVWreg x)
+//(MOVWUload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVWUreg x)
 //(MOVDload [off] {sym} ptr (MOVDstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
 //(FMOVSload [off] {sym} ptr (FMOVSstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
 //(FMOVDload [off] {sym} ptr (FMOVDstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x

src/cmd/compile/internal/ssa/gen/MIPS.rules

@@ -522,11 +522,11 @@
 (MOVWstorezero [off1] {sym1} (MOVWaddr [off2] {sym2} ptr) mem) && canMergeSym(sym1,sym2) ->
 	(MOVWstorezero [off1+off2] {mergeSym(sym1,sym2)} ptr mem)
 
-// replace load from same location as preceding store with copy
-(MOVBload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && isSigned(x.Type) -> x
-(MOVBUload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && !isSigned(x.Type) -> x
-(MOVHload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && isSigned(x.Type) -> x
-(MOVHUload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && !isSigned(x.Type) -> x
+// replace load from same location as preceding store with zero/sign extension (or copy in case of full width)
+(MOVBload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVBreg x)
+(MOVBUload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVBUreg x)
+(MOVHload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVHreg x)
+(MOVHUload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVHUreg x)
 (MOVWload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
 (MOVFload [off] {sym} ptr (MOVFstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x
 (MOVDload [off] {sym} ptr (MOVDstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> x

src/cmd/compile/internal/ssa/gen/S390X.rules

@@ -656,9 +656,9 @@
 (MOVWZreg x:(MOVWZloadidx [off] {sym} ptr idx mem)) && x.Uses == 1 && clobber(x) -> @x.Block (MOVWZloadidx <v.Type> [off] {sym} ptr idx mem)
 
 // replace load from same location as preceding store with copy
-(MOVBZload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVDreg x)
-(MOVHZload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVDreg x)
-(MOVWZload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVDreg x)
+(MOVBZload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVBZreg x)
+(MOVHZload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVHZreg x)
+(MOVWZload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVWZreg x)
 (MOVDload [off] {sym} ptr (MOVDstore [off2] {sym2} ptr2 x _)) && sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) -> (MOVDreg x)
 
 // Don't extend before storing

src/cmd/compile/internal/ssa/rewrite386.go

@@ -2503,6 +2503,28 @@ func rewriteValue386_Op386MOVBLSX(v *Value, config *Config) bool {
 func rewriteValue386_Op386MOVBLSXload(v *Value, config *Config) bool {
 	b := v.Block
 	_ = b
+	// match: (MOVBLSXload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _))
+	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
+	// result: (MOVBLSX x)
+	for {
+		off := v.AuxInt
+		sym := v.Aux
+		ptr := v.Args[0]
+		v_1 := v.Args[1]
+		if v_1.Op != Op386MOVBstore {
+			break
+		}
+		off2 := v_1.AuxInt
+		sym2 := v_1.Aux
+		ptr2 := v_1.Args[0]
+		x := v_1.Args[1]
+		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
+			break
+		}
+		v.reset(Op386MOVBLSX)
+		v.AddArg(x)
+		return true
+	}
 	// match: (MOVBLSXload [off1] {sym1} (LEAL [off2] {sym2} base) mem)
 	// cond: is32Bit(off1+off2) && canMergeSym(sym1, sym2)   && (base.Op != OpSB || !config.ctxt.Flag_shared)
 	// result: (MOVBLSXload [off1+off2] {mergeSym(sym1,sym2)} base mem)
@@ -2606,7 +2628,7 @@ func rewriteValue386_Op386MOVBload(v *Value, config *Config) bool {
 	_ = b
 	// match: (MOVBload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _))
 	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
-	// result: x
+	// result: (MOVBLZX x)
 	for {
 		off := v.AuxInt
 		sym := v.Aux
@@ -2622,8 +2644,7 @@ func rewriteValue386_Op386MOVBload(v *Value, config *Config) bool {
 		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
 			break
 		}
-		v.reset(OpCopy)
-		v.Type = x.Type
+		v.reset(Op386MOVBLZX)
 		v.AddArg(x)
 		return true
 	}
@@ -5248,6 +5269,28 @@ func rewriteValue386_Op386MOVWLSX(v *Value, config *Config) bool {
 func rewriteValue386_Op386MOVWLSXload(v *Value, config *Config) bool {
 	b := v.Block
 	_ = b
+	// match: (MOVWLSXload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _))
+	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
+	// result: (MOVWLSX x)
+	for {
+		off := v.AuxInt
+		sym := v.Aux
+		ptr := v.Args[0]
+		v_1 := v.Args[1]
+		if v_1.Op != Op386MOVWstore {
+			break
+		}
+		off2 := v_1.AuxInt
+		sym2 := v_1.Aux
+		ptr2 := v_1.Args[0]
+		x := v_1.Args[1]
+		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
+			break
+		}
+		v.reset(Op386MOVWLSX)
+		v.AddArg(x)
+		return true
+	}
 	// match: (MOVWLSXload [off1] {sym1} (LEAL [off2] {sym2} base) mem)
 	// cond: is32Bit(off1+off2) && canMergeSym(sym1, sym2)   && (base.Op != OpSB || !config.ctxt.Flag_shared)
 	// result: (MOVWLSXload [off1+off2] {mergeSym(sym1,sym2)} base mem)
@@ -5378,7 +5421,7 @@ func rewriteValue386_Op386MOVWload(v *Value, config *Config) bool {
 	_ = b
 	// match: (MOVWload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _))
 	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
-	// result: x
+	// result: (MOVWLZX x)
 	for {
 		off := v.AuxInt
 		sym := v.Aux
@@ -5394,8 +5437,7 @@ func rewriteValue386_Op386MOVWload(v *Value, config *Config) bool {
 		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
 			break
 		}
-		v.reset(OpCopy)
-		v.Type = x.Type
+		v.reset(Op386MOVWLZX)
 		v.AddArg(x)
 		return true
 	}

src/cmd/compile/internal/ssa/rewriteAMD64.go

@@ -3361,6 +3361,28 @@ func rewriteValueAMD64_OpAMD64MOVBQSX(v *Value, config *Config) bool {
 func rewriteValueAMD64_OpAMD64MOVBQSXload(v *Value, config *Config) bool {
 	b := v.Block
 	_ = b
+	// match: (MOVBQSXload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _))
+	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
+	// result: (MOVBQSX x)
+	for {
+		off := v.AuxInt
+		sym := v.Aux
+		ptr := v.Args[0]
+		v_1 := v.Args[1]
+		if v_1.Op != OpAMD64MOVBstore {
+			break
+		}
+		off2 := v_1.AuxInt
+		sym2 := v_1.Aux
+		ptr2 := v_1.Args[0]
+		x := v_1.Args[1]
+		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
+			break
+		}
+		v.reset(OpAMD64MOVBQSX)
+		v.AddArg(x)
+		return true
+	}
 	// match: (MOVBQSXload [off1] {sym1} (LEAQ [off2] {sym2} base) mem)
 	// cond: is32Bit(off1+off2) && canMergeSym(sym1, sym2)
 	// result: (MOVBQSXload [off1+off2] {mergeSym(sym1,sym2)} base mem)
@@ -3539,7 +3561,7 @@ func rewriteValueAMD64_OpAMD64MOVBload(v *Value, config *Config) bool {
 	_ = b
 	// match: (MOVBload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _))
 	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
-	// result: x
+	// result: (MOVBQZX x)
 	for {
 		off := v.AuxInt
 		sym := v.Aux
@@ -3555,8 +3577,7 @@ func rewriteValueAMD64_OpAMD64MOVBload(v *Value, config *Config) bool {
 		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
 			break
 		}
-		v.reset(OpCopy)
-		v.Type = x.Type
+		v.reset(OpAMD64MOVBQZX)
 		v.AddArg(x)
 		return true
 	}
@@ -4834,6 +4855,28 @@ func rewriteValueAMD64_OpAMD64MOVLQSX(v *Value, config *Config) bool {
 func rewriteValueAMD64_OpAMD64MOVLQSXload(v *Value, config *Config) bool {
 	b := v.Block
 	_ = b
+	// match: (MOVLQSXload [off] {sym} ptr (MOVLstore [off2] {sym2} ptr2 x _))
+	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
+	// result: (MOVLQSX x)
+	for {
+		off := v.AuxInt
+		sym := v.Aux
+		ptr := v.Args[0]
+		v_1 := v.Args[1]
+		if v_1.Op != OpAMD64MOVLstore {
+			break
+		}
+		off2 := v_1.AuxInt
+		sym2 := v_1.Aux
+		ptr2 := v_1.Args[0]
+		x := v_1.Args[1]
+		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
+			break
+		}
+		v.reset(OpAMD64MOVLQSX)
+		v.AddArg(x)
+		return true
+	}
 	// match: (MOVLQSXload [off1] {sym1} (LEAQ [off2] {sym2} base) mem)
 	// cond: is32Bit(off1+off2) && canMergeSym(sym1, sym2)
 	// result: (MOVLQSXload [off1+off2] {mergeSym(sym1,sym2)} base mem)
@@ -5041,7 +5084,7 @@ func rewriteValueAMD64_OpAMD64MOVLload(v *Value, config *Config) bool {
 	_ = b
 	// match: (MOVLload [off] {sym} ptr (MOVLstore [off2] {sym2} ptr2 x _))
 	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
-	// result: x
+	// result: (MOVLQZX x)
 	for {
 		off := v.AuxInt
 		sym := v.Aux
@@ -5057,8 +5100,7 @@ func rewriteValueAMD64_OpAMD64MOVLload(v *Value, config *Config) bool {
 		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
 			break
 		}
-		v.reset(OpCopy)
-		v.Type = x.Type
+		v.reset(OpAMD64MOVLQZX)
 		v.AddArg(x)
 		return true
 	}
@@ -8703,6 +8745,28 @@ func rewriteValueAMD64_OpAMD64MOVWQSX(v *Value, config *Config) bool {
 func rewriteValueAMD64_OpAMD64MOVWQSXload(v *Value, config *Config) bool {
 	b := v.Block
 	_ = b
+	// match: (MOVWQSXload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _))
+	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
+	// result: (MOVWQSX x)
+	for {
+		off := v.AuxInt
+		sym := v.Aux
+		ptr := v.Args[0]
+		v_1 := v.Args[1]
+		if v_1.Op != OpAMD64MOVWstore {
+			break
+		}
+		off2 := v_1.AuxInt
+		sym2 := v_1.Aux
+		ptr2 := v_1.Args[0]
+		x := v_1.Args[1]
+		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
+			break
+		}
+		v.reset(OpAMD64MOVWQSX)
+		v.AddArg(x)
+		return true
+	}
 	// match: (MOVWQSXload [off1] {sym1} (LEAQ [off2] {sym2} base) mem)
 	// cond: is32Bit(off1+off2) && canMergeSym(sym1, sym2)
 	// result: (MOVWQSXload [off1+off2] {mergeSym(sym1,sym2)} base mem)
@@ -8883,7 +8947,7 @@ func rewriteValueAMD64_OpAMD64MOVWload(v *Value, config *Config) bool {
 	_ = b
 	// match: (MOVWload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _))
 	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
-	// result: x
+	// result: (MOVWQZX x)
 	for {
 		off := v.AuxInt
 		sym := v.Aux
@@ -8899,8 +8963,7 @@ func rewriteValueAMD64_OpAMD64MOVWload(v *Value, config *Config) bool {
 		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
 			break
 		}
-		v.reset(OpCopy)
-		v.Type = x.Type
+		v.reset(OpAMD64MOVWQZX)
 		v.AddArg(x)
 		return true
 	}

src/cmd/compile/internal/ssa/rewriteARM.go

@@ -5188,8 +5188,8 @@ func rewriteValueARM_OpARMMOVBUload(v *Value, config *Config) bool {
 		return true
 	}
 	// match: (MOVBUload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _))
-	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && !isSigned(x.Type)
-	// result: x
+	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
+	// result: (MOVBUreg x)
 	for {
 		off := v.AuxInt
 		sym := v.Aux
@@ -5202,11 +5202,10 @@ func rewriteValueARM_OpARMMOVBUload(v *Value, config *Config) bool {
 		sym2 := v_1.Aux
 		ptr2 := v_1.Args[0]
 		x := v_1.Args[1]
-		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && !isSigned(x.Type)) {
+		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
 			break
 		}
-		v.reset(OpCopy)
-		v.Type = x.Type
+		v.reset(OpARMMOVBUreg)
 		v.AddArg(x)
 		return true
 	}
@@ -5317,8 +5316,8 @@ func rewriteValueARM_OpARMMOVBload(v *Value, config *Config) bool {
 		return true
 	}
 	// match: (MOVBload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _))
-	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && isSigned(x.Type)
-	// result: x
+	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
+	// result: (MOVBreg x)
 	for {
 		off := v.AuxInt
 		sym := v.Aux
@@ -5331,11 +5330,10 @@ func rewriteValueARM_OpARMMOVBload(v *Value, config *Config) bool {
 		sym2 := v_1.Aux
 		ptr2 := v_1.Args[0]
 		x := v_1.Args[1]
-		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && isSigned(x.Type)) {
+		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
 			break
 		}
-		v.reset(OpCopy)
-		v.Type = x.Type
+		v.reset(OpARMMOVBreg)
 		v.AddArg(x)
 		return true
 	}
@@ -5836,8 +5834,8 @@ func rewriteValueARM_OpARMMOVHUload(v *Value, config *Config) bool {
 		return true
 	}
 	// match: (MOVHUload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _))
-	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && !isSigned(x.Type)
-	// result: x
+	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
+	// result: (MOVHUreg x)
 	for {
 		off := v.AuxInt
 		sym := v.Aux
@@ -5850,11 +5848,10 @@ func rewriteValueARM_OpARMMOVHUload(v *Value, config *Config) bool {
 		sym2 := v_1.Aux
 		ptr2 := v_1.Args[0]
 		x := v_1.Args[1]
-		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && !isSigned(x.Type)) {
+		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
 			break
 		}
-		v.reset(OpCopy)
-		v.Type = x.Type
+		v.reset(OpARMMOVHUreg)
 		v.AddArg(x)
 		return true
 	}
@@ -5989,8 +5986,8 @@ func rewriteValueARM_OpARMMOVHload(v *Value, config *Config) bool {
 		return true
 	}
 	// match: (MOVHload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _))
-	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && isSigned(x.Type)
-	// result: x
+	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
+	// result: (MOVHreg x)
 	for {
 		off := v.AuxInt
 		sym := v.Aux
@@ -6003,11 +6000,10 @@ func rewriteValueARM_OpARMMOVHload(v *Value, config *Config) bool {
 		sym2 := v_1.Aux
 		ptr2 := v_1.Args[0]
 		x := v_1.Args[1]
-		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && isSigned(x.Type)) {
+		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
 			break
 		}
-		v.reset(OpCopy)
-		v.Type = x.Type
+		v.reset(OpARMMOVHreg)
 		v.AddArg(x)
 		return true
 	}

src/cmd/compile/internal/ssa/rewriteMIPS.go

@@ -3332,8 +3332,8 @@ func rewriteValueMIPS_OpMIPSMOVBUload(v *Value, config *Config) bool {
 		return true
 	}
 	// match: (MOVBUload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _))
-	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && !isSigned(x.Type)
-	// result: x
+	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
+	// result: (MOVBUreg x)
 	for {
 		off := v.AuxInt
 		sym := v.Aux
@@ -3346,11 +3346,10 @@ func rewriteValueMIPS_OpMIPSMOVBUload(v *Value, config *Config) bool {
 		sym2 := v_1.Aux
 		ptr2 := v_1.Args[0]
 		x := v_1.Args[1]
-		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && !isSigned(x.Type)) {
+		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
 			break
 		}
-		v.reset(OpCopy)
-		v.Type = x.Type
+		v.reset(OpMIPSMOVBUreg)
 		v.AddArg(x)
 		return true
 	}
@@ -3490,8 +3489,8 @@ func rewriteValueMIPS_OpMIPSMOVBload(v *Value, config *Config) bool {
 		return true
 	}
 	// match: (MOVBload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _))
-	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && isSigned(x.Type)
-	// result: x
+	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
+	// result: (MOVBreg x)
 	for {
 		off := v.AuxInt
 		sym := v.Aux
@@ -3504,11 +3503,10 @@ func rewriteValueMIPS_OpMIPSMOVBload(v *Value, config *Config) bool {
 		sym2 := v_1.Aux
 		ptr2 := v_1.Args[0]
 		x := v_1.Args[1]
-		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && isSigned(x.Type)) {
+		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
 			break
 		}
-		v.reset(OpCopy)
-		v.Type = x.Type
+		v.reset(OpMIPSMOVBreg)
 		v.AddArg(x)
 		return true
 	}
@@ -4148,8 +4146,8 @@ func rewriteValueMIPS_OpMIPSMOVHUload(v *Value, config *Config) bool {
 		return true
 	}
 	// match: (MOVHUload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _))
-	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && !isSigned(x.Type)
-	// result: x
+	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
+	// result: (MOVHUreg x)
 	for {
 		off := v.AuxInt
 		sym := v.Aux
@@ -4162,11 +4160,10 @@ func rewriteValueMIPS_OpMIPSMOVHUload(v *Value, config *Config) bool {
 		sym2 := v_1.Aux
 		ptr2 := v_1.Args[0]
 		x := v_1.Args[1]
-		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && !isSigned(x.Type)) {
+		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
 			break
 		}
-		v.reset(OpCopy)
-		v.Type = x.Type
+		v.reset(OpMIPSMOVHUreg)
 		v.AddArg(x)
 		return true
 	}
@@ -4330,8 +4327,8 @@ func rewriteValueMIPS_OpMIPSMOVHload(v *Value, config *Config) bool {
 		return true
 	}
 	// match: (MOVHload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _))
-	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && isSigned(x.Type)
-	// result: x
+	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
+	// result: (MOVHreg x)
 	for {
 		off := v.AuxInt
 		sym := v.Aux
@@ -4344,11 +4341,10 @@ func rewriteValueMIPS_OpMIPSMOVHload(v *Value, config *Config) bool {
 		sym2 := v_1.Aux
 		ptr2 := v_1.Args[0]
 		x := v_1.Args[1]
-		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2) && isSigned(x.Type)) {
+		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
 			break
 		}
-		v.reset(OpCopy)
-		v.Type = x.Type
+		v.reset(OpMIPSMOVHreg)
 		v.AddArg(x)
 		return true
 	}

src/cmd/compile/internal/ssa/rewriteS390X.go

@@ -7851,7 +7851,7 @@ func rewriteValueS390X_OpS390XMOVBZload(v *Value, config *Config) bool {
 	_ = b
 	// match: (MOVBZload [off] {sym} ptr (MOVBstore [off2] {sym2} ptr2 x _))
 	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
-	// result: (MOVDreg x)
+	// result: (MOVBZreg x)
 	for {
 		off := v.AuxInt
 		sym := v.Aux
@@ -7867,7 +7867,7 @@ func rewriteValueS390X_OpS390XMOVBZload(v *Value, config *Config) bool {
 		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
 			break
 		}
-		v.reset(OpS390XMOVDreg)
+		v.reset(OpS390XMOVBZreg)
 		v.AddArg(x)
 		return true
 	}
@@ -11021,7 +11021,7 @@ func rewriteValueS390X_OpS390XMOVHZload(v *Value, config *Config) bool {
 	_ = b
 	// match: (MOVHZload [off] {sym} ptr (MOVHstore [off2] {sym2} ptr2 x _))
 	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
-	// result: (MOVDreg x)
+	// result: (MOVHZreg x)
 	for {
 		off := v.AuxInt
 		sym := v.Aux
@@ -11037,7 +11037,7 @@ func rewriteValueS390X_OpS390XMOVHZload(v *Value, config *Config) bool {
 		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
 			break
 		}
-		v.reset(OpS390XMOVDreg)
+		v.reset(OpS390XMOVHZreg)
 		v.AddArg(x)
 		return true
 	}
@@ -12406,7 +12406,7 @@ func rewriteValueS390X_OpS390XMOVWZload(v *Value, config *Config) bool {
 	_ = b
 	// match: (MOVWZload [off] {sym} ptr (MOVWstore [off2] {sym2} ptr2 x _))
 	// cond: sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)
-	// result: (MOVDreg x)
+	// result: (MOVWZreg x)
 	for {
 		off := v.AuxInt
 		sym := v.Aux
@@ -12422,7 +12422,7 @@ func rewriteValueS390X_OpS390XMOVWZload(v *Value, config *Config) bool {
 		if !(sym == sym2 && off == off2 && isSamePtr(ptr, ptr2)) {
 			break
 		}
-		v.reset(OpS390XMOVDreg)
+		v.reset(OpS390XMOVWZreg)
 		v.AddArg(x)
 		return true
 	}

src/cmd/compile/internal/syntax/nodes.go

@@ -74,7 +74,6 @@ type (
 	// Name Type
 	TypeDecl struct {
 		Name   *Name
-		Alias  bool
 		Type   Expr
 		Group  *Group // nil means not part of a group
 		Pragma Pragma

src/cmd/compile/internal/syntax/parser.go

@@ -325,7 +325,7 @@ func (p *parser) constDecl(group *Group) Decl {
 	return d
 }
 
-// TypeSpec = identifier [ "=" ] Type .
+// TypeSpec = identifier Type .
 func (p *parser) typeDecl(group *Group) Decl {
 	if trace {
 		defer p.trace("typeDecl")()
@@ -335,7 +335,6 @@ func (p *parser) typeDecl(group *Group) Decl {
 	d.init(p)
 
 	d.Name = p.name()
-	d.Alias = p.got(_Assign)
 	d.Type = p.tryType()
 	if d.Type == nil {
 		p.syntax_error("in type declaration")

src/cmd/compile/internal/syntax/printer.go

@@ -619,11 +619,7 @@ func (p *printer) printRawNode(n Node) {
 		if n.Group == nil {
 			p.print(_Type, blank)
 		}
-		p.print(n.Name, blank)
-		if n.Alias {
-			p.print(_Assign, blank)
-		}
-		p.print(n.Type)
+		p.print(n.Name, blank, n.Type)
 
 	case *VarDecl:
 		if n.Group == nil {

src/cmd/compile/internal/syntax/printer_test.go

@@ -22,20 +22,3 @@ func TestPrint(t *testing.T) {
 	Fprint(os.Stdout, ast, true)
 	fmt.Println()
 }
-
-func TestPrintString(t *testing.T) {
-	for _, want := range []string{
-		"package p",
-		"package p; type _ = int; type T1 = struct{}; type ( _ = *struct{}; T2 = float32 )",
-		// TODO(gri) expand
-	} {
-		ast, err := ParseBytes([]byte(want), nil, nil, 0)
-		if err != nil {
-			t.Error(err)
-			continue
-		}
-		if got := String(ast); got != want {
-			t.Errorf("%q: got %q", want, got)
-		}
-	}
-}

src/cmd/dist/build.go

@@ -701,7 +701,7 @@ func install(dir string) {
 	} else {
 		archive = b
 	}
-	compile := []string{pathf("%s/compile", tooldir), "-pack", "-o", b, "-p", pkg}
+	compile := []string{pathf("%s/compile", tooldir), "-std", "-pack", "-o", b, "-p", pkg}
 	if gogcflags != "" {
 		compile = append(compile, strings.Fields(gogcflags)...)
 	}

src/cmd/dist/test.go

@@ -600,7 +600,6 @@ func (t *tester) registerTests() {
 			})
 		}
 	}
-	return // skip API check on go1.8.typealias branch
 	if t.goos != "nacl" && t.goos != "android" && !t.iOS() {
 		t.tests = append(t.tests, distTest{
 			name:    "api",

src/cmd/doc/doc_test.go

@@ -71,7 +71,6 @@ var tests = []test{
 			`const MultiLineConst = ...`,                                   // Multi line constant.
 			`var MultiLineVar = map\[struct{ ... }\]struct{ ... }{ ... }`,  // Multi line variable.
 			`func MultiLineFunc\(x interface{ ... }\) \(r struct{ ... }\)`, // Multi line function.
-			`type T1 = T2`, // Type alias
 		},
 		[]string{
 			`const internalConstant = 2`,        // No internal constants.
@@ -90,7 +89,6 @@ var tests = []test{
 			`unexportedTypedConstant`,           // No unexported typed constant.
 			`Field`,                             // No fields.
 			`Method`,                            // No methods.
-			`type T1 T2`, // Type alias does not display as type declaration.
 		},
 	},
 	// Package dump -u
@@ -267,18 +265,6 @@ var tests = []test{
 			`error`,                          // No embedded error.
 		},
 	},
-	// Type T1 dump (alias).
-	{
-		"type T1",
-		[]string{p+".T1"},
-		[]string{
-			`type T1 = T2`,
-		},
-		[]string{
-			`type T1 T2`,
-			`type ExportedType`,
-		},
-	},
 	// Type -u with unexported fields.
 	{
 		"type with unexported fields and -u",

src/cmd/doc/pkg.go

@@ -258,11 +258,7 @@ func (pkg *Package) oneLineNodeDepth(node ast.Node, depth int) string {
 		return fmt.Sprintf("func %s%s%s", recv, name, fnc)
 
 	case *ast.TypeSpec:
-		sep := " "
-		if n.Assign.IsValid() {
-			sep = " = "
-		}
-		return fmt.Sprintf("type %s%s%s", n.Name.Name, sep, pkg.oneLineNodeDepth(n.Type, depth))
+		return fmt.Sprintf("type %s %s", n.Name.Name, pkg.oneLineNodeDepth(n.Type, depth))
 
 	case *ast.FuncType:
 		var params []string

src/cmd/doc/testdata/pkg.go

@@ -172,7 +172,3 @@ const (
 )
 
 const ConstGroup4 ExportedType = ExportedType{}
-
-type T2 int
-
-type T1 = T2

src/cmd/go/alldocs.go

@@ -1103,17 +1103,26 @@
 // 	CGO_CFLAGS
 // 		Flags that cgo will pass to the compiler when compiling
 // 		C code.
-// 	CGO_CPPFLAGS
-// 		Flags that cgo will pass to the compiler when compiling
-// 		C or C++ code.
-// 	CGO_CXXFLAGS
-// 		Flags that cgo will pass to the compiler when compiling
-// 		C++ code.
-// 	CGO_FFLAGS
-// 		Flags that cgo will pass to the compiler when compiling
-// 		Fortran code.
-// 	CGO_LDFLAGS
-// 		Flags that cgo will pass to the compiler when linking.
+// 	CGO_CFLAGS_ALLOW
+// 		A regular expression specifying additional flags to allow
+// 		to appear in #cgo CFLAGS source code directives.
+// 		Does not apply to the CGO_CFLAGS environment variable.
+// 	CGO_CFLAGS_DISALLOW
+// 		A regular expression specifying flags that must be disallowed
+// 		from appearing in #cgo CFLAGS source code directives.
+// 		Does not apply to the CGO_CFLAGS environment variable.
+// 	CGO_CPPFLAGS, CGO_CPPFLAGS_ALLOW, CGO_CPPFLAGS_DISALLOW
+// 		Like CGO_CFLAGS, CGO_CFLAGS_ALLOW, and CGO_CFLAGS_DISALLOW,
+// 		but for the C preprocessor.
+// 	CGO_CXXFLAGS, CGO_CXXFLAGS_ALLOW, CGO_CXXFLAGS_DISALLOW
+// 		Like CGO_CFLAGS, CGO_CFLAGS_ALLOW, and CGO_CFLAGS_DISALLOW,
+// 		but for the C++ compiler.
+// 	CGO_FFLAGS, CGO_FFLAGS_ALLOW, CGO_FFLAGS_DISALLOW
+// 		Like CGO_CFLAGS, CGO_CFLAGS_ALLOW, and CGO_CFLAGS_DISALLOW,
+// 		but for the Fortran compiler.
+// 	CGO_LDFLAGS, CGO_LDFLAGS_ALLOW, CGO_LDFLAGS_DISALLOW
+// 		Like CGO_CFLAGS, CGO_CFLAGS_ALLOW, and CGO_CFLAGS_DISALLOW,
+// 		but for the linker.
 // 	CXX
 // 		The command to use to compile C++ code.
 // 	PKG_CONFIG

src/cmd/go/build.go

@@ -1670,26 +1670,35 @@ func splitPkgConfigOutput(out []byte) []string {
 // Calls pkg-config if needed and returns the cflags/ldflags needed to build the package.
 func (b *builder) getPkgConfigFlags(p *Package) (cflags, ldflags []string, err error) {
 	if pkgs := p.CgoPkgConfig; len(pkgs) > 0 {
+		for _, pkg := range pkgs {
+			if !SafeArg(pkg) {
+				return nil, nil, fmt.Errorf("invalid pkg-config package name: %s", pkg)
+			}
+		}
 		var out []byte
-		out, err = b.runOut(p.Dir, p.ImportPath, nil, b.pkgconfigCmd(), "--cflags", pkgs)
+		out, err = b.runOut(p.Dir, p.ImportPath, nil, b.pkgconfigCmd(), "--cflags", "--", pkgs)
 		if err != nil {
 			b.showOutput(p.Dir, b.pkgconfigCmd()+" --cflags "+strings.Join(pkgs, " "), string(out))
 			b.print(err.Error() + "\n")
-			err = errPrintedOutput
-			return
+			return nil, nil, errPrintedOutput
 		}
 		if len(out) > 0 {
 			cflags = splitPkgConfigOutput(out)
+			if err := checkCompilerFlags("CFLAGS", "pkg-config --cflags", cflags); err != nil {
+				return nil, nil, err
+			}
 		}
-		out, err = b.runOut(p.Dir, p.ImportPath, nil, b.pkgconfigCmd(), "--libs", pkgs)
+		out, err = b.runOut(p.Dir, p.ImportPath, nil, b.pkgconfigCmd(), "--libs", "--", pkgs)
 		if err != nil {
 			b.showOutput(p.Dir, b.pkgconfigCmd()+" --libs "+strings.Join(pkgs, " "), string(out))
 			b.print(err.Error() + "\n")
-			err = errPrintedOutput
-			return
+			return nil, nil, errPrintedOutput
 		}
 		if len(out) > 0 {
 			ldflags = strings.Fields(string(out))
+			if err := checkLinkerFlags("CFLAGS", "pkg-config --cflags", ldflags); err != nil {
+				return nil, nil, err
+			}
 		}
 	}
 	return
@@ -2117,6 +2126,17 @@ func (b *builder) processOutput(out []byte) string {
 // It returns the command output and any errors that occurred.
 func (b *builder) runOut(dir string, desc string, env []string, cmdargs ...interface{}) ([]byte, error) {
 	cmdline := stringList(cmdargs...)
+
+	for _, arg := range cmdline {
+		// GNU binutils commands, including gcc and gccgo, interpret an argument
+		// @foo anywhere in the command line (even following --) as meaning
+		// "read and insert arguments from the file named foo."
+		// Don't say anything that might be misinterpreted that way.
+		if strings.HasPrefix(arg, "@") {
+			return nil, fmt.Errorf("invalid command-line argument %s in command: %s", arg, joinUnambiguously(cmdline))
+		}
+	}
+
 	if buildN || buildX {
 		var envcmdline string
 		for i := range env {
@@ -2357,6 +2377,9 @@ func (gcToolchain) gc(b *builder, p *Package, archive, obj string, asmhdr bool,
 		// additional reflect type data.
 		gcargs = append(gcargs, "-+")
 	}
+	if p.Standard {
+		gcargs = append(gcargs, "-std")
+	}
 
 	// If we're giving the compiler the entire package (no C etc files), tell it that,
 	// so that it can give good error messages about forward declarations.
@@ -3255,23 +3278,45 @@ func envList(key, def string) []string {
 	return strings.Fields(v)
 }
 
-// Return the flags to use when invoking the C, C++ or Fortran compilers, or cgo.
-func (b *builder) cflags(p *Package) (cppflags, cflags, cxxflags, fflags, ldflags []string) {
+// CFlags returns the flags to use when invoking the C, C++ or Fortran compilers, or cgo.
+func (b *builder) cflags(p *Package) (cppflags, cflags, cxxflags, fflags, ldflags []string, err error) {
 	defaults := "-g -O2"
 
-	cppflags = stringList(envList("CGO_CPPFLAGS", ""), p.CgoCPPFLAGS)
-	cflags = stringList(envList("CGO_CFLAGS", defaults), p.CgoCFLAGS)
-	cxxflags = stringList(envList("CGO_CXXFLAGS", defaults), p.CgoCXXFLAGS)
-	fflags = stringList(envList("CGO_FFLAGS", defaults), p.CgoFFLAGS)
-	ldflags = stringList(envList("CGO_LDFLAGS", defaults), p.CgoLDFLAGS)
+	if cppflags, err = buildFlags("CPPFLAGS", "", p.CgoCPPFLAGS, checkCompilerFlags); err != nil {
+		return
+	}
+	if cflags, err = buildFlags("CFLAGS", defaults, p.CgoCFLAGS, checkCompilerFlags); err != nil {
+		return
+	}
+	if cxxflags, err = buildFlags("CXXFLAGS", defaults, p.CgoCXXFLAGS, checkCompilerFlags); err != nil {
+		return
+	}
+	if fflags, err = buildFlags("FFLAGS", defaults, p.CgoFFLAGS, checkCompilerFlags); err != nil {
+		return
+	}
+	if ldflags, err = buildFlags("LDFLAGS", defaults, p.CgoLDFLAGS, checkLinkerFlags); err != nil {
+		return
+	}
+
 	return
 }
 
+func buildFlags(name, defaults string, fromPackage []string, check func(string, string, []string) error) ([]string, error) {
+	if err := check(name, "#cgo "+name, fromPackage); err != nil {
+		return nil, err
+	}
+	return stringList(envList("CGO_"+name, defaults), fromPackage), nil
+}
+
 var cgoRe = regexp.MustCompile(`[/\\:]`)
 
 func (b *builder) cgo(a *action, cgoExe, obj string, pcCFLAGS, pcLDFLAGS, cgofiles, objdirCgofiles, gccfiles, gxxfiles, mfiles, ffiles []string) (outGo, outObj []string, err error) {
 	p := a.p
-	cgoCPPFLAGS, cgoCFLAGS, cgoCXXFLAGS, cgoFFLAGS, cgoLDFLAGS := b.cflags(p)
+	cgoCPPFLAGS, cgoCFLAGS, cgoCXXFLAGS, cgoFFLAGS, cgoLDFLAGS, err := b.cflags(p)
+	if err != nil {
+		return nil, nil, err
+	}
+
 	cgoCPPFLAGS = append(cgoCPPFLAGS, pcCFLAGS...)
 	cgoLDFLAGS = append(cgoLDFLAGS, pcLDFLAGS...)
 	// If we are compiling Objective-C code, then we need to link against libobjc
@@ -3335,6 +3380,12 @@ func (b *builder) cgo(a *action, cgoExe, obj string, pcCFLAGS, pcLDFLAGS, cgofil
 	}
 
 	// Update $CGO_LDFLAGS with p.CgoLDFLAGS.
+	// These flags are recorded in the generated _cgo_gotypes.go file
+	// using //go:cgo_ldflag directives, the compiler records them in the
+	// object file for the package, and then the Go linker passes them
+	// along to the host linker. At this point in the code, cgoLDFLAGS
+	// consists of the original $CGO_LDFLAGS (unchecked) and all the
+	// flags put together from source code (checked).
 	var cgoenv []string
 	if len(cgoLDFLAGS) > 0 {
 		flags := make([]string, len(cgoLDFLAGS))
@@ -3684,7 +3735,11 @@ func (b *builder) swigIntSize(obj string) (intsize string, err error) {
 
 // Run SWIG on one SWIG input file.
 func (b *builder) swigOne(p *Package, file, obj string, pcCFLAGS []string, cxx bool, intgosize string) (outGo, outC string, err error) {
-	cgoCPPFLAGS, cgoCFLAGS, cgoCXXFLAGS, _, _ := b.cflags(p)
+	cgoCPPFLAGS, cgoCFLAGS, cgoCXXFLAGS, _, _, err := b.cflags(p)
+	if err != nil {
+		return "", "", err
+	}
+
 	var cflags []string
 	if cxx {
 		cflags = stringList(cgoCPPFLAGS, pcCFLAGS, cgoCXXFLAGS)

src/cmd/go/env.go

@@ -90,7 +90,12 @@ func findEnv(env []envVar, name string) string {
 func extraEnvVars() []envVar {
 	var b builder
 	b.init()
-	cppflags, cflags, cxxflags, fflags, ldflags := b.cflags(&Package{})
+	cppflags, cflags, cxxflags, fflags, ldflags, err := b.cflags(&Package{})
+	if err != nil {
+		// Should not happen - b.CFlags was given an empty package.
+		fmt.Fprintf(os.Stderr, "go: invalid cflags: %v\n", err)
+		return nil
+	}
 	return []envVar{
 		{"PKG_CONFIG", b.pkgconfigCmd()},
 		{"CGO_CFLAGS", strings.Join(cflags, " ")},

src/cmd/go/get.go

@@ -439,6 +439,11 @@ func downloadPackage(p *Package) error {
 		p.build.PkgRoot = filepath.Join(list[0], "pkg")
 	}
 	root := filepath.Join(p.build.SrcRoot, filepath.FromSlash(rootPath))
+
+	if err := checkNestedVCS(vcs, root, p.build.SrcRoot); err != nil {
+		return err
+	}
+
 	// If we've considered this repository already, don't do it again.
 	if downloadRootCache[root] {
 		return nil

src/cmd/go/go_test.go

@@ -1120,7 +1120,7 @@ func testMove(t *testing.T, vcs, url, base, config string) {
 	tg.runFail("get", "-d", "-u", url)
 	tg.grepStderr("is a custom import path for", "go get -d -u "+url+" failed for wrong reason")
 	tg.runFail("get", "-d", "-f", "-u", url)
-	tg.grepStderr("validating server certificate|not found", "go get -d -f -u "+url+" failed for wrong reason")
+	tg.grepStderr("validating server certificate|[nN]ot [fF]ound", "go get -d -f -u "+url+" failed for wrong reason")
 }
 
 func TestInternalPackageErrorsAreHandled(t *testing.T) {
@@ -1141,10 +1141,9 @@ func TestMoveGit(t *testing.T) {
 	testMove(t, "git", "rsc.io/pdf", "pdf", "rsc.io/pdf/.git/config")
 }
 
-// TODO(rsc): Set up a test case on bitbucket for hg.
-// func TestMoveHG(t *testing.T) {
-// 	testMove(t, "hg", "rsc.io/x86/x86asm", "x86", "rsc.io/x86/.hg/hgrc")
-// }
+func TestMoveHG(t *testing.T) {
+	testMove(t, "hg", "vcs-test.golang.org/go/custom-hg-hello", "custom-hg-hello", "vcs-test.golang.org/go/custom-hg-hello/.hg/hgrc")
+}
 
 // TODO(rsc): Set up a test case on SourceForge (?) for svn.
 // func testMoveSVN(t *testing.T) {
@@ -1273,6 +1272,25 @@ func TestGetGitDefaultBranch(t *testing.T) {
 	tg.grepStdout(`\* another-branch`, "not on correct default branch")
 }
 
+func TestAccidentalGitCheckout(t *testing.T) {
+	testenv.MustHaveExternalNetwork(t)
+	if _, err := exec.LookPath("git"); err != nil {
+		t.Skip("skipping because git binary not found")
+	}
+
+	tg := testgo(t)
+	defer tg.cleanup()
+	tg.parallel()
+	tg.tempDir("src")
+	tg.setenv("GOPATH", tg.path("."))
+
+	tg.runFail("get", "-u", "vcs-test.golang.org/go/test1-svn-git")
+	tg.grepStderr("src[\\\\/]vcs-test.* uses git, but parent .*src[\\\\/]vcs-test.* uses svn", "get did not fail for right reason")
+
+	tg.runFail("get", "-u", "vcs-test.golang.org/go/test2-svn-git/test2main")
+	tg.grepStderr("src[\\\\/]vcs-test.* uses git, but parent .*src[\\\\/]vcs-test.* uses svn", "get did not fail for right reason")
+}
+
 func TestErrorMessageForSyntaxErrorInTestGoFileSaysFAIL(t *testing.T) {
 	tg := testgo(t)
 	defer tg.cleanup()
@@ -2336,7 +2354,7 @@ func TestCgoHandlesWlORIGIN(t *testing.T) {
 	defer tg.cleanup()
 	tg.parallel()
 	tg.tempFile("src/origin/origin.go", `package origin
-		// #cgo !darwin LDFLAGS: -Wl,-rpath -Wl,$ORIGIN
+		// #cgo !darwin LDFLAGS: -Wl,-rpath,$ORIGIN
 		// void f(void) {}
 		import "C"
 		func f() { C.f() }`)
@@ -2719,7 +2737,7 @@ func TestImportMain(t *testing.T) {
 		func TestFoo(t *testing.T) {}
 	`)
 	tg.setenv("GOPATH", tg.path("."))
-	tg.creatingTemp("x")
+	tg.creatingTemp("x" + exeSuffix)
 	tg.run("build", "x")
 	tg.run("test", "x")
 
@@ -3773,3 +3791,150 @@ func TestA(t *testing.T) {}`)
 	tg.grepStdout("pkgs$", "expected package not listed")
 	tg.grepStdout("pkgs/a", "expected package not listed")
 }
+
+func TestBadCommandLines(t *testing.T) {
+	tg := testgo(t)
+	defer tg.cleanup()
+
+	tg.tempFile("src/x/x.go", "package x\n")
+	tg.setenv("GOPATH", tg.path("."))
+
+	tg.run("build", "x")
+
+	tg.tempFile("src/x/@y.go", "package x\n")
+	tg.runFail("build", "x")
+	tg.grepStderr("invalid input file name \"@y.go\"", "did not reject @y.go")
+	tg.must(os.Remove(tg.path("src/x/@y.go")))
+
+	tg.tempFile("src/x/-y.go", "package x\n")
+	tg.runFail("build", "x")
+	tg.grepStderr("invalid input file name \"-y.go\"", "did not reject -y.go")
+	tg.must(os.Remove(tg.path("src/x/-y.go")))
+
+	tg.runFail("build", "-gcflags=@x", "x")
+	tg.grepStderr("invalid command-line argument @x in command", "did not reject @x during exec")
+
+	tg.tempFile("src/@x/x.go", "package x\n")
+	tg.setenv("GOPATH", tg.path("."))
+	tg.runFail("build", "@x")
+	tg.grepStderr("invalid input directory name \"@x\"", "did not reject @x directory")
+
+	tg.tempFile("src/@x/y/y.go", "package y\n")
+	tg.setenv("GOPATH", tg.path("."))
+	tg.runFail("build", "@x/y")
+	tg.grepStderr("invalid import path \"@x/y\"", "did not reject @x/y import path")
+
+	tg.tempFile("src/-x/x.go", "package x\n")
+	tg.setenv("GOPATH", tg.path("."))
+	tg.runFail("build", "--", "-x")
+	tg.grepStderr("invalid input directory name \"-x\"", "did not reject -x directory")
+
+	tg.tempFile("src/-x/y/y.go", "package y\n")
+	tg.setenv("GOPATH", tg.path("."))
+	tg.runFail("build", "--", "-x/y")
+	tg.grepStderr("invalid import path \"-x/y\"", "did not reject -x/y import path")
+}
+
+func TestBadCgoDirectives(t *testing.T) {
+	if !canCgo {
+		t.Skip("no cgo")
+	}
+	tg := testgo(t)
+	defer tg.cleanup()
+
+	tg.tempFile("src/x/x.go", "package x\n")
+	tg.setenv("GOPATH", tg.path("."))
+
+	tg.tempFile("src/x/x.go", `package x
+
+		//go:cgo_ldflag "-fplugin=foo.so"
+
+	`)
+	tg.runFail("build", "x")
+	tg.grepStderr("//go:cgo_ldflag .* only allowed in cgo-generated code", "did not reject //go:cgo_ldflag directive")
+
+	tg.must(os.Remove(tg.path("src/x/x.go")))
+	tg.runFail("build", "x")
+	tg.grepStderr("no buildable Go source files", "did not report missing source code")
+	tg.tempFile("src/x/_cgo_yy.go", `package x
+
+		//go:cgo_ldflag "-fplugin=foo.so"
+
+	`)
+	tg.runFail("build", "x")
+	tg.grepStderr("no buildable Go source files", "did not report missing source code") // _* files are ignored...
+
+	tg.runFail("build", tg.path("src/x/_cgo_yy.go")) // ... but if forced, the comment is rejected
+	// Actually, today there is a separate issue that _ files named
+	// on the command-line are ignored. Once that is fixed,
+	// we want to see the cgo_ldflag error.
+	tg.grepStderr("//go:cgo_ldflag only allowed in cgo-generated code|no buildable Go source files", "did not reject //go:cgo_ldflag directive")
+	tg.must(os.Remove(tg.path("src/x/_cgo_yy.go")))
+
+	tg.tempFile("src/x/x.go", "package x\n")
+	tg.tempFile("src/x/y.go", `package x
+		// #cgo CFLAGS: -fplugin=foo.so
+		import "C"
+	`)
+	tg.runFail("build", "x")
+	tg.grepStderr("invalid flag in #cgo CFLAGS: -fplugin=foo.so", "did not reject -fplugin")
+
+	tg.tempFile("src/x/y.go", `package x
+		// #cgo CFLAGS: -Ibar -fplugin=foo.so
+		import "C"
+	`)
+	tg.runFail("build", "x")
+	tg.grepStderr("invalid flag in #cgo CFLAGS: -fplugin=foo.so", "did not reject -fplugin")
+
+	tg.tempFile("src/x/y.go", `package x
+		// #cgo pkg-config: -foo
+		import "C"
+	`)
+	tg.runFail("build", "x")
+	tg.grepStderr("invalid pkg-config package name: -foo", "did not reject pkg-config: -foo")
+
+	tg.tempFile("src/x/y.go", `package x
+		// #cgo pkg-config: @foo
+		import "C"
+	`)
+	tg.runFail("build", "x")
+	tg.grepStderr("invalid pkg-config package name: @foo", "did not reject pkg-config: -foo")
+
+	tg.tempFile("src/x/y.go", `package x
+		// #cgo CFLAGS: @foo
+		import "C"
+	`)
+	tg.runFail("build", "x")
+	tg.grepStderr("invalid flag in #cgo CFLAGS: @foo", "did not reject @foo flag")
+
+	tg.tempFile("src/x/y.go", `package x
+		// #cgo CFLAGS: -D
+		import "C"
+	`)
+	tg.runFail("build", "x")
+	tg.grepStderr("invalid flag in #cgo CFLAGS: -D without argument", "did not reject trailing -I flag")
+
+	// Note that -I @foo is allowed because we rewrite it into -I /path/to/src/@foo
+	// before the check is applied. There's no such rewrite for -D.
+
+	tg.tempFile("src/x/y.go", `package x
+		// #cgo CFLAGS: -D @foo
+		import "C"
+	`)
+	tg.runFail("build", "x")
+	tg.grepStderr("invalid flag in #cgo CFLAGS: -D @foo", "did not reject -D @foo flag")
+
+	tg.tempFile("src/x/y.go", `package x
+		// #cgo CFLAGS: -D@foo
+		import "C"
+	`)
+	tg.runFail("build", "x")
+	tg.grepStderr("invalid flag in #cgo CFLAGS: -D@foo", "did not reject -D@foo flag")
+
+	tg.setenv("CGO_CFLAGS", "-D@foo")
+	tg.tempFile("src/x/y.go", `package x
+		import "C"
+	`)
+	tg.run("build", "-n", "x")
+	tg.grepStderr("-D@foo", "did not find -D@foo in commands")
+}

src/cmd/go/help.go

@@ -468,17 +468,26 @@ Environment variables for use with cgo:
 	CGO_CFLAGS
 		Flags that cgo will pass to the compiler when compiling
 		C code.
-	CGO_CPPFLAGS
-		Flags that cgo will pass to the compiler when compiling
-		C or C++ code.
-	CGO_CXXFLAGS
-		Flags that cgo will pass to the compiler when compiling
-		C++ code.
-	CGO_FFLAGS
-		Flags that cgo will pass to the compiler when compiling
-		Fortran code.
-	CGO_LDFLAGS
-		Flags that cgo will pass to the compiler when linking.
+	CGO_CFLAGS_ALLOW
+		A regular expression specifying additional flags to allow
+		to appear in #cgo CFLAGS source code directives.
+		Does not apply to the CGO_CFLAGS environment variable.
+	CGO_CFLAGS_DISALLOW
+		A regular expression specifying flags that must be disallowed
+		from appearing in #cgo CFLAGS source code directives.
+		Does not apply to the CGO_CFLAGS environment variable.
+	CGO_CPPFLAGS, CGO_CPPFLAGS_ALLOW, CGO_CPPFLAGS_DISALLOW
+		Like CGO_CFLAGS, CGO_CFLAGS_ALLOW, and CGO_CFLAGS_DISALLOW,
+		but for the C preprocessor.
+	CGO_CXXFLAGS, CGO_CXXFLAGS_ALLOW, CGO_CXXFLAGS_DISALLOW
+		Like CGO_CFLAGS, CGO_CFLAGS_ALLOW, and CGO_CFLAGS_DISALLOW,
+		but for the C++ compiler.
+	CGO_FFLAGS, CGO_FFLAGS_ALLOW, CGO_FFLAGS_DISALLOW
+		Like CGO_CFLAGS, CGO_CFLAGS_ALLOW, and CGO_CFLAGS_DISALLOW,
+		but for the Fortran compiler.
+	CGO_LDFLAGS, CGO_LDFLAGS_ALLOW, CGO_LDFLAGS_DISALLOW
+		Like CGO_CFLAGS, CGO_CFLAGS_ALLOW, and CGO_CFLAGS_DISALLOW,
+		but for the linker.
 	CXX
 		The command to use to compile C++ code.
 	PKG_CONFIG

src/cmd/go/pkg.go

@@ -22,6 +22,7 @@ import (
 	"strconv"
 	"strings"
 	"unicode"
+	"unicode/utf8"
 )
 
 var ignoreImports bool // control whether we ignore imports in packages
@@ -47,6 +48,8 @@ type Package struct {
 	BinaryOnly    bool   `json:",omitempty"` // package cannot be recompiled
 
 	// Source files
+	// If you add to this list you MUST add to p.AllFiles (below) too.
+	// Otherwise file name security lists will not apply to any new additions.
 	GoFiles        []string `json:",omitempty"` // .go source files (excluding CgoFiles, TestGoFiles, XTestGoFiles)
 	CgoFiles       []string `json:",omitempty"` // .go sources files that import "C"
 	IgnoredGoFiles []string `json:",omitempty"` // .go sources ignored due to build constraints
@@ -78,6 +81,8 @@ type Package struct {
 	DepsErrors []*PackageError `json:",omitempty"` // errors loading dependencies
 
 	// Test information
+	// If you add to this list you MUST add to p.AllFiles (below) too.
+	// Otherwise file name security lists will not apply to any new additions.
 	TestGoFiles  []string `json:",omitempty"` // _test.go files in package
 	TestImports  []string `json:",omitempty"` // imports from TestGoFiles
 	XTestGoFiles []string `json:",omitempty"` // _test.go files outside package
@@ -106,6 +111,30 @@ type Package struct {
 	gobinSubdir  bool                 // install target would be subdir of GOBIN
 }
 
+// allFiles returns the names of all the files considered for the package.
+// This is used for sanity and security checks, so we include all files,
+// even IgnoredGoFiles, because some subcommands consider them.
+// The go/build package filtered others out (like foo_wrongGOARCH.s)
+// and that's OK.
+func (p *Package) allFiles() []string {
+	return stringList(
+		p.GoFiles,
+		p.CgoFiles,
+		p.IgnoredGoFiles,
+		p.CFiles,
+		p.CXXFiles,
+		p.MFiles,
+		p.HFiles,
+		p.FFiles,
+		p.SFiles,
+		p.SwigFiles,
+		p.SwigCXXFiles,
+		p.SysoFiles,
+		p.TestGoFiles,
+		p.XTestGoFiles,
+	)
+}
+
 // vendored returns the vendor-resolved version of imports,
 // which should be p.TestImports or p.XTestImports, NOT p.Imports.
 // The imports in p.TestImports and p.XTestImports are not recursively
@@ -990,22 +1019,8 @@ func (p *Package) load(stk *importStack, bp *build.Package, err error) *Package
 	// To avoid problems on case-insensitive files, we reject any package
 	// where two different input files have equal names under a case-insensitive
 	// comparison.
-	f1, f2 := foldDup(stringList(
-		p.GoFiles,
-		p.CgoFiles,
-		p.IgnoredGoFiles,
-		p.CFiles,
-		p.CXXFiles,
-		p.MFiles,
-		p.HFiles,
-		p.FFiles,
-		p.SFiles,
-		p.SysoFiles,
-		p.SwigFiles,
-		p.SwigCXXFiles,
-		p.TestGoFiles,
-		p.XTestGoFiles,
-	))
+	inputs := p.allFiles()
+	f1, f2 := foldDup(inputs)
 	if f1 != "" {
 		p.Error = &PackageError{
 			ImportStack: stk.copy(),
@@ -1014,6 +1029,37 @@ func (p *Package) load(stk *importStack, bp *build.Package, err error) *Package
 		return p
 	}
 
+	// If first letter of input file is ASCII, it must be alphanumeric.
+	// This avoids files turning into flags when invoking commands,
+	// and other problems we haven't thought of yet.
+	// Also, _cgo_ files must be generated by us, not supplied.
+	// They are allowed to have //go:cgo_ldflag directives.
+	// The directory scan ignores files beginning with _,
+	// so we shouldn't see any _cgo_ files anyway, but just be safe.
+	for _, file := range inputs {
+		if !SafeArg(file) || strings.HasPrefix(file, "_cgo_") {
+			p.Error = &PackageError{
+				ImportStack: stk.copy(),
+				Err:         fmt.Sprintf("invalid input file name %q", file),
+			}
+			return p
+		}
+	}
+	if name := pathpkg.Base(p.ImportPath); !SafeArg(name) {
+		p.Error = &PackageError{
+			ImportStack: stk.copy(),
+			Err:         fmt.Sprintf("invalid input directory name %q", name),
+		}
+		return p
+	}
+	if !SafeArg(p.ImportPath) {
+		p.Error = &PackageError{
+			ImportStack: stk.copy(),
+			Err:         fmt.Sprintf("invalid import path %q", p.ImportPath),
+		}
+		return p
+	}
+
 	// Build list of imported packages and full dependency list.
 	imports := make([]*Package, 0, len(p.Imports))
 	deps := make(map[string]*Package)
@@ -1130,6 +1176,22 @@ func (p *Package) load(stk *importStack, bp *build.Package, err error) *Package
 	return p
 }
 
+// SafeArg reports whether arg is a "safe" command-line argument,
+// meaning that when it appears in a command-line, it probably
+// doesn't have some special meaning other than its own name.
+// Obviously args beginning with - are not safe (they look like flags).
+// Less obviously, args beginning with @ are not safe (they look like
+// GNU binutils flagfile specifiers, sometimes called "response files").
+// To be conservative, we reject almost any arg beginning with non-alphanumeric ASCII.
+// We accept leading . _ and / as likely in file system paths.
+func SafeArg(name string) bool {
+	if name == "" {
+		return false
+	}
+	c := name[0]
+	return '0' <= c && c <= '9' || 'A' <= c && c <= 'Z' || 'a' <= c && c <= 'z' || c == '.' || c == '_' || c == '/' || c >= utf8.RuneSelf
+}
+
 // usesSwig reports whether the package needs to run SWIG.
 func (p *Package) usesSwig() bool {
 	return len(p.SwigFiles) > 0 || len(p.SwigCXXFiles) > 0

src/cmd/go/security.go

@@ -0,0 +1,159 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Checking of compiler and linker flags.
+// We must avoid flags like -fplugin=, which can allow
+// arbitrary code execution during the build.
+// Do not make changes here without carefully
+// considering the implications.
+// (That's why the code is isolated in a file named security.go.)
+//
+// Note that -Wl,foo means split foo on commas and pass to
+// the linker, so that -Wl,-foo,bar means pass -foo bar to
+// the linker. Similarly -Wa,foo for the assembler and so on.
+// If any of these are permitted, the wildcard portion must
+// disallow commas.
+//
+// Note also that GNU binutils accept any argument @foo
+// as meaning "read more flags from the file foo", so we must
+// guard against any command-line argument beginning with @,
+// even things like "-I @foo".
+// We use load.SafeArg (which is even more conservative)
+// to reject these.
+//
+// Even worse, gcc -I@foo (one arg) turns into cc1 -I @foo (two args),
+// so although gcc doesn't expand the @foo, cc1 will.
+// So out of paranoia, we reject @ at the beginning of every
+// flag argument that might be split into its own argument.
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"regexp"
+)
+
+var re = regexp.MustCompile
+
+var validCompilerFlags = []*regexp.Regexp{
+	re(`-D([A-Za-z_].*)`),
+	re(`-I([^@\-].*)`),
+	re(`-O`),
+	re(`-O([^@\-].*)`),
+	re(`-W`),
+	re(`-W([^@,]+)`), // -Wall but not -Wa,-foo.
+	re(`-f(no-)?objc-arc`),
+	re(`-f(no-)?omit-frame-pointer`),
+	re(`-f(no-)?(pic|PIC|pie|PIE)`),
+	re(`-f(no-)?split-stack`),
+	re(`-f(no-)?stack-(.+)`),
+	re(`-f(no-)?strict-aliasing`),
+	re(`-fsanitize=(.+)`),
+	re(`-g([^@\-].*)?`),
+	re(`-m(arch|cpu|fpu|tune)=([^@\-].*)`),
+	re(`-m(no-)?stack-(.+)`),
+	re(`-mmacosx-(.+)`),
+	re(`-mnop-fun-dllimport`),
+	re(`-pthread`),
+	re(`-std=([^@\-].*)`),
+	re(`-x([^@\-].*)`),
+}
+
+var validCompilerFlagsWithNextArg = []string{
+	"-D",
+	"-I",
+	"-framework",
+	"-x",
+}
+
+var validLinkerFlags = []*regexp.Regexp{
+	re(`-F([^@\-].*)`),
+	re(`-l([^@\-].*)`),
+	re(`-L([^@\-].*)`),
+	re(`-f(no-)?(pic|PIC|pie|PIE)`),
+	re(`-fsanitize=([^@\-].*)`),
+	re(`-g([^@\-].*)?`),
+	re(`-m(arch|cpu|fpu|tune)=([^@\-].*)`),
+	re(`-(pic|PIC|pie|PIE)`),
+	re(`-pthread`),
+
+	// Note that any wildcards in -Wl need to exclude comma,
+	// since -Wl splits its argument at commas and passes
+	// them all to the linker uninterpreted. Allowing comma
+	// in a wildcard would allow tunnelling arbitrary additional
+	// linker arguments through one of these.
+	re(`-Wl,-rpath,([^,@\-][^,]+)`),
+	re(`-Wl,--(no-)?warn-([^,]+)`),
+
+	re(`[a-zA-Z0-9_].*\.(o|obj|dll|dylib|so)`), // direct linker inputs: x.o or libfoo.so (but not -foo.o or @foo.o)
+}
+
+var validLinkerFlagsWithNextArg = []string{
+	"-F",
+	"-l",
+	"-L",
+	"-framework",
+}
+
+func checkCompilerFlags(name, source string, list []string) error {
+	return checkFlags(name, source, list, validCompilerFlags, validCompilerFlagsWithNextArg)
+}
+
+func checkLinkerFlags(name, source string, list []string) error {
+	return checkFlags(name, source, list, validLinkerFlags, validLinkerFlagsWithNextArg)
+}
+
+func checkFlags(name, source string, list []string, valid []*regexp.Regexp, validNext []string) error {
+	// Let users override rules with $CGO_CFLAGS_ALLOW, $CGO_CFLAGS_DISALLOW, etc.
+	var (
+		allow    *regexp.Regexp
+		disallow *regexp.Regexp
+	)
+	if env := os.Getenv("CGO_" + name + "_ALLOW"); env != "" {
+		r, err := regexp.Compile(env)
+		if err != nil {
+			return fmt.Errorf("parsing $CGO_%s_ALLOW: %v", name, err)
+		}
+		allow = r
+	}
+	if env := os.Getenv("CGO_" + name + "_DISALLOW"); env != "" {
+		r, err := regexp.Compile(env)
+		if err != nil {
+			return fmt.Errorf("parsing $CGO_%s_DISALLOW: %v", name, err)
+		}
+		disallow = r
+	}
+
+Args:
+	for i := 0; i < len(list); i++ {
+		arg := list[i]
+		if disallow != nil && disallow.FindString(arg) == arg {
+			goto Bad
+		}
+		if allow != nil && allow.FindString(arg) == arg {
+			continue Args
+		}
+		for _, re := range valid {
+			if re.FindString(arg) == arg { // must be complete match
+				continue Args
+			}
+		}
+		for _, x := range validNext {
+			if arg == x {
+				if i+1 < len(list) && SafeArg(list[i+1]) {
+					i++
+					continue Args
+				}
+				if i+1 < len(list) {
+					return fmt.Errorf("invalid flag in %s: %s %s", source, arg, list[i+1])
+				}
+				return fmt.Errorf("invalid flag in %s: %s without argument", source, arg)
+			}
+		}
+	Bad:
+		return fmt.Errorf("invalid flag in %s: %s", source, arg)
+	}
+	return nil
+}

src/cmd/go/security_test.go

@@ -0,0 +1,240 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"os"
+	"testing"
+)
+
+var goodCompilerFlags = [][]string{
+	{"-DFOO"},
+	{"-Dfoo=bar"},
+	{"-I/"},
+	{"-I/etc/passwd"},
+	{"-I."},
+	{"-O"},
+	{"-O2"},
+	{"-Osmall"},
+	{"-W"},
+	{"-Wall"},
+	{"-fobjc-arc"},
+	{"-fno-objc-arc"},
+	{"-fomit-frame-pointer"},
+	{"-fno-omit-frame-pointer"},
+	{"-fpic"},
+	{"-fno-pic"},
+	{"-fPIC"},
+	{"-fno-PIC"},
+	{"-fpie"},
+	{"-fno-pie"},
+	{"-fPIE"},
+	{"-fno-PIE"},
+	{"-fsplit-stack"},
+	{"-fno-split-stack"},
+	{"-fstack-xxx"},
+	{"-fno-stack-xxx"},
+	{"-fsanitize=hands"},
+	{"-g"},
+	{"-ggdb"},
+	{"-march=souza"},
+	{"-mcpu=123"},
+	{"-mfpu=123"},
+	{"-mtune=happybirthday"},
+	{"-mstack-overflow"},
+	{"-mno-stack-overflow"},
+	{"-mmacosx-version"},
+	{"-mnop-fun-dllimport"},
+	{"-pthread"},
+	{"-std=c99"},
+	{"-xc"},
+	{"-D", "FOO"},
+	{"-D", "foo=bar"},
+	{"-I", "."},
+	{"-I", "/etc/passwd"},
+	{"-I", "世界"},
+	{"-framework", "Chocolate"},
+	{"-x", "c"},
+}
+
+var badCompilerFlags = [][]string{
+	{"-D@X"},
+	{"-D-X"},
+	{"-I@dir"},
+	{"-I-dir"},
+	{"-O@1"},
+	{"-Wa,-foo"},
+	{"-W@foo"},
+	{"-g@gdb"},
+	{"-g-gdb"},
+	{"-march=@dawn"},
+	{"-march=-dawn"},
+	{"-std=@c99"},
+	{"-std=-c99"},
+	{"-x@c"},
+	{"-x-c"},
+	{"-D", "@foo"},
+	{"-D", "-foo"},
+	{"-I", "@foo"},
+	{"-I", "-foo"},
+	{"-framework", "-Caffeine"},
+	{"-framework", "@Home"},
+	{"-x", "--c"},
+	{"-x", "@obj"},
+}
+
+func TestCheckCompilerFlags(t *testing.T) {
+	for _, f := range goodCompilerFlags {
+		if err := checkCompilerFlags("test", "test", f); err != nil {
+			t.Errorf("unexpected error for %q: %v", f, err)
+		}
+	}
+	for _, f := range badCompilerFlags {
+		if err := checkCompilerFlags("test", "test", f); err == nil {
+			t.Errorf("missing error for %q", f)
+		}
+	}
+}
+
+var goodLinkerFlags = [][]string{
+	{"-Fbar"},
+	{"-lbar"},
+	{"-Lbar"},
+	{"-fpic"},
+	{"-fno-pic"},
+	{"-fPIC"},
+	{"-fno-PIC"},
+	{"-fpie"},
+	{"-fno-pie"},
+	{"-fPIE"},
+	{"-fno-PIE"},
+	{"-fsanitize=hands"},
+	{"-g"},
+	{"-ggdb"},
+	{"-march=souza"},
+	{"-mcpu=123"},
+	{"-mfpu=123"},
+	{"-mtune=happybirthday"},
+	{"-pic"},
+	{"-pthread"},
+	{"-Wl,-rpath,foo"},
+	{"-Wl,-rpath,$ORIGIN/foo"},
+	{"-Wl,--warn-error"},
+	{"-Wl,--no-warn-error"},
+	{"foo.so"},
+	{"_世界.dll"},
+	{"libcgosotest.dylib"},
+	{"-F", "framework"},
+	{"-l", "."},
+	{"-l", "/etc/passwd"},
+	{"-l", "世界"},
+	{"-L", "framework"},
+	{"-framework", "Chocolate"},
+}
+
+var badLinkerFlags = [][]string{
+	{"-DFOO"},
+	{"-Dfoo=bar"},
+	{"-O"},
+	{"-O2"},
+	{"-Osmall"},
+	{"-W"},
+	{"-Wall"},
+	{"-fobjc-arc"},
+	{"-fno-objc-arc"},
+	{"-fomit-frame-pointer"},
+	{"-fno-omit-frame-pointer"},
+	{"-fsplit-stack"},
+	{"-fno-split-stack"},
+	{"-fstack-xxx"},
+	{"-fno-stack-xxx"},
+	{"-mstack-overflow"},
+	{"-mno-stack-overflow"},
+	{"-mmacosx-version"},
+	{"-mnop-fun-dllimport"},
+	{"-std=c99"},
+	{"-xc"},
+	{"-D", "FOO"},
+	{"-D", "foo=bar"},
+	{"-I", "FOO"},
+	{"-L", "@foo"},
+	{"-L", "-foo"},
+	{"-x", "c"},
+	{"-D@X"},
+	{"-D-X"},
+	{"-I@dir"},
+	{"-I-dir"},
+	{"-O@1"},
+	{"-Wa,-foo"},
+	{"-W@foo"},
+	{"-g@gdb"},
+	{"-g-gdb"},
+	{"-march=@dawn"},
+	{"-march=-dawn"},
+	{"-std=@c99"},
+	{"-std=-c99"},
+	{"-x@c"},
+	{"-x-c"},
+	{"-D", "@foo"},
+	{"-D", "-foo"},
+	{"-I", "@foo"},
+	{"-I", "-foo"},
+	{"-l", "@foo"},
+	{"-l", "-foo"},
+	{"-framework", "-Caffeine"},
+	{"-framework", "@Home"},
+	{"-x", "--c"},
+	{"-x", "@obj"},
+	{"-Wl,-rpath,@foo"},
+}
+
+func TestCheckLinkerFlags(t *testing.T) {
+	for _, f := range goodLinkerFlags {
+		if err := checkLinkerFlags("test", "test", f); err != nil {
+			t.Errorf("unexpected error for %q: %v", f, err)
+		}
+	}
+	for _, f := range badLinkerFlags {
+		if err := checkLinkerFlags("test", "test", f); err == nil {
+			t.Errorf("missing error for %q", f)
+		}
+	}
+}
+
+func TestCheckFlagAllowDisallow(t *testing.T) {
+	if err := checkCompilerFlags("TEST", "test", []string{"-disallow"}); err == nil {
+		t.Fatalf("missing error for -disallow")
+	}
+	os.Setenv("CGO_TEST_ALLOW", "-disallo")
+	if err := checkCompilerFlags("TEST", "test", []string{"-disallow"}); err == nil {
+		t.Fatalf("missing error for -disallow with CGO_TEST_ALLOW=-disallo")
+	}
+	os.Setenv("CGO_TEST_ALLOW", "-disallow")
+	if err := checkCompilerFlags("TEST", "test", []string{"-disallow"}); err != nil {
+		t.Fatalf("unexpected error for -disallow with CGO_TEST_ALLOW=-disallow: %v", err)
+	}
+	os.Unsetenv("CGO_TEST_ALLOW")
+
+	if err := checkCompilerFlags("TEST", "test", []string{"-Wall"}); err != nil {
+		t.Fatalf("unexpected error for -Wall: %v", err)
+	}
+	os.Setenv("CGO_TEST_DISALLOW", "-Wall")
+	if err := checkCompilerFlags("TEST", "test", []string{"-Wall"}); err == nil {
+		t.Fatalf("missing error for -Wall with CGO_TEST_DISALLOW=-Wall")
+	}
+	os.Setenv("CGO_TEST_ALLOW", "-Wall") // disallow wins
+	if err := checkCompilerFlags("TEST", "test", []string{"-Wall"}); err == nil {
+		t.Fatalf("missing error for -Wall with CGO_TEST_DISALLOW=-Wall and CGO_TEST_ALLOW=-Wall")
+	}
+
+	os.Setenv("CGO_TEST_ALLOW", "-fplugin.*")
+	os.Setenv("CGO_TEST_DISALLOW", "-fplugin=lint.so")
+	if err := checkCompilerFlags("TEST", "test", []string{"-fplugin=faster.so"}); err != nil {
+		t.Fatalf("unexpected error for -fplugin=faster.so: %v", err)
+	}
+	if err := checkCompilerFlags("TEST", "test", []string{"-fplugin=lint.so"}); err == nil {
+		t.Fatalf("missing error for -fplugin=lint.so: %v", err)
+	}
+}

src/cmd/go/vcs.go

@@ -497,11 +497,28 @@ func vcsFromDir(dir, srcRoot string) (vcs *vcsCmd, root string, err error) {
 		return nil, "", fmt.Errorf("directory %q is outside source root %q", dir, srcRoot)
 	}
 
+	var vcsRet *vcsCmd
+	var rootRet string
+
 	origDir := dir
 	for len(dir) > len(srcRoot) {
 		for _, vcs := range vcsList {
 			if _, err := os.Stat(filepath.Join(dir, "."+vcs.cmd)); err == nil {
-				return vcs, filepath.ToSlash(dir[len(srcRoot)+1:]), nil
+				root := filepath.ToSlash(dir[len(srcRoot)+1:])
+				// Record first VCS we find, but keep looking,
+				// to detect mistakes like one kind of VCS inside another.
+				if vcsRet == nil {
+					vcsRet = vcs
+					rootRet = root
+					continue
+				}
+				// Allow .git inside .git, which can arise due to submodules.
+				if vcsRet == vcs && vcs.cmd == "git" {
+					continue
+				}
+				// Otherwise, we have one VCS inside a different VCS.
+				return nil, "", fmt.Errorf("directory %q uses %s, but parent %q uses %s",
+					filepath.Join(srcRoot, rootRet), vcsRet.cmd, filepath.Join(srcRoot, root), vcs.cmd)
 			}
 		}
 
@@ -514,9 +531,48 @@ func vcsFromDir(dir, srcRoot string) (vcs *vcsCmd, root string, err error) {
 		dir = ndir
 	}
 
+	if vcsRet != nil {
+		return vcsRet, rootRet, nil
+	}
+
 	return nil, "", fmt.Errorf("directory %q is not using a known version control system", origDir)
 }
 
+// checkNestedVCS checks for an incorrectly-nested VCS-inside-VCS
+// situation for dir, checking parents up until srcRoot.
+func checkNestedVCS(vcs *vcsCmd, dir, srcRoot string) error {
+	if len(dir) <= len(srcRoot) || dir[len(srcRoot)] != filepath.Separator {
+		return fmt.Errorf("directory %q is outside source root %q", dir, srcRoot)
+	}
+
+	otherDir := dir
+	for len(otherDir) > len(srcRoot) {
+		for _, otherVCS := range vcsList {
+			if _, err := os.Stat(filepath.Join(otherDir, "."+otherVCS.cmd)); err == nil {
+				// Allow expected vcs in original dir.
+				if otherDir == dir && otherVCS == vcs {
+					continue
+				}
+				// Allow .git inside .git, which can arise due to submodules.
+				if otherVCS == vcs && vcs.cmd == "git" {
+					continue
+				}
+				// Otherwise, we have one VCS inside a different VCS.
+				return fmt.Errorf("directory %q uses %s, but parent %q uses %s", dir, vcs.cmd, otherDir, otherVCS.cmd)
+			}
+		}
+		// Move to parent.
+		newDir := filepath.Dir(otherDir)
+		if len(newDir) >= len(otherDir) {
+			// Shouldn't happen, but just in case, stop.
+			break
+		}
+		otherDir = newDir
+	}
+
+	return nil
+}
+
 // repoRoot represents a version control system, a repo, and a root of
 // where to put it on disk.
 type repoRoot struct {

src/cmd/gofmt/testdata/typealias.golden

@@ -1,24 +0,0 @@
-package q
-
-import "p"
-
-type _ = int
-type a = struct{ x int }
-type b = p.B
-
-type (
-	_  = chan<- int
-	aa = interface{}
-	bb = p.BB
-)
-
-// TODO(gri) We may want to put the '=' into a separate column if
-// we have mixed (regular and alias) type declarations in a group.
-type (
-	_   chan<- int
-	_   = chan<- int
-	aa0 interface{}
-	aaa = interface{}
-	bb0 p.BB
-	bbb = p.BB
-)

src/cmd/gofmt/testdata/typealias.input

@@ -1,24 +0,0 @@
-package q
-
-import "p"
-
-type _ = int
-type a = struct{ x int }
-type b = p.B
-
-type (
-	_ = chan<- int
-	aa = interface{}
-	bb = p.BB
-)
-
-// TODO(gri) We may want to put the '=' into a separate column if
-// we have mixed (regular and alias) type declarations in a group.
-type (
-	_ chan<- int
-	_ = chan<- int
-	aa0 interface{}
-	aaa = interface{}
-	bb0 p.BB
-	bbb = p.BB
-)

src/cmd/internal/obj/x86/obj6.go

@@ -322,15 +322,13 @@ func progedit(ctxt *obj.Link, p *obj.Prog) {
 
 // Rewrite p, if necessary, to access global data via the global offset table.
 func rewriteToUseGot(ctxt *obj.Link, p *obj.Prog) {
-	var add, lea, mov obj.As
+	var lea, mov obj.As
 	var reg int16
 	if p.Mode == 64 {
-		add = AADDQ
 		lea = ALEAQ
 		mov = AMOVQ
 		reg = REG_R15
 	} else {
-		add = AADDL
 		lea = ALEAL
 		mov = AMOVL
 		reg = REG_CX
@@ -347,8 +345,10 @@ func rewriteToUseGot(ctxt *obj.Link, p *obj.Prog) {
 		//     ADUFFxxx $offset
 		// becomes
 		//     $MOV runtime.duffxxx@GOT, $reg
-		//     $ADD $offset, $reg
+		//     $LEA $offset($reg), $reg
 		//     CALL $reg
+		// (we use LEAx rather than ADDx because ADDx clobbers
+		// flags and duffzero on 386 does not otherwise do so)
 		var sym *obj.LSym
 		if p.As == obj.ADUFFZERO {
 			sym = obj.Linklookup(ctxt, "runtime.duffzero", 0)
@@ -365,9 +365,10 @@ func rewriteToUseGot(ctxt *obj.Link, p *obj.Prog) {
 		p.To.Offset = 0
 		p.To.Sym = nil
 		p1 := obj.Appendp(ctxt, p)
-		p1.As = add
-		p1.From.Type = obj.TYPE_CONST
+		p1.As = lea
+		p1.From.Type = obj.TYPE_MEM
 		p1.From.Offset = offset
+		p1.From.Reg = reg
 		p1.To.Type = obj.TYPE_REG
 		p1.To.Reg = reg
 		p2 := obj.Appendp(ctxt, p1)

src/cmd/link/internal/ld/data.go

@@ -324,18 +324,36 @@ func isRuntimeDepPkg(pkg string) bool {
 	return strings.HasPrefix(pkg, "runtime/internal/") && !strings.HasSuffix(pkg, "_test")
 }
 
+// Estimate the max size needed to hold any new trampolines created for this function. This
+// is used to determine when the section can be split if it becomes too large, to ensure that
+// the trampolines are in the same section as the function that uses them.
+func maxSizeTrampolinesPPC64(s *Symbol, isTramp bool) uint64 {
+	// If Thearch.Trampoline is nil, then trampoline support is not available on this arch.
+	// A trampoline does not need any dependent trampolines.
+	if Thearch.Trampoline == nil || isTramp {
+		return 0
+	}
+
+	n := uint64(0)
+	for ri := range s.R {
+		r := &s.R[ri]
+		if r.Type.IsDirectJump() {
+			n++
+		}
+	}
+	// Trampolines in ppc64 are 4 instructions.
+	return n * 16
+}
+
 // detect too-far jumps in function s, and add trampolines if necessary
-// ARM supports trampoline insertion for internal and external linking
-// PPC64 & PPC64LE support trampoline insertion for internal linking only
+// ARM, PPC64 & PPC64LE support trampoline insertion for internal and external linking
+// On PPC64 & PPC64LE the text sections might be split but will still insert trampolines
+// where necessary.
 func trampoline(ctxt *Link, s *Symbol) {
 	if Thearch.Trampoline == nil {
 		return // no need or no support of trampolines on this arch
 	}
 
-	if Linkmode == LinkExternal && SysArch.Family == sys.PPC64 {
-		return
-	}
-
 	for ri := range s.R {
 		r := &s.R[ri]
 		if !r.Type.IsDirectJump() {
@@ -2044,14 +2062,14 @@ func (ctxt *Link) textaddress() {
 	sect.Vaddr = va
 	ntramps := 0
 	for _, sym := range ctxt.Textp {
-		sect, n, va = assignAddress(ctxt, sect, n, sym, va)
+		sect, n, va = assignAddress(ctxt, sect, n, sym, va, false)
 
 		trampoline(ctxt, sym) // resolve jumps, may add trampolines if jump too far
 
 		// lay down trampolines after each function
 		for ; ntramps < len(ctxt.tramps); ntramps++ {
 			tramp := ctxt.tramps[ntramps]
-			sect, n, va = assignAddress(ctxt, sect, n, tramp, va)
+			sect, n, va = assignAddress(ctxt, sect, n, tramp, va, true)
 		}
 	}
 
@@ -2077,7 +2095,7 @@ func (ctxt *Link) textaddress() {
 // assigns address for a text symbol, returns (possibly new) section, its number, and the address
 // Note: once we have trampoline insertion support for external linking, this function
 // will not need to create new text sections, and so no need to return sect and n.
-func assignAddress(ctxt *Link, sect *Section, n int, sym *Symbol, va uint64) (*Section, int, uint64) {
+func assignAddress(ctxt *Link, sect *Section, n int, sym *Symbol, va uint64, isTramp bool) (*Section, int, uint64) {
 	sym.Sect = sect
 	if sym.Type&obj.SSUB != 0 {
 		return sect, n, va
@@ -2106,7 +2124,7 @@ func assignAddress(ctxt *Link, sect *Section, n int, sym *Symbol, va uint64) (*S
 
 	// Only break at outermost syms.
 
-	if SysArch.InFamily(sys.PPC64) && sym.Outer == nil && Iself && Linkmode == LinkExternal && va-sect.Vaddr+funcsize > 0x1c00000 {
+	if SysArch.InFamily(sys.PPC64) && sym.Outer == nil && Iself && Linkmode == LinkExternal && va-sect.Vaddr+funcsize+maxSizeTrampolinesPPC64(sym, isTramp) > 0x1c00000 {
 
 		// Set the length for the previous text section
 		sect.Length = va - sect.Vaddr

src/cmd/link/internal/ld/decodesym.go

@@ -255,7 +255,7 @@ func decodetypeStructFieldType(s *Symbol, i int) *Symbol {
 
 func decodetypeStructFieldOffs(arch *sys.Arch, s *Symbol, i int) int64 {
 	off := decodetypeStructFieldArrayOff(s, i)
-	return int64(decodeInuxi(arch, s.P[off+2*SysArch.PtrSize:], SysArch.IntSize) >> 1)
+	return int64(decodeInuxi(arch, s.P[off+2*SysArch.PtrSize:], SysArch.IntSize))
 }
 
 // InterfaceType.methods.length

src/cmd/link/internal/ppc64/asm.go

@@ -522,13 +522,22 @@ func archrelocaddr(ctxt *ld.Link, r *ld.Reloc, s *ld.Symbol, val *int64) int {
 // resolve direct jump relocation r in s, and add trampoline if necessary
 func trampoline(ctxt *ld.Link, r *ld.Reloc, s *ld.Symbol) {
 
+	// Trampolines are created if the branch offset is too large and the linker cannot insert a call stub to handle it.
+	// For internal linking, trampolines are always created for long calls.
+	// For external linking, the linker can insert a call stub to handle a long call, but depends on having the TOC address in
+	// r2.  For those build modes with external linking where the TOC address is not maintained in r2, trampolines must be created.
+	if ld.Linkmode == ld.LinkExternal && (ctxt.DynlinkingGo() || ld.Buildmode == ld.BuildmodeCArchive || ld.Buildmode == ld.BuildmodeCShared || ld.Buildmode == ld.BuildmodePIE) {
+		// No trampolines needed since r2 contains the TOC
+		return
+	}
+
 	t := ld.Symaddr(r.Sym) + r.Add - (s.Value + int64(r.Off))
 	switch r.Type {
 	case obj.R_CALLPOWER:
 
 		// If branch offset is too far then create a trampoline.
 
-		if int64(int32(t<<6)>>6) != t || (*ld.FlagDebugTramp > 1 && s.File != r.Sym.File) {
+		if (ld.Linkmode == ld.LinkExternal && s.Sect != r.Sym.Sect) || (ld.Linkmode == ld.LinkInternal && int64(int32(t<<6)>>6) != t) || (*ld.FlagDebugTramp > 1 && s.File != r.Sym.File) {
 			var tramp *ld.Symbol
 			for i := 0; ; i++ {
 
@@ -552,26 +561,20 @@ func trampoline(ctxt *ld.Link, r *ld.Reloc, s *ld.Symbol) {
 
 				t = ld.Symaddr(tramp) + r.Add - (s.Value + int64(r.Off))
 
-				// If the offset of the trampoline that has been found is within range, use it.
-				if int64(int32(t<<6)>>6) == t {
+				// With internal linking, the trampoline can be used if it is not too far.
+				// With external linking, the trampoline must be in this section for it to be reused.
+				if (ld.Linkmode == ld.LinkInternal && int64(int32(t<<6)>>6) == t) || (ld.Linkmode == ld.LinkExternal && s.Sect == tramp.Sect) {
 					break
 				}
 			}
 			if tramp.Type == 0 {
-				ctxt.AddTramp(tramp)
-				tramp.Size = 16 // 4 instructions
-				tramp.P = make([]byte, tramp.Size)
-				t = ld.Symaddr(r.Sym) + r.Add
-				f := t & 0xffff0000
-				o1 := uint32(0x3fe00000 | (f >> 16)) // lis r31,trampaddr hi (r31 is temp reg)
-				f = t & 0xffff
-				o2 := uint32(0x63ff0000 | f) // ori r31,trampaddr lo
-				o3 := uint32(0x7fe903a6)     // mtctr
-				o4 := uint32(0x4e800420)     // bctr
-				ld.SysArch.ByteOrder.PutUint32(tramp.P, o1)
-				ld.SysArch.ByteOrder.PutUint32(tramp.P[4:], o2)
-				ld.SysArch.ByteOrder.PutUint32(tramp.P[8:], o3)
-				ld.SysArch.ByteOrder.PutUint32(tramp.P[12:], o4)
+				if ctxt.DynlinkingGo() || ld.Buildmode == ld.BuildmodeCArchive || ld.Buildmode == ld.BuildmodeCShared || ld.Buildmode == ld.BuildmodePIE {
+					// Should have returned for above cases
+					ld.Errorf(s, "unexpected trampoline for shared or dynamic linking\n")
+				} else {
+					ctxt.AddTramp(tramp)
+					gentramp(tramp, r.Sym, int64(r.Add))
+				}
 			}
 			r.Sym = tramp
 			r.Add = 0 // This was folded into the trampoline target address
@@ -582,6 +585,42 @@ func trampoline(ctxt *ld.Link, r *ld.Reloc, s *ld.Symbol) {
 	}
 }
 
+func gentramp(tramp, target *ld.Symbol, offset int64) {
+	// Used for default build mode for an executable
+	// Address of the call target is generated using
+	// relocation and doesn't depend on r2 (TOC).
+	tramp.Size = 16 // 4 instructions
+	tramp.P = make([]byte, tramp.Size)
+	t := ld.Symaddr(target) + offset
+	o1 := uint32(0x3fe00000) // lis r31,targetaddr hi
+	o2 := uint32(0x3bff0000) // addi r31,targetaddr lo
+	// With external linking, the target address must be
+	// relocated using LO and HA
+	if ld.Linkmode == ld.LinkExternal {
+		tr := ld.Addrel(tramp)
+		tr.Off = 0
+		tr.Type = obj.R_ADDRPOWER
+		tr.Siz = 8 // generates 2 relocations:  HA + LO
+		tr.Sym = target
+		tr.Add = offset
+	} else {
+		// adjustment needed if lo has sign bit set
+		// when using addi to compute address
+		val := uint32((t & 0xffff0000) >> 16)
+		if t&0x8000 != 0 {
+			val += 1
+		}
+		o1 |= val                // hi part of addr
+		o2 |= uint32(t & 0xffff) // lo part of addr
+	}
+	o3 := uint32(0x7fe903a6) // mtctr r31
+	o4 := uint32(0x4e800420) // bctr
+	ld.SysArch.ByteOrder.PutUint32(tramp.P, o1)
+	ld.SysArch.ByteOrder.PutUint32(tramp.P[4:], o2)
+	ld.SysArch.ByteOrder.PutUint32(tramp.P[8:], o3)
+	ld.SysArch.ByteOrder.PutUint32(tramp.P[12:], o4)
+}
+
 func archreloc(ctxt *ld.Link, r *ld.Reloc, s *ld.Symbol, val *int64) int {
 	if ld.Linkmode == ld.LinkExternal {
 		switch r.Type {

src/crypto/x509/verify.go

@@ -191,6 +191,10 @@ func matchNameConstraint(domain, constraint string) bool {
 
 // isValid performs validity checks on the c.
 func (c *Certificate) isValid(certType int, currentChain []*Certificate, opts *VerifyOptions) error {
+	if len(c.UnhandledCriticalExtensions) > 0 {
+		return UnhandledCriticalExtension{}
+	}
+
 	if len(currentChain) > 0 {
 		child := currentChain[len(currentChain)-1]
 		if !bytes.Equal(child.RawIssuer, c.RawSubject) {
@@ -279,10 +283,6 @@ func (c *Certificate) Verify(opts VerifyOptions) (chains [][]*Certificate, err e
 		return c.systemVerify(&opts)
 	}
 
-	if len(c.UnhandledCriticalExtensions) > 0 {
-		return nil, UnhandledCriticalExtension{}
-	}
-
 	if opts.Roots == nil {
 		opts.Roots = systemRootsPool()
 		if opts.Roots == nil {

src/crypto/x509/verify_test.go

@@ -263,6 +263,30 @@ var verifyTests = []verifyTest{
 
 		errorCallback: expectSubjectIssuerMismatcthError,
 	},
+	{
+		// Test that unknown critical extensions in a leaf cause a
+		// verify error.
+		leaf:          criticalExtLeafWithExt,
+		dnsName:       "example.com",
+		intermediates: []string{criticalExtIntermediate},
+		roots:         []string{criticalExtRoot},
+		currentTime:   1486684488,
+		systemSkip:    true,
+
+		errorCallback: expectUnhandledCriticalExtension,
+	},
+	{
+		// Test that unknown critical extensions in an intermediate
+		// cause a verify error.
+		leaf:          criticalExtLeaf,
+		dnsName:       "example.com",
+		intermediates: []string{criticalExtIntermediateWithExt},
+		roots:         []string{criticalExtRoot},
+		currentTime:   1486684488,
+		systemSkip:    true,
+
+		errorCallback: expectUnhandledCriticalExtension,
+	},
 }
 
 func expectHostnameError(t *testing.T, i int, err error) (ok bool) {
@@ -330,6 +354,14 @@ func expectSubjectIssuerMismatcthError(t *testing.T, i int, err error) (ok bool)
 	return true
 }
 
+func expectUnhandledCriticalExtension(t *testing.T, i int, err error) (ok bool) {
+	if _, ok := err.(UnhandledCriticalExtension); !ok {
+		t.Errorf("#%d: error was not an UnhandledCriticalExtension: %s", i, err)
+		return false
+	}
+	return true
+}
+
 func certificateFromPEM(pemBytes string) (*Certificate, error) {
 	block, _ := pem.Decode([]byte(pemBytes))
 	if block == nil {
@@ -1379,3 +1411,67 @@ w67CoNRb81dy+4Q1lGpA8ORoLWh5fIq2t2eNGc4qB8vlTIKiESzAwu7u3sRfuWQi
 4R+gnfLd37FWflMHwztFbVTuNtPOljCX0LN7KcuoXYlr05RhQrmoN7fQHsrZMNLs
 8FVjHdKKu+uPstwd04Uy4BR/H2y1yerN9j/L6ZkMl98iiA==
 -----END CERTIFICATE-----`
+
+const criticalExtRoot = `-----BEGIN CERTIFICATE-----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=
+-----END CERTIFICATE-----`
+
+const criticalExtIntermediate = `-----BEGIN CERTIFICATE-----
+MIIBszCCAVmgAwIBAgIJAL2kcGZKpzVqMAoGCCqGSM49BAMCMB0xDDAKBgNVBAoT
+A09yZzENMAsGA1UEAxMEUm9vdDAeFw0xNTAxMDEwMDAwMDBaFw0yNTAxMDEwMDAw
+MDBaMCUxDDAKBgNVBAoTA09yZzEVMBMGA1UEAxMMSW50ZXJtZWRpYXRlMFkwEwYH
+KoZIzj0CAQYIKoZIzj0DAQcDQgAESqVq92iPEq01cL4o99WiXDc5GZjpjNlzMS1n
+rk8oHcVDp4tQRRQG3F4A6dF1rn/L923ha3b0fhDLlAvXZB+7EKN6MHgwDgYDVR0P
+AQH/BAQDAgIEMB0GA1UdJQQWMBQGCCsGAQUFBwMBBggrBgEFBQcDAjAPBgNVHRMB
+Af8EBTADAQH/MBkGA1UdDgQSBBCMGmiotXbbXVd7H40UsgajMBsGA1UdIwQUMBKA
+EEA31wH7QC+4HH5UBCeMWQEwCgYIKoZIzj0EAwIDSAAwRQIhAOhhNRb6KV7h3wbE
+cdap8bojzvUcPD78fbsQPCNw1jPxAiBOeAJhlTwpKn9KHpeJphYSzydj9NqcS26Y
+xXbdbm27KQ==
+-----END CERTIFICATE-----`
+
+const criticalExtLeafWithExt = `-----BEGIN CERTIFICATE-----
+MIIBxTCCAWugAwIBAgIJAJZAUtw5ccb1MAoGCCqGSM49BAMCMCUxDDAKBgNVBAoT
+A09yZzEVMBMGA1UEAxMMSW50ZXJtZWRpYXRlMB4XDTE1MDEwMTAwMDAwMFoXDTI1
+MDEwMTAwMDAwMFowJDEMMAoGA1UEChMDT3JnMRQwEgYDVQQDEwtleGFtcGxlLmNv
+bTBZMBMGByqGSM49AgEGCCqGSM49AwEHA0IABF3ABa2+B6gUyg6ayCaRQWYY/+No
+6PceLqEavZNUeVNuz7bS74Toy8I7R3bGMkMgbKpLSPlPTroAATvebTXoBaijgYQw
+gYEwDgYDVR0PAQH/BAQDAgWgMB0GA1UdJQQWMBQGCCsGAQUFBwMBBggrBgEFBQcD
+AjAMBgNVHRMBAf8EAjAAMBkGA1UdDgQSBBBRNtBL2vq8nCV3qVp7ycxMMBsGA1Ud
+IwQUMBKAEIwaaKi1dttdV3sfjRSyBqMwCgYDUQMEAQH/BAAwCgYIKoZIzj0EAwID
+SAAwRQIgVjy8GBgZFiagexEuDLqtGjIRJQtBcf7lYgf6XFPH1h4CIQCT6nHhGo6E
+I+crEm4P5q72AnA/Iy0m24l7OvLuXObAmg==
+-----END CERTIFICATE-----`
+
+const criticalExtIntermediateWithExt = `-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----`
+
+const criticalExtLeaf = `-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----`

src/crypto/x509/x509_test.go

@@ -518,74 +518,6 @@ func TestCreateSelfSignedCertificate(t *testing.T) {
 	}
 }
 
-func TestUnknownCriticalExtension(t *testing.T) {
-	priv, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
-	if err != nil {
-		t.Fatalf("Failed to generate ECDSA key: %s", err)
-	}
-
-	oids := []asn1.ObjectIdentifier{
-		// This OID is in the PKIX arc, but unknown.
-		{2, 5, 29, 999999},
-		// This is a nonsense, unassigned OID.
-		{1, 2, 3, 4},
-	}
-
-	for _, oid := range oids {
-		template := Certificate{
-			SerialNumber: big.NewInt(1),
-			Subject: pkix.Name{
-				CommonName: "foo",
-			},
-			NotBefore: time.Unix(1000, 0),
-			NotAfter:  time.Now().AddDate(1, 0, 0),
-
-			BasicConstraintsValid: true,
-			IsCA: true,
-
-			KeyUsage:    KeyUsageCertSign,
-			ExtKeyUsage: []ExtKeyUsage{ExtKeyUsageServerAuth},
-
-			ExtraExtensions: []pkix.Extension{
-				{
-					Id:       oid,
-					Critical: true,
-					Value:    nil,
-				},
-			},
-		}
-
-		derBytes, err := CreateCertificate(rand.Reader, &template, &template, &priv.PublicKey, priv)
-		if err != nil {
-			t.Fatalf("failed to create certificate: %s", err)
-		}
-
-		cert, err := ParseCertificate(derBytes)
-		if err != nil {
-			t.Fatalf("Certificate with unknown critical extension was not parsed: %s", err)
-		}
-
-		roots := NewCertPool()
-		roots.AddCert(cert)
-
-		// Setting Roots ensures that Verify won't delegate to the OS
-		// library and thus the correct error should always be
-		// returned.
-		_, err = cert.Verify(VerifyOptions{Roots: roots})
-		if err == nil {
-			t.Fatal("Certificate with unknown critical extension was verified without error")
-		}
-		if _, ok := err.(UnhandledCriticalExtension); !ok {
-			t.Fatalf("Error was %#v, but wanted one of type UnhandledCriticalExtension", err)
-		}
-
-		cert.UnhandledCriticalExtensions = nil
-		if _, err = cert.Verify(VerifyOptions{Roots: roots}); err != nil {
-			t.Errorf("Certificate failed to verify after unhandled critical extensions were cleared: %s", err)
-		}
-	}
-}
-
 // Self-signed certificate using ECDSA with SHA1 & secp256r1
 var ecdsaSHA1CertPem = `
 -----BEGIN CERTIFICATE-----

src/go/ast/ast.go

@@ -848,7 +848,6 @@ type (
 	TypeSpec struct {
 		Doc     *CommentGroup // associated documentation; or nil
 		Name    *Ident        // type name
-		Assign  token.Pos     // position of '=', if any
 		Type    Expr          // *Ident, *ParenExpr, *SelectorExpr, *StarExpr, or any of the *XxxTypes
 		Comment *CommentGroup // line comments; or nil
 	}

src/go/build/build.go

@@ -290,8 +290,7 @@ func defaultContext() Context {
 	// in all releases >= Go 1.x. Code that requires Go 1.x or later should
 	// say "+build go1.x", and code that should only be built before Go 1.x
 	// (perhaps it is the stub to use in that case) should say "+build !go1.x".
-	// NOTE: If you add to this list, also update the doc comment in doc.go.
-	c.ReleaseTags = []string{"go1.1", "go1.2", "go1.3", "go1.4", "go1.5", "go1.6", "go1.7", "go1.8", "go1.8.typealias"}
+	c.ReleaseTags = []string{"go1.1", "go1.2", "go1.3", "go1.4", "go1.5", "go1.6", "go1.7", "go1.8"}
 
 	env := os.Getenv("CGO_ENABLED")
 	if env == "" {

src/go/build/doc.go

@@ -105,7 +105,6 @@
 //	- "go1.6", from Go version 1.6 onward
 //	- "go1.7", from Go version 1.7 onward
 //	- "go1.8", from Go version 1.8 onward
-//	- "go1.8.typealias", for Go version 1.8 with aliases
 //	- any additional words listed in ctxt.BuildTags
 //
 // If a file's name, after stripping the extension and a possible _test suffix,

src/go/internal/gccgoimporter/importer_test.go

@@ -101,7 +101,6 @@ var importerTests = [...]importerTest{
 	{pkgpath: "unicode", name: "IsUpper", want: "func IsUpper(r rune) bool"},
 	{pkgpath: "unicode", name: "MaxRune", want: "const MaxRune untyped rune", wantval: "1114111"},
 	{pkgpath: "imports", wantinits: []string{"imports..import", "fmt..import", "math..import"}},
-	{pkgpath: "alias", name: "IntAlias2", want: "type IntAlias2 = Int"},
 }
 
 func TestGoxImporter(t *testing.T) {

src/go/internal/gccgoimporter/parser.go

@@ -370,41 +370,27 @@ func (p *parser) parseConst(pkg *types.Package) *types.Const {
 	return types.NewConst(token.NoPos, pkg, name, typ, val)
 }
 
-// NamedType = TypeName [ "=" ] Type { Method } .
-// TypeName  = ExportedName .
-// Method    = "func" "(" Param ")" Name ParamList ResultList ";" .
-func (p *parser) parseNamedType(n int) types.Type {
+// TypeName = ExportedName .
+func (p *parser) parseTypeName() *types.TypeName {
 	pkg, name := p.parseExportedName()
 	scope := pkg.Scope()
-
-	if p.tok == '=' {
-		// type alias
-		p.next()
-		typ := p.parseType(pkg)
-		if obj := scope.Lookup(name); obj != nil {
-			typ = obj.Type() // use previously imported type
-			if typ == nil {
-				p.errorf("%v (type alias) used in cycle", obj)
-			}
-		} else {
-			obj = types.NewTypeName(token.NoPos, pkg, name, typ)
-			scope.Insert(obj)
-		}
-		p.typeMap[n] = typ
-		return typ
+	if obj := scope.Lookup(name); obj != nil {
+		return obj.(*types.TypeName)
 	}
+	obj := types.NewTypeName(token.NoPos, pkg, name, nil)
+	// a named type may be referred to before the underlying type
+	// is known - set it up
+	types.NewNamed(obj, nil, nil)
+	scope.Insert(obj)
+	return obj
+}
 
-	// named type
-	obj := scope.Lookup(name)
-	if obj == nil {
-		// a named type may be referred to before the underlying type
-		// is known - set it up
-		tname := types.NewTypeName(token.NoPos, pkg, name, nil)
-		types.NewNamed(tname, nil, nil)
-		scope.Insert(tname)
-		obj = tname
-	}
+// NamedType = TypeName Type { Method } .
+// Method    = "func" "(" Param ")" Name ParamList ResultList ";" .
+func (p *parser) parseNamedType(n int) types.Type {
+	obj := p.parseTypeName()
 
+	pkg := obj.Pkg()
 	typ := obj.Type()
 	p.typeMap[n] = typ
 
@@ -423,8 +409,8 @@ func (p *parser) parseNamedType(n int) types.Type {
 		nt.SetUnderlying(underlying.Underlying())
 	}
 
-	// collect associated methods
 	for p.tok == scanner.Ident {
+		// collect associated methods
 		p.expectKeyword("func")
 		p.expect('(')
 		receiver, _ := p.parseParam(pkg)

src/go/internal/gccgoimporter/testdata/alias.gox

@@ -1,4 +0,0 @@
-v1;
-package alias;
-pkgpath alias;
-type <type 115 "I1" <type 116 interface { M1 (? <type 117 "IntAlias2" = <type 118 "IntAlias" = <type 119 "Int" <type -11>>>>) < type 114>; M2 () <type 1>; }>>;

src/go/internal/gcimporter/bimport.go

@@ -98,10 +98,10 @@ func BImportData(fset *token.FileSet, imports map[string]*types.Package, data []
 
 	// read version specific flags - extend as necessary
 	switch p.version {
-	// case 5:
+	// case 4:
 	// 	...
 	//	fallthrough
-	case 4, 3, 2, 1:
+	case 3, 2, 1:
 		p.debugFormat = p.rawStringln(p.rawByte()) == "debug"
 		p.trackAllTypes = p.int() != 0
 		p.posInfoFormat = p.int() != 0
@@ -208,6 +208,7 @@ func (p *importer) pkg() *types.Package {
 }
 
 // objTag returns the tag value for each object kind.
+// obj must not be a *types.Alias.
 func objTag(obj types.Object) int {
 	switch obj.(type) {
 	case *types.Const:
@@ -218,6 +219,7 @@ func objTag(obj types.Object) int {
 		return varTag
 	case *types.Func:
 		return funcTag
+	// Aliases are not exported multiple times, thus we should not see them here.
 	default:
 		errorf("unexpected object: %v (%T)", obj, obj) // panics
 		panic("unreachable")
@@ -235,14 +237,14 @@ func (p *importer) declare(obj types.Object) {
 	pkg := obj.Pkg()
 	if alt := pkg.Scope().Insert(obj); alt != nil {
 		// This can only trigger if we import a (non-type) object a second time.
-		// Excluding type aliases, this cannot happen because 1) we only import a package
+		// Excluding aliases, this cannot happen because 1) we only import a package
 		// once; and b) we ignore compiler-specific export data which may contain
 		// functions whose inlined function bodies refer to other functions that
 		// were already imported.
-		// However, type aliases require reexporting the original type, so we need
+		// However, aliases require reexporting the original object, so we need
 		// to allow it (see also the comment in cmd/compile/internal/gc/bimport.go,
 		// method importer.obj, switch case importing functions).
-		// TODO(gri) review/update this comment once the gc compiler handles type aliases.
+		// Note that the original itself cannot be an alias.
 		if !sameObj(obj, alt) {
 			errorf("inconsistent import:\n\t%v\npreviously imported as:\n\t%v\n", obj, alt)
 		}
@@ -258,13 +260,6 @@ func (p *importer) obj(tag int) {
 		val := p.value()
 		p.declare(types.NewConst(pos, pkg, name, typ, val))
 
-	case aliasTag:
-		// TODO(gri) verify type alias hookup is correct
-		pos := p.pos()
-		pkg, name := p.qualifiedName()
-		typ := p.typ(nil)
-		p.declare(types.NewTypeName(pos, pkg, name, typ))
-
 	case typeTag:
 		p.typ(nil)
 
@@ -282,6 +277,19 @@ func (p *importer) obj(tag int) {
 		sig := types.NewSignature(nil, params, result, isddd)
 		p.declare(types.NewFunc(pos, pkg, name, sig))
 
+	case aliasTag:
+		pos := p.pos()
+		name := p.string()
+		var orig types.Object
+		if pkg, name := p.qualifiedName(); pkg != nil {
+			orig = pkg.Scope().Lookup(name)
+		}
+		// Alias-related code. Keep for now.
+		_ = pos
+		_ = name
+		_ = orig
+		// p.declare(types.NewAlias(pos, p.pkgList[0], name, orig))
+
 	default:
 		errorf("unexpected object tag %d", tag)
 	}
@@ -341,7 +349,9 @@ var (
 
 func (p *importer) qualifiedName() (pkg *types.Package, name string) {
 	name = p.string()
-	pkg = p.pkg()
+	if name != "" {
+		pkg = p.pkg()
+	}
 	return
 }
 
@@ -546,17 +556,17 @@ func (p *importer) fieldList(parent *types.Package) (fields []*types.Var, tags [
 		fields = make([]*types.Var, n)
 		tags = make([]string, n)
 		for i := range fields {
-			fields[i], tags[i] = p.field(parent)
+			fields[i] = p.field(parent)
+			tags[i] = p.string()
 		}
 	}
 	return
 }
 
-func (p *importer) field(parent *types.Package) (*types.Var, string) {
+func (p *importer) field(parent *types.Package) *types.Var {
 	pos := p.pos()
-	pkg, name, alias := p.fieldName(parent)
+	pkg, name := p.fieldName(parent)
 	typ := p.typ(parent)
-	tag := p.string()
 
 	anonymous := false
 	if name == "" {
@@ -568,15 +578,12 @@ func (p *importer) field(parent *types.Package) (*types.Var, string) {
 		case *types.Named:
 			name = typ.Obj().Name()
 		default:
-			errorf("named base type expected")
+			errorf("anonymous field expected")
 		}
 		anonymous = true
-	} else if alias {
-		// anonymous field: we have an explicit name because it's an alias
-		anonymous = true
 	}
 
-	return types.NewField(pos, pkg, name, typ, anonymous), tag
+	return types.NewField(pos, pkg, name, typ, anonymous)
 }
 
 func (p *importer) methodList(parent *types.Package) (methods []*types.Func) {
@@ -591,42 +598,31 @@ func (p *importer) methodList(parent *types.Package) (methods []*types.Func) {
 
 func (p *importer) method(parent *types.Package) *types.Func {
 	pos := p.pos()
-	pkg, name, _ := p.fieldName(parent)
+	pkg, name := p.fieldName(parent)
 	params, isddd := p.paramList()
 	result, _ := p.paramList()
 	sig := types.NewSignature(nil, params, result, isddd)
 	return types.NewFunc(pos, pkg, name, sig)
 }
 
-func (p *importer) fieldName(parent *types.Package) (pkg *types.Package, name string, alias bool) {
-	name = p.string()
-	pkg = parent
+func (p *importer) fieldName(parent *types.Package) (*types.Package, string) {
+	name := p.string()
+	pkg := parent
 	if pkg == nil {
 		// use the imported package instead
 		pkg = p.pkgList[0]
 	}
 	if p.version == 0 && name == "_" {
 		// version 0 didn't export a package for _ fields
-		return
+		return pkg, name
 	}
-	switch name {
-	case "":
-		// 1) field name matches base type name and is exported: nothing to do
-	case "?":
-		// 2) field name matches base type name and is not exported: need package
-		name = ""
-		pkg = p.pkg()
-	case "@":
-		// 3) field name doesn't match type name (alias)
-		name = p.string()
-		alias = true
-		fallthrough
-	default:
-		if !exported(name) {
-			pkg = p.pkg()
+	if name != "" && !exported(name) {
+		if name == "?" {
+			name = ""
 		}
+		pkg = p.pkg()
 	}
-	return
+	return pkg, name
 }
 
 func (p *importer) paramList() (*types.Tuple, bool) {
@@ -897,7 +893,7 @@ const (
 	nilTag     // only used by gc (appears in exported inlined function bodies)
 	unknownTag // not used by gc (only appears in packages with errors)
 
-	// Type aliases
+	// Aliases
 	aliasTag
 )
 
@@ -921,7 +917,7 @@ var predeclared = []types.Type{
 	types.Typ[types.Complex128],
 	types.Typ[types.String],
 
-	// basic type aliases
+	// aliases
 	types.Universe.Lookup("byte").Type(),
 	types.Universe.Lookup("rune").Type(),
 

src/go/parser/parser.go

@@ -2327,10 +2327,7 @@ func (p *parser) parseTypeSpec(doc *ast.CommentGroup, _ token.Token, _ int) ast.
 	// (Global identifiers are resolved in a separate phase after parsing.)
 	spec := &ast.TypeSpec{Doc: doc, Name: ident}
 	p.declare(spec, nil, p.topScope, ast.Typ, ident)
-	if p.tok == token.ASSIGN {
-		spec.Assign = p.pos
-		p.next()
-	}
+
 	spec.Type = p.parseType()
 	p.expectSemi() // call before accessing p.linecomment
 	spec.Comment = p.lineComment

src/go/parser/short_test.go

@@ -46,8 +46,6 @@ var valids = []string{
 	`package p; const (x = 0; y; z)`, // issue 9639
 	`package p; var _ = map[P]int{P{}:0, {}:1}`,
 	`package p; var _ = map[*P]int{&P{}:0, {}:1}`,
-	`package p; type T = int`,
-	`package p; type (T = p.T; _ = struct{}; x = *T)`,
 }
 
 func TestValid(t *testing.T) {

src/go/printer/nodes.go

@@ -1447,9 +1447,6 @@ func (p *printer) spec(spec ast.Spec, n int, doIndent bool) {
 		} else {
 			p.print(vtab)
 		}
-		if s.Assign.IsValid() {
-			p.print(token.ASSIGN, blank)
-		}
 		p.expr(s.Type)
 		p.setComment(s.Comment)
 

src/go/printer/testdata/declarations.golden

@@ -985,18 +985,3 @@ func _(struct {
 	x	int
 	y	int
 })	// no extra comma between } and )
-
-// alias declarations
-
-type c0 struct{}
-type c1 = C
-type c2 = struct{ x int }
-type c3 = p.C
-type (
-	s	struct{}
-	a	= A
-	b	= A
-	c	= foo
-	d	= interface{}
-	ddd	= p.Foo
-)

src/go/printer/testdata/declarations.input

@@ -999,18 +999,3 @@ func _(struct {
 	x int
 	y int
 }) // no extra comma between } and )
-
-// alias declarations
-
-type c0 struct{}
-type c1 = C
-type c2 = struct{ x int}
-type c3 = p.C
-type (
-	s struct{}
-	a = A
-	b = A
-	c = foo
-	d = interface{}
-	ddd = p.Foo
-)

src/go/types/api_test.go

@@ -1295,3 +1295,155 @@ func f(x int) { y := x; print(y) }
 		}
 	}
 }
+
+// Alias-related code. Keep for now.
+/*
+func TestAliases(t *testing.T) {
+	testenv.MustHaveGoBuild(t)
+
+	const src = `
+package b
+
+import (
+	"./testdata/alias"
+	a "./testdata/alias"
+	"math"
+)
+
+const (
+	c1 = alias.Pi1
+	c2 => a.Pi1
+	c3 => a.Pi2
+	c4 => math.Pi
+)
+
+var (
+	v1 => alias.Default
+	v2 => a.Default
+	v3 = f1
+)
+
+type (
+	t1 => alias.Context
+	t2 => a.Context
+)
+
+func f1 => alias.Sin
+func f2 => a.Sin
+
+func _() {
+	assert(c1 == alias.Pi1 && c2 == a.Pi1 && c3 == a.Pi2 && c4 == math.Pi)
+	assert(c2 == c2 && c2 == c3 && c3 == c4)
+	v1 = v2 // must be assignable
+	var _ *t1 = new(t2) // must be assignable
+	var _ t2 = alias.Default
+	f1(1) // must be callable
+	f2(1)
+	_ = alias.Sin(1)
+	_ = a.Sin(1)
+}
+`
+
+	if out := compile(t, "testdata", "alias.go"); out != "" {
+		defer os.Remove(out)
+	}
+
+	DefPredeclaredTestFuncs() // declare assert built-in for testing
+	mustTypecheck(t, "Aliases", src, nil)
+}
+
+func compile(t *testing.T, dirname, filename string) string {
+	cmd := exec.Command(testenv.GoToolPath(t), "tool", "compile", filename)
+	cmd.Dir = dirname
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		t.Logf("%s", out)
+		t.Fatalf("go tool compile %s failed: %s", filename, err)
+	}
+	// filename should end with ".go"
+	return filepath.Join(dirname, filename[:len(filename)-2]+"o")
+}
+
+func TestAliasDefUses(t *testing.T) {
+	testenv.MustHaveGoBuild(t)
+
+	const src = `
+package p
+
+import(
+	"go/build"
+	"go/types"
+)
+
+// Defs
+const Invalid => types.Invalid
+type Struct => types.Struct
+var Default => build.Default
+func Implements => types.Implements
+
+// Uses
+const _ = Invalid
+var _ types.Struct = Struct{} // types must be identical
+var _ build.Context = Default
+var _ = Implements(nil, nil)
+`
+
+	info := Info{
+		Defs: make(map[*ast.Ident]Object),
+		Uses: make(map[*ast.Ident]Object),
+	}
+	mustTypecheck(t, "TestAliasDefUses", src, &info)
+
+	// verify Defs
+	defs := map[string]string{
+		"Invalid":    "types.Invalid",
+		"Struct":     "types.Struct",
+		"Default":    "build.Default",
+		"Implements": "types.Implements",
+	}
+
+	for ident, obj := range info.Defs {
+		if alias, ok := obj.(*Alias); ok {
+			if want := defs[ident.Name]; want != "" {
+				orig := alias.Orig()
+				if got := orig.Pkg().Name() + "." + orig.Name(); got != want {
+					t.Errorf("%v: got %v, want %v", ident, got, want)
+				}
+				delete(defs, ident.Name) // mark as found
+			} else {
+				t.Errorf("unexpected alias def of %v", ident)
+			}
+		}
+	}
+
+	if len(defs) != 0 {
+		t.Errorf("missing aliases: %v", defs)
+	}
+
+	// verify Uses
+	uses := map[string]string{
+		"Invalid":    "types.Invalid",
+		"Struct":     "types.Struct",
+		"Default":    "build.Default",
+		"Implements": "types.Implements",
+	}
+
+	for ident, obj := range info.Uses {
+		if alias, ok := obj.(*Alias); ok {
+			if want := uses[ident.Name]; want != "" {
+				orig := alias.Orig()
+				if got := orig.Pkg().Name() + "." + orig.Name(); got != want {
+					t.Errorf("%v: got %v, want %v", ident, got, want)
+				}
+				delete(uses, ident.Name) // mark as found
+			} else {
+				t.Errorf("unexpected alias use of %v", ident)
+			}
+		}
+	}
+
+	if len(uses) != 0 {
+		t.Errorf("missing aliases: %v", defs)
+	}
+}
+*/

src/go/types/call.go

@@ -275,6 +275,8 @@ func (check *Checker) selector(x *operand, e *ast.SelectorExpr) {
 	// so we don't need a "package" mode for operands: package names
 	// can only appear in qualified identifiers which are mapped to
 	// selector expressions.
+	// (see also decl.go: checker.aliasDecl)
+	// TODO(gri) factor this code out and share with checker.aliasDecl
 	if ident, ok := e.X.(*ast.Ident); ok {
 		_, obj := check.scope.LookupParent(ident.Name, check.pos)
 		if pname, _ := obj.(*PkgName); pname != nil {
@@ -294,6 +296,12 @@ func (check *Checker) selector(x *operand, e *ast.SelectorExpr) {
 				// ok to continue
 			}
 			check.recordUse(e.Sel, exp)
+			exp = original(exp)
+
+			// avoid further errors if the imported object is an alias that's broken
+			if exp == nil {
+				goto Error
+			}
 
 			// Simplified version of the code for *ast.Idents:
 			// - imported objects are always fully initialized

src/go/types/check_test.go

@@ -68,11 +68,11 @@ var tests = [][]string{
 	{"testdata/decls1.src"},
 	{"testdata/decls2a.src", "testdata/decls2b.src"},
 	{"testdata/decls3.src"},
-	{"testdata/decls4.src"},
 	{"testdata/const0.src"},
 	{"testdata/const1.src"},
 	{"testdata/constdecl.src"},
 	{"testdata/vardecl.src"},
+	//{"testdata/aliasdecl.src"},
 	{"testdata/expr0.src"},
 	{"testdata/expr1.src"},
 	{"testdata/expr2.src"},

src/go/types/decl.go

@@ -81,10 +81,14 @@ func (check *Checker) objDecl(obj Object, def *Named, path []*TypeName) {
 		check.varDecl(obj, d.lhs, d.typ, d.init)
 	case *TypeName:
 		// invalid recursive types are detected via path
-		check.typeDecl(obj, d.typ, def, path, d.alias)
+		check.typeDecl(obj, d.typ, def, path)
 	case *Func:
 		// functions may be recursive - no need to track dependencies
 		check.funcDecl(obj, d)
+	// Alias-related code. Keep for now.
+	// case *Alias:
+	// 	// aliases cannot be recursive - no need to track dependencies
+	// 	check.aliasDecl(obj, d)
 	default:
 		unreachable()
 	}
@@ -215,42 +219,33 @@ func (n *Named) setUnderlying(typ Type) {
 	}
 }
 
-func (check *Checker) typeDecl(obj *TypeName, typ ast.Expr, def *Named, path []*TypeName, alias bool) {
+func (check *Checker) typeDecl(obj *TypeName, typ ast.Expr, def *Named, path []*TypeName) {
 	assert(obj.typ == nil)
 
 	// type declarations cannot use iota
 	assert(check.iota == nil)
 
-	if alias {
+	named := &Named{obj: obj}
+	def.setUnderlying(named)
+	obj.typ = named // make sure recursive type declarations terminate
 
-		obj.typ = Typ[Invalid]
-		obj.typ = check.typExpr(typ, nil, append(path, obj))
+	// determine underlying type of named
+	check.typExpr(typ, named, append(path, obj))
 
-	} else {
-
-		named := &Named{obj: obj}
-		def.setUnderlying(named)
-		obj.typ = named // make sure recursive type declarations terminate
-
-		// determine underlying type of named
-		check.typExpr(typ, named, append(path, obj))
-
-		// The underlying type of named may be itself a named type that is
-		// incomplete:
-		//
-		//	type (
-		//		A B
-		//		B *C
-		//		C A
-		//	)
-		//
-		// The type of C is the (named) type of A which is incomplete,
-		// and which has as its underlying type the named type B.
-		// Determine the (final, unnamed) underlying type by resolving
-		// any forward chain (they always end in an unnamed type).
-		named.underlying = underlying(named.underlying)
-
-	}
+	// The underlying type of named may be itself a named type that is
+	// incomplete:
+	//
+	//	type (
+	//		A B
+	//		B *C
+	//		C A
+	//	)
+	//
+	// The type of C is the (named) type of A which is incomplete,
+	// and which has as its underlying type the named type B.
+	// Determine the (final, unnamed) underlying type by resolving
+	// any forward chain (they always end in an unnamed type).
+	named.underlying = underlying(named.underlying)
 
 	// check and add associated methods
 	// TODO(gri) It's easy to create pathological cases where the
@@ -273,23 +268,21 @@ func (check *Checker) addMethodDecls(obj *TypeName) {
 
 	// spec: "If the base type is a struct type, the non-blank method
 	// and field names must be distinct."
-	base, _ := obj.typ.(*Named) // nil if receiver base type is type alias
-	if base != nil {
-		if t, _ := base.underlying.(*Struct); t != nil {
-			for _, fld := range t.fields {
-				if fld.name != "_" {
-					assert(mset.insert(fld) == nil)
-				}
+	base := obj.typ.(*Named)
+	if t, _ := base.underlying.(*Struct); t != nil {
+		for _, fld := range t.fields {
+			if fld.name != "_" {
+				assert(mset.insert(fld) == nil)
 			}
 		}
+	}
 
-		// Checker.Files may be called multiple times; additional package files
-		// may add methods to already type-checked types. Add pre-existing methods
-		// so that we can detect redeclarations.
-		for _, m := range base.methods {
-			assert(m.name != "_")
-			assert(mset.insert(m) == nil)
-		}
+	// Checker.Files may be called multiple times; additional package files
+	// may add methods to already type-checked types. Add pre-existing methods
+	// so that we can detect redeclarations.
+	for _, m := range base.methods {
+		assert(m.name != "_")
+		assert(mset.insert(m) == nil)
 	}
 
 	// type-check methods
@@ -302,7 +295,7 @@ func (check *Checker) addMethodDecls(obj *TypeName) {
 				case *Var:
 					check.errorf(m.pos, "field and method with the same name %s", m.name)
 				case *Func:
-					check.errorf(m.pos, "method %s already declared for %s", m.name, obj)
+					check.errorf(m.pos, "method %s already declared for %s", m.name, base)
 				default:
 					unreachable()
 				}
@@ -310,12 +303,9 @@ func (check *Checker) addMethodDecls(obj *TypeName) {
 				continue
 			}
 		}
-
-		// type-check
 		check.objDecl(m, nil, nil)
-
 		// methods with blank _ names cannot be found - don't keep them
-		if base != nil && m.name != "_" {
+		if m.name != "_" {
 			base.methods = append(base.methods, m)
 		}
 	}
@@ -343,6 +333,106 @@ func (check *Checker) funcDecl(obj *Func, decl *declInfo) {
 	}
 }
 
+// original returns the original Object if obj is an Alias;
+// otherwise it returns obj. The result is never an Alias,
+// but it may be nil.
+func original(obj Object) Object {
+	// an alias stands for the original object; use that one instead
+	if alias, _ := obj.(*disabledAlias); alias != nil {
+		obj = alias.orig
+		// aliases always refer to non-alias originals
+		if _, ok := obj.(*disabledAlias); ok {
+			panic("original is an alias")
+		}
+	}
+	return obj
+}
+
+func (check *Checker) aliasDecl(obj *disabledAlias, decl *declInfo) {
+	assert(obj.typ == nil)
+
+	// alias declarations cannot use iota
+	assert(check.iota == nil)
+
+	// assume alias is invalid to start with
+	obj.typ = Typ[Invalid]
+
+	// rhs must be package-qualified identifer pkg.sel (see also call.go: checker.selector)
+	// TODO(gri) factor this code out and share with checker.selector
+	rhs := decl.init
+	var pkg *Package
+	var sel *ast.Ident
+	if sexpr, ok := rhs.(*ast.SelectorExpr); ok {
+		if ident, ok := sexpr.X.(*ast.Ident); ok {
+			_, obj := check.scope.LookupParent(ident.Name, check.pos)
+			if pname, _ := obj.(*PkgName); pname != nil {
+				assert(pname.pkg == check.pkg)
+				check.recordUse(ident, pname)
+				pname.used = true
+				pkg = pname.imported
+				sel = sexpr.Sel
+			}
+		}
+	}
+	if pkg == nil {
+		check.errorf(rhs.Pos(), "invalid alias: %v is not a package-qualified identifier", rhs)
+		return
+	}
+
+	// qualified identifier must denote an exported object
+	orig := pkg.scope.Lookup(sel.Name)
+	if orig == nil || !orig.Exported() {
+		if !pkg.fake {
+			check.errorf(rhs.Pos(), "%s is not exported by package %s", sel.Name, pkg.name)
+		}
+		return
+	}
+	check.recordUse(sel, orig)
+	orig = original(orig)
+
+	// avoid further errors if the imported object is an alias that's broken
+	if orig == nil {
+		return
+	}
+
+	// An alias declaration must not refer to package unsafe.
+	if orig.Pkg() == Unsafe {
+		check.errorf(rhs.Pos(), "invalid alias: %s refers to package unsafe (%v)", obj.Name(), orig)
+		return
+	}
+
+	// The original must be of the same kind as the alias declaration.
+	var why string
+	switch obj.kind {
+	case token.CONST:
+		if _, ok := orig.(*Const); !ok {
+			why = "constant"
+		}
+	case token.TYPE:
+		if _, ok := orig.(*TypeName); !ok {
+			why = "type"
+		}
+	case token.VAR:
+		if _, ok := orig.(*Var); !ok {
+			why = "variable"
+		}
+	case token.FUNC:
+		if _, ok := orig.(*Func); !ok {
+			why = "function"
+		}
+	default:
+		unreachable()
+	}
+	if why != "" {
+		check.errorf(rhs.Pos(), "invalid alias: %v is not a %s", orig, why)
+		return
+	}
+
+	// alias is valid
+	obj.typ = orig.Type()
+	obj.orig = orig
+}
+
 func (check *Checker) declStmt(decl ast.Decl) {
 	pkg := check.pkg
 
@@ -450,7 +540,7 @@ func (check *Checker) declStmt(decl ast.Decl) {
 				// the innermost containing block."
 				scopePos := s.Name.Pos()
 				check.declare(check.scope, s.Name, obj, scopePos)
-				check.typeDecl(obj, s.Type, nil, nil, s.Assign.IsValid())
+				check.typeDecl(obj, s.Type, nil, nil)
 
 			default:
 				check.invalidAST(s.Pos(), "const, type, or var declaration expected")

src/go/types/example_test.go

@@ -239,10 +239,10 @@ func fib(x int) int {
 	// type S string:
 	//   defined at fib.go:4:6
 	//   used at 6:23
-	// type int:
+	// type int int:
 	//   defined at -
 	//   used at 8:12, 8:17
-	// type string:
+	// type string string:
 	//   defined at -
 	//   used at 4:8
 	// var b S:

src/go/types/lookup.go

@@ -67,22 +67,24 @@ func lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (o
 	}
 
 	typ, isPtr := deref(T)
+	named, _ := typ.(*Named)
 
 	// *typ where typ is an interface has no methods.
-	if isPtr && IsInterface(typ) {
-		return
+	if isPtr {
+		utyp := typ
+		if named != nil {
+			utyp = named.underlying
+		}
+		if _, ok := utyp.(*Interface); ok {
+			return
+		}
 	}
 
 	// Start with typ as single entry at shallowest depth.
-	current := []embeddedType{{typ, nil, isPtr, false}}
+	// If typ is not a named type, insert a nil type instead.
+	current := []embeddedType{{named, nil, isPtr, false}}
 
-	// Named types that we have seen already, allocated lazily.
-	// Used to avoid endless searches in case of recursive types.
-	// Since only Named types can be used for recursive types, we
-	// only need to track those.
-	// (If we ever allow type aliases to construct recursive types,
-	// we must use type identity rather than pointer equality for
-	// the map key comparison, as we do in consolidateMultiples.)
+	// named types that we have seen already, allocated lazily
 	var seen map[*Named]bool
 
 	// search current depth
@@ -91,12 +93,11 @@ func lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (o
 
 		// look for (pkg, name) in all types at current depth
 		for _, e := range current {
-			typ := e.typ
-
-			// If we have a named type, we may have associated methods.
-			// Look for those first.
-			if named, _ := typ.(*Named); named != nil {
-				if seen[named] {
+			// The very first time only, e.typ may be nil.
+			// In this case, we don't have a named type and
+			// we simply continue with the underlying type.
+			if e.typ != nil {
+				if seen[e.typ] {
 					// We have seen this type before, at a more shallow depth
 					// (note that multiples of this type at the current depth
 					// were consolidated before). The type at that depth shadows
@@ -107,10 +108,10 @@ func lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (o
 				if seen == nil {
 					seen = make(map[*Named]bool)
 				}
-				seen[named] = true
+				seen[e.typ] = true
 
 				// look for a matching attached method
-				if i, m := lookupMethod(named.methods, pkg, name); m != nil {
+				if i, m := lookupMethod(e.typ.methods, pkg, name); m != nil {
 					// potential match
 					assert(m.typ != nil)
 					index = concat(e.index, i)
@@ -123,7 +124,7 @@ func lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (o
 				}
 
 				// continue with underlying type
-				typ = named.underlying
+				typ = e.typ.underlying
 			}
 
 			switch t := typ.(type) {
@@ -146,15 +147,16 @@ func lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (o
 					// we have a name collision on the same depth; in either
 					// case we don't need to look further).
 					// Embedded fields are always of the form T or *T where
-					// T is a type name. If e.typ appeared multiple times at
+					// T is a named type. If e.typ appeared multiple times at
 					// this depth, f.typ appears multiple times at the next
 					// depth.
 					if obj == nil && f.anonymous {
+						// Ignore embedded basic types - only user-defined
+						// named types can have methods or struct fields.
 						typ, isPtr := deref(f.typ)
-						// TODO(gri) optimization: ignore types that can't
-						// have fields or methods (only Named, Struct, and
-						// Interface types need to be considered).
-						next = append(next, embeddedType{typ, concat(e.index, i), e.indirect || isPtr, e.multiples})
+						if t, _ := typ.(*Named); t != nil {
+							next = append(next, embeddedType{t, concat(e.index, i), e.indirect || isPtr, e.multiples})
+						}
 					}
 				}
 
@@ -191,12 +193,12 @@ func lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (o
 	return nil, nil, false // not found
 }
 
-// embeddedType represents an embedded type
+// embeddedType represents an embedded named type
 type embeddedType struct {
-	typ       Type
-	index     []int // embedded field indices, starting with index at depth 0
-	indirect  bool  // if set, there was a pointer indirection on the path to this field
-	multiples bool  // if set, typ appears multiple times at this depth
+	typ       *Named // nil means use the outer typ variable instead
+	index     []int  // embedded field indices, starting with index at depth 0
+	indirect  bool   // if set, there was a pointer indirection on the path to this field
+	multiples bool   // if set, typ appears multiple times at this depth
 }
 
 // consolidateMultiples collects multiple list entries with the same type
@@ -207,10 +209,10 @@ func consolidateMultiples(list []embeddedType) []embeddedType {
 		return list // at most one entry - nothing to do
 	}
 
-	n := 0                     // number of entries w/ unique type
-	prev := make(map[Type]int) // index at which type was previously seen
+	n := 0                       // number of entries w/ unique type
+	prev := make(map[*Named]int) // index at which type was previously seen
 	for _, e := range list {
-		if i, found := lookupType(prev, e.typ); found {
+		if i, found := prev[e.typ]; found {
 			list[i].multiples = true
 			// ignore this entry
 		} else {
@@ -222,21 +224,6 @@ func consolidateMultiples(list []embeddedType) []embeddedType {
 	return list[:n]
 }
 
-func lookupType(m map[Type]int, typ Type) (int, bool) {
-	// fast path: maybe the types are equal
-	if i, found := m[typ]; found {
-		return i, true
-	}
-
-	for t, i := range m {
-		if Identical(t, typ) {
-			return i, true
-		}
-	}
-
-	return 0, false
-}
-
 // MissingMethod returns (nil, false) if V implements T, otherwise it
 // returns a missing method required by T and whether it is missing or
 // just has the wrong type.

src/go/types/methodset.go

@@ -72,22 +72,24 @@ func NewMethodSet(T Type) *MethodSet {
 	var base methodSet
 
 	typ, isPtr := deref(T)
+	named, _ := typ.(*Named)
 
 	// *typ where typ is an interface has no methods.
-	if isPtr && IsInterface(typ) {
-		return &emptyMethodSet
+	if isPtr {
+		utyp := typ
+		if named != nil {
+			utyp = named.underlying
+		}
+		if _, ok := utyp.(*Interface); ok {
+			return &emptyMethodSet
+		}
 	}
 
 	// Start with typ as single entry at shallowest depth.
-	current := []embeddedType{{typ, nil, isPtr, false}}
+	// If typ is not a named type, insert a nil type instead.
+	current := []embeddedType{{named, nil, isPtr, false}}
 
-	// Named types that we have seen already, allocated lazily.
-	// Used to avoid endless searches in case of recursive types.
-	// Since only Named types can be used for recursive types, we
-	// only need to track those.
-	// (If we ever allow type aliases to construct recursive types,
-	// we must use type identity rather than pointer equality for
-	// the map key comparison, as we do in consolidateMultiples.)
+	// named types that we have seen already, allocated lazily
 	var seen map[*Named]bool
 
 	// collect methods at current depth
@@ -99,12 +101,11 @@ func NewMethodSet(T Type) *MethodSet {
 		var mset methodSet
 
 		for _, e := range current {
-			typ := e.typ
-
-			// If we have a named type, we may have associated methods.
-			// Look for those first.
-			if named, _ := typ.(*Named); named != nil {
-				if seen[named] {
+			// The very first time only, e.typ may be nil.
+			// In this case, we don't have a named type and
+			// we simply continue with the underlying type.
+			if e.typ != nil {
+				if seen[e.typ] {
 					// We have seen this type before, at a more shallow depth
 					// (note that multiples of this type at the current depth
 					// were consolidated before). The type at that depth shadows
@@ -115,12 +116,12 @@ func NewMethodSet(T Type) *MethodSet {
 				if seen == nil {
 					seen = make(map[*Named]bool)
 				}
-				seen[named] = true
+				seen[e.typ] = true
 
-				mset = mset.add(named.methods, e.index, e.indirect, e.multiples)
+				mset = mset.add(e.typ.methods, e.index, e.indirect, e.multiples)
 
 				// continue with underlying type
-				typ = named.underlying
+				typ = e.typ.underlying
 			}
 
 			switch t := typ.(type) {
@@ -129,15 +130,16 @@ func NewMethodSet(T Type) *MethodSet {
 					fset = fset.add(f, e.multiples)
 
 					// Embedded fields are always of the form T or *T where
-					// T is a type name. If typ appeared multiple times at
+					// T is a named type. If typ appeared multiple times at
 					// this depth, f.Type appears multiple times at the next
 					// depth.
 					if f.anonymous {
+						// Ignore embedded basic types - only user-defined
+						// named types can have methods or struct fields.
 						typ, isPtr := deref(f.typ)
-						// TODO(gri) optimization: ignore types that can't
-						// have fields or methods (only Named, Struct, and
-						// Interface types need to be considered).
-						next = append(next, embeddedType{typ, concat(e.index, i), e.indirect || isPtr, e.multiples})
+						if t, _ := typ.(*Named); t != nil {
+							next = append(next, embeddedType{t, concat(e.index, i), e.indirect || isPtr, e.multiples})
+						}
 					}
 				}
 

src/go/types/object.go

@@ -25,7 +25,7 @@ type Object interface {
 	Name() string   // package local object name
 	Type() Type     // object type
 	Exported() bool // reports whether the name starts with a capital letter
-	Id() string     // object name if exported, qualified name if not exported (see func Id)
+	Id() string     // object id (see Id below)
 
 	// String returns a human-readable string of the object.
 	String() string
@@ -64,10 +64,15 @@ func Id(pkg *Package, name string) string {
 	// inside a package and outside a package - which breaks some
 	// tests)
 	path := "_"
-	// pkg is nil for objects in Universe scope and possibly types
-	// introduced via Eval (see also comment in object.sameId)
-	if pkg != nil && pkg.path != "" {
+	// TODO(gri): shouldn't !ast.IsExported(name) => pkg != nil be an precondition?
+	// if pkg == nil {
+	// 	panic("nil package in lookup of unexported name")
+	// }
+	if pkg != nil {
 		path = pkg.path
+		if path == "" {
+			path = "_"
+		}
 	}
 	return path + "." + name
 }
@@ -149,7 +154,7 @@ func NewConst(pos token.Pos, pkg *Package, name string, typ Type, val constant.V
 func (obj *Const) Val() constant.Value { return obj.val }
 func (*Const) isDependency()           {} // a constant may be a dependency of an initialization expression
 
-// A TypeName represents a name for a (named or alias) type.
+// A TypeName represents a declared type.
 type TypeName struct {
 	object
 }
@@ -158,26 +163,6 @@ func NewTypeName(pos token.Pos, pkg *Package, name string, typ Type) *TypeName {
 	return &TypeName{object{nil, pos, pkg, name, typ, 0, token.NoPos}}
 }
 
-// IsAlias reports whether obj is an alias name for a type.
-func (obj *TypeName) IsAlias() bool {
-	switch t := obj.typ.(type) {
-	case nil:
-		return false
-	case *Basic:
-		// Any user-defined type name for a basic type is an alias for a
-		// basic type (because basic types are pre-declared in the Universe
-		// scope, outside any package scope), and so is any type name with
-		// a different name than the name of the basic type it refers to.
-		// Additionaly, we need to look for "byte" and "rune" because they
-		// are aliases but have the same names (for better error messages).
-		return obj.pkg != nil || t.name != obj.name || t == universeByte || t == universeRune
-	case *Named:
-		return obj != t.obj
-	default:
-		return true
-	}
-}
-
 // A Variable represents a declared variable (including function parameters and results, and struct fields).
 type Var struct {
 	object
@@ -230,6 +215,28 @@ func (obj *Func) FullName() string {
 func (obj *Func) Scope() *Scope { return obj.typ.(*Signature).scope }
 func (*Func) isDependency()     {} // a function may be a dependency of an initialization expression
 
+// An Alias represents a declared alias.
+type disabledAlias struct {
+	object
+	orig Object      // aliased constant, type, variable, or function; never an alias
+	kind token.Token // token.CONST, token.TYPE, token.VAR, or token.FUNC (only needed during resolve phase)
+}
+
+func disabledNewAlias(pos token.Pos, pkg *Package, name string, orig Object) *disabledAlias {
+	var typ Type = Typ[Invalid]
+	if orig != nil {
+		typ = orig.Type()
+	}
+	// No need to set a valid Alias.kind - that field is only used during identifier
+	// resolution (1st type-checker pass). We could store the field outside but it's
+	// easier to keep it here.
+	return &disabledAlias{object{nil, pos, pkg, name, typ, 0, token.NoPos}, orig, token.ILLEGAL}
+}
+
+// Orig returns the aliased object, or nil if there was an error.
+// The returned object is never an Alias.
+func (obj *disabledAlias) disabledOrig() Object { return obj.orig }
+
 // A Label represents a declared label.
 type Label struct {
 	object
@@ -257,9 +264,7 @@ type Nil struct {
 }
 
 func writeObject(buf *bytes.Buffer, obj Object, qf Qualifier) {
-	var tname *TypeName
 	typ := obj.Type()
-
 	switch obj := obj.(type) {
 	case *PkgName:
 		fmt.Fprintf(buf, "package %s", obj.Name())
@@ -272,8 +277,8 @@ func writeObject(buf *bytes.Buffer, obj Object, qf Qualifier) {
 		buf.WriteString("const")
 
 	case *TypeName:
-		tname = obj
 		buf.WriteString("type")
+		typ = typ.Underlying()
 
 	case *Var:
 		if obj.isField {
@@ -290,6 +295,10 @@ func writeObject(buf *bytes.Buffer, obj Object, qf Qualifier) {
 		}
 		return
 
+	// Alias-related code. Keep for now.
+	// case *Alias:
+	// 	buf.WriteString("alias")
+
 	case *Label:
 		buf.WriteString("label")
 		typ = nil
@@ -313,27 +322,10 @@ func writeObject(buf *bytes.Buffer, obj Object, qf Qualifier) {
 		writePackage(buf, obj.Pkg(), qf)
 	}
 	buf.WriteString(obj.Name())
-
-	if typ == nil {
-		return
+	if typ != nil {
+		buf.WriteByte(' ')
+		WriteType(buf, typ, qf)
 	}
-
-	if tname != nil {
-		// We have a type object: Don't print anything more for
-		// basic types since there's no more information (names
-		// are the same; see also comment in TypeName.IsAlias).
-		if _, ok := typ.(*Basic); ok {
-			return
-		}
-		if tname.IsAlias() {
-			buf.WriteString(" =")
-		} else {
-			typ = typ.Underlying()
-		}
-	}
-
-	buf.WriteByte(' ')
-	WriteType(buf, typ, qf)
 }
 
 func writePackage(buf *bytes.Buffer, pkg *Package, qf Qualifier) {
@@ -361,14 +353,15 @@ func ObjectString(obj Object, qf Qualifier) string {
 	return buf.String()
 }
 
-func (obj *PkgName) String() string  { return ObjectString(obj, nil) }
-func (obj *Const) String() string    { return ObjectString(obj, nil) }
-func (obj *TypeName) String() string { return ObjectString(obj, nil) }
-func (obj *Var) String() string      { return ObjectString(obj, nil) }
-func (obj *Func) String() string     { return ObjectString(obj, nil) }
-func (obj *Label) String() string    { return ObjectString(obj, nil) }
-func (obj *Builtin) String() string  { return ObjectString(obj, nil) }
-func (obj *Nil) String() string      { return ObjectString(obj, nil) }
+func (obj *PkgName) String() string       { return ObjectString(obj, nil) }
+func (obj *Const) String() string         { return ObjectString(obj, nil) }
+func (obj *TypeName) String() string      { return ObjectString(obj, nil) }
+func (obj *Var) String() string           { return ObjectString(obj, nil) }
+func (obj *Func) String() string          { return ObjectString(obj, nil) }
+func (obj *disabledAlias) String() string { return ObjectString(obj, nil) }
+func (obj *Label) String() string         { return ObjectString(obj, nil) }
+func (obj *Builtin) String() string       { return ObjectString(obj, nil) }
+func (obj *Nil) String() string           { return ObjectString(obj, nil) }
 
 func writeFuncName(buf *bytes.Buffer, f *Func, qf Qualifier) {
 	if f.typ != nil {

src/go/types/object_test.go

@@ -1,43 +0,0 @@
-// Copyright 2016 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package types
-
-import "testing"
-
-func TestIsAlias(t *testing.T) {
-	check := func(obj *TypeName, want bool) {
-		if got := obj.IsAlias(); got != want {
-			t.Errorf("%v: got IsAlias = %v; want %v", obj, got, want)
-		}
-	}
-
-	// predeclared types
-	for _, name := range Universe.Names() {
-		if obj, _ := Universe.Lookup(name).(*TypeName); obj != nil {
-			check(obj, name == "byte" || name == "rune")
-		}
-	}
-
-	// various other types
-	pkg := NewPackage("p", "p")
-	t1 := NewTypeName(0, pkg, "t1", nil)
-	n1 := NewNamed(t1, new(Struct), nil)
-	for _, test := range []struct {
-		name  *TypeName
-		alias bool
-	}{
-		{NewTypeName(0, nil, "t0", nil), false}, // no type yet
-		{NewTypeName(0, pkg, "t0", nil), false}, // no type yet
-		{t1, false},                             // type name refers to named type and vice versa
-		{NewTypeName(0, nil, "t2", new(Interface)), true}, // type name refers to unnamed type
-		{NewTypeName(0, pkg, "t3", n1), true},             // type name refers to named type with different type name
-		{NewTypeName(0, nil, "t4", Typ[Int32]), true},     // type name refers to basic type with different name
-		{NewTypeName(0, nil, "int32", Typ[Int32]), false}, // type name refers to basic type with same name
-		{NewTypeName(0, pkg, "int32", Typ[Int32]), true},  // type name is declared in user-defined package (outside Universe)
-		{NewTypeName(0, nil, "rune", Typ[Rune]), true},    // type name refers to basic type rune which is an alias already
-	} {
-		check(test.name, test.alias)
-	}
-}

src/go/types/predicates.go

@@ -139,7 +139,7 @@ func identical(x, y Type, cmpTags bool, p *ifacePair) bool {
 	case *Basic:
 		// Basic types are singletons except for the rune and byte
 		// aliases, thus we cannot solely rely on the x == y check
-		// above. See also comment in TypeName.IsAlias.
+		// above.
 		if y, ok := y.(*Basic); ok {
 			return x.kind == y.kind
 		}

src/go/types/resolver.go

@@ -14,14 +14,13 @@ import (
 	"unicode"
 )
 
-// A declInfo describes a package-level const, type, var, or func declaration.
+// A declInfo describes a package-level const, type, var, func, or alias declaration.
 type declInfo struct {
 	file  *Scope        // scope of file containing this declaration
 	lhs   []*Var        // lhs of n:1 variable declarations, or nil
 	typ   ast.Expr      // type, or nil
 	init  ast.Expr      // init/orig expression, or nil
 	fdecl *ast.FuncDecl // func declaration, or nil
-	alias bool          // type alias declaration
 
 	// The deps field tracks initialization expression dependencies.
 	// As a special (overloaded) case, it also tracks dependencies of
@@ -275,6 +274,13 @@ func (check *Checker) collectObjects() {
 							check.declare(fileScope, nil, obj, token.NoPos)
 						}
 
+					// Alias-related code. Keep for now.
+					// case *ast.AliasSpec:
+					// 	obj := NewAlias(s.Name.Pos(), pkg, s.Name.Name, nil)
+					// 	obj.typ = nil // unresolved
+					// 	obj.kind = d.Tok
+					// 	check.declarePkgObj(s.Name, obj, &declInfo{file: fileScope, init: s.Orig})
+
 					case *ast.ValueSpec:
 						switch d.Tok {
 						case token.CONST:
@@ -341,7 +347,7 @@ func (check *Checker) collectObjects() {
 
 					case *ast.TypeSpec:
 						obj := NewTypeName(s.Name.Pos(), pkg, s.Name.Name, nil)
-						check.declarePkgObj(s.Name, obj, &declInfo{file: fileScope, typ: s.Type, alias: s.Assign.IsValid()})
+						check.declarePkgObj(s.Name, obj, &declInfo{file: fileScope, typ: s.Type})
 
 					default:
 						check.invalidAST(s.Pos(), "unknown ast.Spec node %T", s)

src/go/types/testdata/decls4.src

@@ -1,150 +0,0 @@
-// Copyright 2016 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// type aliases
-
-package decls4
-
-type (
-	T0 [10]int
-	T1 []byte
-	T2 struct {
-		x int
-	}
-	T3 interface{
-		m() T2
-	}
-	T4 func(int, T0) chan T2
-)
-
-type (
-	Ai = int
-	A0 = T0
-	A1 = T1
-	A2 = T2
-	A3 = T3
-	A4 = T4
-
-	A10 = [10]int
-	A11 = []byte
-	A12 = struct {
-		x int
-	}
-	A13 = interface{
-		m() A2
-	}
-	A14 = func(int, A0) chan A2
-)
-
-// check assignment compatibility due to equality of types
-var (
-	xi_ int
-	ai Ai = xi_
-
-	x0 T0
-	a0 A0 = x0
-
-	x1 T1
-	a1 A1 = x1
-
-	x2 T2
-	a2 A2 = x2
-
-	x3 T3
-	a3 A3 = x3
-
-	x4 T4
-	a4 A4 = x4
-)
-
-// alias receiver types
-func (Ai /* ERROR "invalid receiver" */) m1() {}
-func (T0) m1() {}
-func (A0) m1 /* ERROR already declared */ () {}
-func (A0) m2 () {}
-func (A3 /* ERROR invalid receiver */ ) m1 () {}
-func (A10 /* ERROR invalid receiver */ ) m1() {}
-
-// x0 has methods m1, m2 declared via receiver type names T0 and A0
-var _ interface{ m1(); m2() } = x0
-
-// cycles
-type (
-	C2 /* ERROR illegal cycle */ = C2
-	C3 /* ERROR illegal cycle */ = C4
-	C4 = C3
-	C5 struct {
-		f *C6
-	}
-	C6 = C5
-	C7 /* ERROR illegal cycle */  struct {
-		f C8
-	}
-	C8 = C7
-)
-
-// embedded fields
-var (
-	s0 struct { T0 }
-	s1 struct { A0 } = s0 /* ERROR cannot use */ // embedded field names are different
-)
-
-// embedding and lookup of fields and methods
-func _(s struct{A0}) { s.A0 = x0 }
-
-type eX struct{xf int}
-
-func (eX) xm()
-
-type eY = struct{eX} // field/method set of eY includes xf, xm
-
-type eZ = *struct{eX} // field/method set of eZ includes xf, xm
-
-type eA struct {
-	eX // eX contributes xf, xm to eA
-}
-
-type eA2 struct {
-	*eX // *eX contributes xf, xm to eA
-}
-
-type eB struct {
-	eY // eY contributes xf, xm to eB
-}
-
-type eB2 struct {
-	*eY // *eY contributes xf, xm to eB
-}
-
-type eC struct {
-	eZ // eZ contributes xf, xm to eC
-}
-
-var (
-	_ = eA{}.xf
-	_ = eA{}.xm
-	_ = eA2{}.xf
-	_ = eA2{}.xm
-	_ = eB{}.xf
-	_ = eB{}.xm
-	_ = eB2{}.xf
-	_ = eB2{}.xm
-	_ = eC{}.xf
-	_ = eC{}.xm
-)
-
-// ambiguous selectors due to embedding via type aliases
-type eD struct {
-	eY
-	eZ
-}
-
-var (
-	_ = eD /* ERROR ambiguous selector */ {}.xf
-	_ = eD /* ERROR ambiguous selector */ {}.xm
-)
-
-var (
-	_ interface{ xm() } = eD /* ERROR missing method xm */ {}
-)

src/go/types/typestring.go

@@ -56,7 +56,6 @@ func RelativeTo(pkg *Package) Qualifier {
 // This flag is exported in the x/tools/go/types package. We don't
 // need it at the moment in the std repo and so we don't export it
 // anymore. We should eventually try to remove it altogether.
-// TODO(gri) remove this
 var gcCompatibilityMode bool
 
 // TypeString returns the string representation of typ.

src/go/types/typexpr.go

@@ -45,6 +45,17 @@ func (check *Checker) ident(x *operand, e *ast.Ident, def *Named, path []*TypeNa
 		delete(check.unusedDotImports[scope], pkg)
 	}
 
+	// Alias-related code. Keep for now.
+	// An alias stands for the original object; use that one instead.
+	// TODO(gri) We should be able to factor out the Typ[Invalid] test.
+	// if alias, _ := obj.(*Alias); alias != nil {
+	// 	obj = original(obj)
+	// 	if obj == nil || typ == Typ[Invalid] {
+	// 		return
+	// 	}
+	// 	assert(typ == obj.Type())
+	// }
+
 	switch obj := obj.(type) {
 	case *PkgName:
 		check.errorf(e.Pos(), "use of package %s not in selector", obj.name)
@@ -650,41 +661,47 @@ func (check *Checker) structType(styp *Struct, e *ast.StructType, path []*TypeNa
 			}
 		} else {
 			// anonymous field
-			// spec: "An embedded type must be specified as a type name T or as a pointer
-			// to a non-interface type name *T, and T itself may not be a pointer type."
-			pos := f.Type.Pos()
 			name := anonymousFieldIdent(f.Type)
-			if name == nil {
-				check.invalidAST(pos, "anonymous field type %s has no name", f.Type)
-				continue
-			}
+			pos := f.Type.Pos()
 			t, isPtr := deref(typ)
-			// Because we have a name, typ must be of the form T or *T, where T is the name
-			// of a (named or alias) type, and t (= deref(typ)) must be the type of T.
-			switch t := t.Underlying().(type) {
+			switch t := t.(type) {
 			case *Basic:
 				if t == Typ[Invalid] {
 					// error was reported before
 					continue
 				}
-
 				// unsafe.Pointer is treated like a regular pointer
 				if t.kind == UnsafePointer {
 					check.errorf(pos, "anonymous field type cannot be unsafe.Pointer")
 					continue
 				}
+				add(f, name, true, pos)
 
-			case *Pointer:
-				check.errorf(pos, "anonymous field type cannot be a pointer")
-				continue
-
-			case *Interface:
-				if isPtr {
-					check.errorf(pos, "anonymous field type cannot be a pointer to an interface")
+			case *Named:
+				// spec: "An embedded type must be specified as a type name
+				// T or as a pointer to a non-interface type name *T, and T
+				// itself may not be a pointer type."
+				switch u := t.underlying.(type) {
+				case *Basic:
+					// unsafe.Pointer is treated like a regular pointer
+					if u.kind == UnsafePointer {
+						check.errorf(pos, "anonymous field type cannot be unsafe.Pointer")
+						continue
+					}
+				case *Pointer:
+					check.errorf(pos, "anonymous field type cannot be a pointer")
 					continue
+				case *Interface:
+					if isPtr {
+						check.errorf(pos, "anonymous field type cannot be a pointer to an interface")
+						continue
+					}
 				}
+				add(f, name, true, pos)
+
+			default:
+				check.invalidAST(pos, "anonymous field type %s must be named", typ)
 			}
-			add(f, name, true, pos)
 		}
 	}
 
@@ -697,10 +714,7 @@ func anonymousFieldIdent(e ast.Expr) *ast.Ident {
 	case *ast.Ident:
 		return e
 	case *ast.StarExpr:
-		// *T is valid, but **T is not
-		if _, ok := e.X.(*ast.StarExpr); !ok {
-			return anonymousFieldIdent(e.X)
-		}
+		return anonymousFieldIdent(e.X)
 	case *ast.SelectorExpr:
 		return e.Sel
 	}

src/math/big/int_test.go

@@ -1487,6 +1487,26 @@ func TestSqrt(t *testing.T) {
 	}
 }
 
+// We can't test this together with the other Exp tests above because
+// it requires a different receiver setup.
+func TestIssue22830(t *testing.T) {
+	one := new(Int).SetInt64(1)
+	base, _ := new(Int).SetString("84555555300000000000", 10)
+	mod, _ := new(Int).SetString("66666670001111111111", 10)
+	want, _ := new(Int).SetString("17888885298888888889", 10)
+
+	var tests = []int64{
+		0, 1, -1,
+	}
+
+	for _, n := range tests {
+		m := NewInt(n)
+		if got := m.Exp(base, one, mod); got.Cmp(want) != 0 {
+			t.Errorf("(%v).Exp(%s, 1, %s) = %s, want %s", n, base, mod, got, want)
+		}
+	}
+}
+
 func BenchmarkSqrt(b *testing.B) {
 	n, _ := new(Int).SetString("1"+strings.Repeat("0", 1001), 10)
 	b.ResetTimer()

src/math/big/nat.go

@@ -575,8 +575,8 @@ func (z nat) divLarge(u, uIn, v nat) (q, r nat) {
 	// determine if z can be reused
 	// TODO(gri) should find a better solution - this if statement
 	//           is very costly (see e.g. time pidigits -s -n 10000)
-	if alias(z, uIn) || alias(z, v) {
-		z = nil // z is an alias for uIn or v - cannot reuse
+	if alias(z, u) || alias(z, uIn) || alias(z, v) {
+		z = nil // z is an alias for u or uIn or v - cannot reuse
 	}
 	q = z.make(m + 1)
 

src/net/dial_test.go

@@ -225,6 +225,8 @@ func dialClosedPort() (actual, expected time.Duration) {
 	// but other platforms should be instantaneous.
 	if runtime.GOOS == "windows" {
 		expected = 1500 * time.Millisecond
+	} else if runtime.GOOS == "darwin" {
+		expected = 150 * time.Millisecond
 	} else {
 		expected = 95 * time.Millisecond
 	}

src/net/http/fs_test.go

@@ -1091,7 +1091,12 @@ func TestLinuxSendfile(t *testing.T) {
 		// and will error out if we specify that with `-e trace='.
 		syscalls = "sendfile"
 	case "mips64":
-		t.Skip("TODO: update this test to be robust against various versions of strace on mips64. See golang.org/issue/33430")
+		t.Skip("TODO: update this test to be robust against various versions of strace on mips64. See golang.org/issue/18008")
+	}
+
+	// Attempt to run strace, and skip on failure - this test requires SYS_PTRACE.
+	if err := exec.Command("strace", "-f", "-q", "-e", "trace="+syscalls, os.Args[0], "-test.run=^$").Run(); err != nil {
+		t.Skipf("skipping; failed to run strace: %v", err)
 	}
 
 	var buf bytes.Buffer

src/net/net_windows_test.go

@@ -503,21 +503,26 @@ func TestInterfaceAddrsWithNetsh(t *testing.T) {
 	}
 }
 
-func getmacSpeaksEnglish(t *testing.T) bool {
+// check that getmac exists as a powershell command, and that it
+// speaks English.
+func checkGetmac(t *testing.T) {
 	out, err := runCmd("getmac", "/?")
 	if err != nil {
+		if strings.Contains(err.Error(), "term 'getmac' is not recognized as the name of a cmdlet") {
+			t.Skipf("getmac not available")
+		}
 		t.Fatal(err)
 	}
-	return bytes.Contains(out, []byte("network adapters on a system"))
+	if !bytes.Contains(out, []byte("network adapters on a system")) {
+		t.Skipf("skipping test on non-English system")
+	}
 }
 
 func TestInterfaceHardwareAddrWithGetmac(t *testing.T) {
 	if isWindowsXP(t) {
 		t.Skip("Windows XP does not have powershell command")
 	}
-	if !getmacSpeaksEnglish(t) {
-		t.Skip("English version of getmac required for this test")
-	}
+	checkGetmac(t)
 
 	ift, err := Interfaces()
 	if err != nil {

src/net/smtp/auth.go

@@ -44,26 +44,29 @@ type plainAuth struct {
 }
 
 // PlainAuth returns an Auth that implements the PLAIN authentication
-// mechanism as defined in RFC 4616.
-// The returned Auth uses the given username and password to authenticate
-// on TLS connections to host and act as identity. Usually identity will be
-// left blank to act as username.
+// mechanism as defined in RFC 4616. The returned Auth uses the given
+// username and password to authenticate to host and act as identity.
+// Usually identity should be the empty string, to act as username.
+//
+// PlainAuth will only send the credentials if the connection is using TLS
+// or is connected to localhost. Otherwise authentication will fail with an
+// error, without sending the credentials.
 func PlainAuth(identity, username, password, host string) Auth {
 	return &plainAuth{identity, username, password, host}
 }
 
+func isLocalhost(name string) bool {
+	return name == "localhost" || name == "127.0.0.1" || name == "::1"
+}
+
 func (a *plainAuth) Start(server *ServerInfo) (string, []byte, error) {
-	if !server.TLS {
-		advertised := false
-		for _, mechanism := range server.Auth {
-			if mechanism == "PLAIN" {
-				advertised = true
-				break
-			}
-		}
-		if !advertised {
-			return "", nil, errors.New("unencrypted connection")
-		}
+	// Must have TLS, or else localhost server.
+	// Note: If TLS is not true, then we can't trust ANYTHING in ServerInfo.
+	// In particular, it doesn't matter if the server advertises PLAIN auth.
+	// That might just be the attacker saying
+	// "it's ok, you can trust me with your password."
+	if !server.TLS && !isLocalhost(server.Name) {
+		return "", nil, errors.New("unencrypted connection")
 	}
 	if server.Name != a.host {
 		return "", nil, errors.New("wrong host name")

src/net/smtp/smtp.go

@@ -67,6 +67,7 @@ func NewClient(conn net.Conn, host string) (*Client, error) {
 		return nil, err
 	}
 	c := &Client{Text: text, conn: conn, serverName: host, localName: "localhost"}
+	_, c.tls = conn.(*tls.Conn)
 	return c, nil
 }
 

src/net/smtp/smtp_test.go

@@ -60,29 +60,41 @@ testLoop:
 }
 
 func TestAuthPlain(t *testing.T) {
-	auth := PlainAuth("foo", "bar", "baz", "servername")
 
 	tests := []struct {
-		server *ServerInfo
-		err    string
+		authName string
+		server   *ServerInfo
+		err      string
 	}{
 		{
-			server: &ServerInfo{Name: "servername", TLS: true},
+			authName: "servername",
+			server:   &ServerInfo{Name: "servername", TLS: true},
 		},
 		{
-			// Okay; explicitly advertised by server.
-			server: &ServerInfo{Name: "servername", Auth: []string{"PLAIN"}},
+			// OK to use PlainAuth on localhost without TLS
+			authName: "localhost",
+			server:   &ServerInfo{Name: "localhost", TLS: false},
 		},
 		{
-			server: &ServerInfo{Name: "servername", Auth: []string{"CRAM-MD5"}},
-			err:    "unencrypted connection",
+			// NOT OK on non-localhost, even if server says PLAIN is OK.
+			// (We don't know that the server is the real server.)
+			authName: "servername",
+			server:   &ServerInfo{Name: "servername", Auth: []string{"PLAIN"}},
+			err:      "unencrypted connection",
 		},
 		{
-			server: &ServerInfo{Name: "attacker", TLS: true},
-			err:    "wrong host name",
+			authName: "servername",
+			server:   &ServerInfo{Name: "servername", Auth: []string{"CRAM-MD5"}},
+			err:      "unencrypted connection",
+		},
+		{
+			authName: "servername",
+			server:   &ServerInfo{Name: "attacker", TLS: true},
+			err:      "wrong host name",
 		},
 	}
 	for i, tt := range tests {
+		auth := PlainAuth("foo", "bar", "baz", tt.authName)
 		_, _, err := auth.Start(tt.server)
 		got := ""
 		if err != nil {
@@ -350,6 +362,53 @@ HELO localhost
 QUIT
 `
 
+func TestNewClientWithTLS(t *testing.T) {
+	cert, err := tls.X509KeyPair(localhostCert, localhostKey)
+	if err != nil {
+		t.Fatalf("loadcert: %v", err)
+	}
+
+	config := tls.Config{Certificates: []tls.Certificate{cert}}
+
+	ln, err := tls.Listen("tcp", "127.0.0.1:0", &config)
+	if err != nil {
+		ln, err = tls.Listen("tcp", "[::1]:0", &config)
+		if err != nil {
+			t.Fatalf("server: listen: %s", err)
+		}
+	}
+
+	go func() {
+		conn, err := ln.Accept()
+		if err != nil {
+			t.Fatalf("server: accept: %s", err)
+			return
+		}
+		defer conn.Close()
+
+		_, err = conn.Write([]byte("220 SIGNS\r\n"))
+		if err != nil {
+			t.Fatalf("server: write: %s", err)
+			return
+		}
+	}()
+
+	config.InsecureSkipVerify = true
+	conn, err := tls.Dial("tcp", ln.Addr().String(), &config)
+	if err != nil {
+		t.Fatalf("client: dial: %s", err)
+	}
+	defer conn.Close()
+
+	client, err := NewClient(conn, ln.Addr().String())
+	if err != nil {
+		t.Fatalf("smtp: newclient: %s", err)
+	}
+	if !client.tls {
+		t.Errorf("client.tls Got: %t Expected: %t", client.tls, true)
+	}
+}
+
 func TestHello(t *testing.T) {
 
 	if len(helloServer) != len(helloClient) {

src/os/os_windows_test.go

@@ -404,6 +404,8 @@ func TestDirectorySymbolicLink(t *testing.T) {
 func TestNetworkSymbolicLink(t *testing.T) {
 	testenv.MustHaveSymlink(t)
 
+	const _NERR_ServerNotStarted = syscall.Errno(2114)
+
 	dir, err := ioutil.TempDir("", "TestNetworkSymbolicLink")
 	if err != nil {
 		t.Fatal(err)
@@ -454,6 +456,9 @@ func TestNetworkSymbolicLink(t *testing.T) {
 		if err == syscall.ERROR_ACCESS_DENIED {
 			t.Skip("you don't have enough privileges to add network share")
 		}
+		if err == _NERR_ServerNotStarted {
+			t.Skip(_NERR_ServerNotStarted.Error())
+		}
 		t.Fatal(err)
 	}
 	defer func() {

src/reflect/all_test.go

@@ -3731,7 +3731,7 @@ func checkSameType(t *testing.T, x, y interface{}) {
 
 func TestArrayOf(t *testing.T) {
 	// check construction and use of type not in binary
-	tests := []struct {
+	for _, table := range []struct {
 		n          int
 		value      func(i int) interface{}
 		comparable bool
@@ -3809,9 +3809,7 @@ func TestArrayOf(t *testing.T) {
 			comparable: true,
 			want:       "[{0 0} {1 1} {2 2} {3 3} {4 4} {5 5} {6 6} {7 7} {8 8} {9 9}]",
 		},
-	}
-
-	for _, table := range tests {
+	} {
 		at := ArrayOf(table.n, TypeOf(table.value(0)))
 		v := New(at).Elem()
 		vok := New(at).Elem()
@@ -4177,58 +4175,50 @@ func TestStructOfExportRules(t *testing.T) {
 		f()
 	}
 
-	tests := []struct {
+	for i, test := range []struct {
 		field     StructField
 		mustPanic bool
 		exported  bool
 	}{
 		{
-			field:    StructField{Name: "S1", Anonymous: true, Type: TypeOf(S1{})},
-			exported: true,
+			field:     StructField{Name: "", Type: TypeOf(S1{})},
+			mustPanic: false,
+			exported:  true,
 		},
 		{
-			field:    StructField{Name: "S1", Anonymous: true, Type: TypeOf((*S1)(nil))},
-			exported: true,
+			field:     StructField{Name: "", Type: TypeOf((*S1)(nil))},
+			mustPanic: false,
+			exported:  true,
 		},
 		{
-			field:     StructField{Name: "s2", Anonymous: true, Type: TypeOf(s2{})},
+			field:     StructField{Name: "", Type: TypeOf(s2{})},
+			mustPanic: false,
+			exported:  false,
+		},
+		{
+			field:     StructField{Name: "", Type: TypeOf((*s2)(nil))},
+			mustPanic: false,
+			exported:  false,
+		},
+		{
+			field:     StructField{Name: "", Type: TypeOf(S1{}), PkgPath: "other/pkg"},
 			mustPanic: true,
+			exported:  true,
 		},
 		{
-			field:     StructField{Name: "s2", Anonymous: true, Type: TypeOf((*s2)(nil))},
+			field:     StructField{Name: "", Type: TypeOf((*S1)(nil)), PkgPath: "other/pkg"},
 			mustPanic: true,
+			exported:  true,
 		},
 		{
-			field:     StructField{Name: "Name", Type: nil, PkgPath: ""},
+			field:     StructField{Name: "", Type: TypeOf(s2{}), PkgPath: "other/pkg"},
 			mustPanic: true,
+			exported:  false,
 		},
 		{
-			field:     StructField{Name: "", Type: TypeOf(S1{}), PkgPath: ""},
-			mustPanic: true,
-		},
-		{
-			field:     StructField{Name: "S1", Anonymous: true, Type: TypeOf(S1{}), PkgPath: "other/pkg"},
-			mustPanic: true,
-		},
-		{
-			field:     StructField{Name: "S1", Anonymous: true, Type: TypeOf((*S1)(nil)), PkgPath: "other/pkg"},
-			mustPanic: true,
-		},
-		{
-			field:     StructField{Name: "s2", Anonymous: true, Type: TypeOf(s2{}), PkgPath: "other/pkg"},
-			mustPanic: true,
-		},
-		{
-			field:     StructField{Name: "s2", Anonymous: true, Type: TypeOf((*s2)(nil)), PkgPath: "other/pkg"},
-			mustPanic: true,
-		},
-		{
-			field:     StructField{Name: "s2", Type: TypeOf(int(0)), PkgPath: "other/pkg"},
-			mustPanic: true,
-		},
-		{
-			field:     StructField{Name: "s2", Type: TypeOf(int(0)), PkgPath: "other/pkg"},
+			field:     StructField{Name: "", Type: TypeOf((*s2)(nil)), PkgPath: "other/pkg"},
 			mustPanic: true,
+			exported:  false,
 		},
 		{
 			field:     StructField{Name: "S", Type: TypeOf(S1{})},
@@ -4236,68 +4226,81 @@ func TestStructOfExportRules(t *testing.T) {
 			exported:  true,
 		},
 		{
-			field:    StructField{Name: "S", Type: TypeOf((*S1)(nil))},
-			exported: true,
+			field:     StructField{Name: "S", Type: TypeOf((*S1)(nil))},
+			mustPanic: false,
+			exported:  true,
 		},
 		{
-			field:    StructField{Name: "S", Type: TypeOf(s2{})},
-			exported: true,
+			field:     StructField{Name: "S", Type: TypeOf(s2{})},
+			mustPanic: false,
+			exported:  true,
 		},
 		{
-			field:    StructField{Name: "S", Type: TypeOf((*s2)(nil))},
-			exported: true,
+			field:     StructField{Name: "S", Type: TypeOf((*s2)(nil))},
+			mustPanic: false,
+			exported:  true,
 		},
 		{
 			field:     StructField{Name: "s", Type: TypeOf(S1{})},
 			mustPanic: true,
+			exported:  false,
 		},
 		{
 			field:     StructField{Name: "s", Type: TypeOf((*S1)(nil))},
 			mustPanic: true,
+			exported:  false,
 		},
 		{
 			field:     StructField{Name: "s", Type: TypeOf(s2{})},
 			mustPanic: true,
+			exported:  false,
 		},
 		{
 			field:     StructField{Name: "s", Type: TypeOf((*s2)(nil))},
 			mustPanic: true,
+			exported:  false,
 		},
 		{
 			field:     StructField{Name: "s", Type: TypeOf(S1{}), PkgPath: "other/pkg"},
 			mustPanic: true, // TODO(sbinet): creating a name with a package path
+			exported:  false,
 		},
 		{
 			field:     StructField{Name: "s", Type: TypeOf((*S1)(nil)), PkgPath: "other/pkg"},
 			mustPanic: true, // TODO(sbinet): creating a name with a package path
+			exported:  false,
 		},
 		{
 			field:     StructField{Name: "s", Type: TypeOf(s2{}), PkgPath: "other/pkg"},
 			mustPanic: true, // TODO(sbinet): creating a name with a package path
+			exported:  false,
 		},
 		{
 			field:     StructField{Name: "s", Type: TypeOf((*s2)(nil)), PkgPath: "other/pkg"},
 			mustPanic: true, // TODO(sbinet): creating a name with a package path
+			exported:  false,
 		},
 		{
 			field:     StructField{Name: "", Type: TypeOf(ΦType{})},
-			mustPanic: true,
+			mustPanic: false,
+			exported:  true,
 		},
 		{
 			field:     StructField{Name: "", Type: TypeOf(φType{})},
-			mustPanic: true,
+			mustPanic: false,
+			exported:  false,
 		},
 		{
-			field:    StructField{Name: "Φ", Type: TypeOf(0)},
-			exported: true,
+			field:     StructField{Name: "Φ", Type: TypeOf(0)},
+			mustPanic: false,
+			exported:  true,
 		},
 		{
-			field:    StructField{Name: "φ", Type: TypeOf(0)},
-			exported: false,
+			field:     StructField{Name: "φ", Type: TypeOf(0)},
+			mustPanic: false,
+			exported:  false,
 		},
-	}
-
-	for i, test := range tests {
+	} {
 		testPanic(i, test.mustPanic, func() {
 			typ := StructOf([]StructField{test.field})
 			if typ == nil {
@@ -4307,7 +4310,7 @@ func TestStructOfExportRules(t *testing.T) {
 			field := typ.Field(0)
 			n := field.Name
 			if n == "" {
-				panic("field.Name must not be empty")
+				n = field.Type.Name()
 			}
 			exported := isExported(n)
 			if exported != test.exported {
@@ -4385,7 +4388,7 @@ func TestStructOfGenericAlg(t *testing.T) {
 		{Name: "S1", Type: st1},
 	})
 
-	tests := []struct {
+	for _, table := range []struct {
 		rt  Type
 		idx []int
 	}{
@@ -4466,9 +4469,7 @@ func TestStructOfGenericAlg(t *testing.T) {
 			),
 			idx: []int{2},
 		},
-	}
-
-	for _, table := range tests {
+	} {
 		v1 := New(table.rt).Elem()
 		v2 := New(table.rt).Elem()
 
@@ -4570,21 +4571,18 @@ func TestStructOfWithInterface(t *testing.T) {
 	type Iface interface {
 		Get() int
 	}
-	tests := []struct {
-		name string
+	for i, table := range []struct {
 		typ  Type
 		val  Value
 		impl bool
 	}{
 		{
-			name: "StructI",
 			typ:  TypeOf(StructI(want)),
 			val:  ValueOf(StructI(want)),
 			impl: true,
 		},
 		{
-			name: "StructI",
-			typ:  PtrTo(TypeOf(StructI(want))),
+			typ: PtrTo(TypeOf(StructI(want))),
 			val: ValueOf(func() interface{} {
 				v := StructI(want)
 				return &v
@@ -4592,8 +4590,7 @@ func TestStructOfWithInterface(t *testing.T) {
 			impl: true,
 		},
 		{
-			name: "StructIPtr",
-			typ:  PtrTo(TypeOf(StructIPtr(want))),
+			typ: PtrTo(TypeOf(StructIPtr(want))),
 			val: ValueOf(func() interface{} {
 				v := StructIPtr(want)
 				return &v
@@ -4601,7 +4598,6 @@ func TestStructOfWithInterface(t *testing.T) {
 			impl: true,
 		},
 		{
-			name: "StructIPtr",
 			typ:  TypeOf(StructIPtr(want)),
 			val:  ValueOf(StructIPtr(want)),
 			impl: false,
@@ -4611,16 +4607,13 @@ func TestStructOfWithInterface(t *testing.T) {
 		//	val:  ValueOf(StructI(want)),
 		//	impl: true,
 		// },
-	}
-
-	for i, table := range tests {
+	} {
 		rt := StructOf(
 			[]StructField{
 				{
-					Name:      table.name,
-					Anonymous: true,
-					PkgPath:   "",
-					Type:      table.typ,
+					Name:    "",
+					PkgPath: "",
+					Type:    table.typ,
 				},
 			},
 		)
@@ -6066,7 +6059,6 @@ func TestSwapper(t *testing.T) {
 			want: []pairPtr{{5, 6, &c}, {3, 4, &b}, {1, 2, &a}},
 		},
 	}
-
 	for i, tt := range tests {
 		inStr := fmt.Sprint(tt.in)
 		Swapper(tt.in)(tt.i, tt.j)
@@ -6092,36 +6084,3 @@ func TestUnaddressableField(t *testing.T) {
 		lv.Set(rv)
 	})
 }
-
-type Tint int
-
-type Tint2 = Tint
-
-type Talias1 struct {
-	byte
-	uint8
-	int
-	int32
-	rune
-}
-
-type Talias2 struct {
-	Tint
-	Tint2
-}
-
-func TestAliasNames(t *testing.T) {
-	t1 := Talias1{byte: 1, uint8: 2, int: 3, int32: 4, rune: 5}
-	out := fmt.Sprintf("%#v", t1)
-	want := "reflect_test.Talias1{byte:0x1, uint8:0x2, int:3, int32:4, rune:5}"
-	if out != want {
-		t.Errorf("Talias1 print:\nhave: %s\nwant: %s", out, want)
-	}
-
-	t2 := Talias2{Tint: 1, Tint2: 2}
-	out = fmt.Sprintf("%#v", t2)
-	want = "reflect_test.Talias2{Tint:1, Tint2:2}"
-	if out != want {
-		t.Errorf("Talias2 print:\nhave: %s\nwant: %s", out, want)
-	}
-}

src/reflect/type.go

@@ -417,17 +417,9 @@ type sliceType struct {
 
 // Struct field
 type structField struct {
-	name       name    // name is always non-empty
-	typ        *rtype  // type of field
-	offsetAnon uintptr // byte offset of field<<1 | isAnonymous
-}
-
-func (f *structField) offset() uintptr {
-	return f.offsetAnon >> 1
-}
-
-func (f *structField) anon() bool {
-	return f.offsetAnon&1 != 0
+	name   name    // name is empty for embedded fields
+	typ    *rtype  // type of field
+	offset uintptr // byte offset of field within struct
 }
 
 // structType represents a struct type.
@@ -1223,8 +1215,16 @@ func (t *structType) Field(i int) (f StructField) {
 	}
 	p := &t.fields[i]
 	f.Type = toType(p.typ)
-	f.Name = p.name.name()
-	f.Anonymous = p.anon()
+	if name := p.name.name(); name != "" {
+		f.Name = name
+	} else {
+		t := f.Type
+		if t.Kind() == Ptr {
+			t = t.Elem()
+		}
+		f.Name = t.Name()
+		f.Anonymous = true
+	}
 	if !p.name.isExported() {
 		f.PkgPath = p.name.pkgPath()
 		if f.PkgPath == "" {
@@ -1234,7 +1234,7 @@ func (t *structType) Field(i int) (f StructField) {
 	if tag := p.name.tag(); tag != "" {
 		f.Tag = StructTag(tag)
 	}
-	f.Offset = p.offset()
+	f.Offset = p.offset
 
 	// NOTE(rsc): This is the only allocation in the interface
 	// presented by a reflect.Type. It would be nice to avoid,
@@ -1321,15 +1321,19 @@ func (t *structType) FieldByNameFunc(match func(string) bool) (result StructFiel
 			visited[t] = true
 			for i := range t.fields {
 				f := &t.fields[i]
-				// Find name and (for anonymous field) type for field f.
-				fname := f.name.name()
+				// Find name and type for field f.
+				var fname string
 				var ntyp *rtype
-				if f.anon() {
+				if name := f.name.name(); name != "" {
+					fname = name
+				} else {
 					// Anonymous field of type T or *T.
+					// Name taken from type.
 					ntyp = f.typ
 					if ntyp.Kind() == Ptr {
 						ntyp = ntyp.Elem().common()
 					}
+					fname = ntyp.Name()
 				}
 
 				// Does it match?
@@ -1386,11 +1390,13 @@ func (t *structType) FieldByName(name string) (f StructField, present bool) {
 	if name != "" {
 		for i := range t.fields {
 			tf := &t.fields[i]
-			if tf.name.name() == name {
-				return t.Field(i), true
-			}
-			if tf.anon() {
+			tfname := tf.name.name()
+			if tfname == "" {
 				hasAnon = true
+				continue
+			}
+			if tfname == name {
+				return t.Field(i), true
 			}
 		}
 	}
@@ -1689,7 +1695,7 @@ func haveIdenticalUnderlyingType(T, V *rtype, cmpTags bool) bool {
 			if cmpTags && tf.name.tag() != vf.name.tag() {
 				return false
 			}
-			if tf.offsetAnon != vf.offsetAnon {
+			if tf.offset != vf.offset {
 				return false
 			}
 			if !tf.name.isExported() {
@@ -2398,9 +2404,6 @@ func StructOf(fields []StructField) Type {
 	lastzero := uintptr(0)
 	repr = append(repr, "struct {"...)
 	for i, field := range fields {
-		if field.Name == "" {
-			panic("reflect.StructOf: field " + strconv.Itoa(i) + " has no name")
-		}
 		if field.Type == nil {
 			panic("reflect.StructOf: field " + strconv.Itoa(i) + " has no type")
 		}
@@ -2413,11 +2416,13 @@ func StructOf(fields []StructField) Type {
 			hasPtr = true
 		}
 
+		name := ""
 		// Update string and hash
-		name := f.name.name()
-		hash = fnv1(hash, []byte(name)...)
-		repr = append(repr, (" " + name)...)
-		if f.anon() {
+		if f.name.nameLen() > 0 {
+			hash = fnv1(hash, []byte(f.name.name())...)
+			repr = append(repr, (" " + f.name.name())...)
+			name = f.name.name()
+		} else {
 			// Embedded field
 			if f.typ.Kind() == Ptr {
 				// Embedded ** and *interface{} are illegal
@@ -2425,7 +2430,11 @@ func StructOf(fields []StructField) Type {
 				if k := elem.Kind(); k == Ptr || k == Interface {
 					panic("reflect.StructOf: illegal anonymous field type " + ft.String())
 				}
+				name = elem.String()
+			} else {
+				name = ft.String()
 			}
+			// TODO(sbinet) check for syntactically impossible type names?
 
 			switch f.typ.Kind() {
 			case Interface:
@@ -2557,12 +2566,11 @@ func StructOf(fields []StructField) Type {
 		comparable = comparable && (ft.alg.equal != nil)
 		hashable = hashable && (ft.alg.hash != nil)
 
-		offset := align(size, uintptr(ft.align))
+		f.offset = align(size, uintptr(ft.align))
 		if ft.align > typalign {
 			typalign = ft.align
 		}
-		size = offset + ft.size
-		f.offsetAnon |= offset << 1
+		size = f.offset + ft.size
 
 		if ft.size == 0 {
 			lastzero = size
@@ -2754,7 +2762,7 @@ func StructOf(fields []StructField) Type {
 		typ.alg.hash = func(p unsafe.Pointer, seed uintptr) uintptr {
 			o := seed
 			for _, ft := range typ.fields {
-				pi := unsafe.Pointer(uintptr(p) + ft.offset())
+				pi := unsafe.Pointer(uintptr(p) + ft.offset)
 				o = ft.typ.alg.hash(pi, o)
 			}
 			return o
@@ -2764,8 +2772,8 @@ func StructOf(fields []StructField) Type {
 	if comparable {
 		typ.alg.equal = func(p, q unsafe.Pointer) bool {
 			for _, ft := range typ.fields {
-				pi := unsafe.Pointer(uintptr(p) + ft.offset())
-				qi := unsafe.Pointer(uintptr(q) + ft.offset())
+				pi := unsafe.Pointer(uintptr(p) + ft.offset)
+				qi := unsafe.Pointer(uintptr(q) + ft.offset)
 				if !ft.typ.alg.equal(pi, qi) {
 					return false
 				}
@@ -2787,27 +2795,25 @@ func StructOf(fields []StructField) Type {
 }
 
 func runtimeStructField(field StructField) structField {
-	if field.PkgPath != "" {
-		panic("reflect.StructOf: StructOf does not allow unexported fields")
+	exported := field.PkgPath == ""
+	if field.Name == "" {
+		t := field.Type.(*rtype)
+		if t.Kind() == Ptr {
+			t = t.Elem().(*rtype)
+		}
+		exported = t.nameOff(t.str).isExported()
+	} else if exported {
+		b0 := field.Name[0]
+		if ('a' <= b0 && b0 <= 'z') || b0 == '_' {
+			panic("reflect.StructOf: field \"" + field.Name + "\" is unexported but has no PkgPath")
+		}
 	}
 
-	// Best-effort check for misuse.
-	// Since PkgPath is empty, not much harm done if Unicode lowercase slips through.
-	c := field.Name[0]
-	if 'a' <= c && c <= 'z' || c == '_' {
-		panic("reflect.StructOf: field \"" + field.Name + "\" is unexported but missing PkgPath")
-	}
-
-	offsetAnon := uintptr(0)
-	if field.Anonymous {
-		offsetAnon |= 1
-	}
-
-	resolveReflectType(field.Type.common()) // install in runtime
+	_ = resolveReflectType(field.Type.common())
 	return structField{
-		name:       newName(field.Name, string(field.Tag), "", true),
-		typ:        field.Type.common(),
-		offsetAnon: offsetAnon,
+		name:   newName(field.Name, string(field.Tag), field.PkgPath, exported),
+		typ:    field.Type.common(),
+		offset: 0,
 	}
 }
 
@@ -2830,7 +2836,7 @@ func typeptrdata(t *rtype) uintptr {
 			}
 		}
 		f := st.fields[field]
-		return f.offset() + f.typ.ptrdata
+		return f.offset + f.typ.ptrdata
 
 	default:
 		panic("reflect.typeptrdata: unexpected type, " + t.String())
@@ -3204,7 +3210,7 @@ func addTypeBits(bv *bitVector, offset uintptr, t *rtype) {
 		tt := (*structType)(unsafe.Pointer(t))
 		for i := range tt.fields {
 			f := &tt.fields[i]
-			addTypeBits(bv, offset+f.offset(), f.typ)
+			addTypeBits(bv, offset+f.offset, f.typ)
 		}
 	}
 }

src/reflect/value.go

@@ -769,7 +769,7 @@ func (v Value) Field(i int) Value {
 	fl := v.flag&(flagStickyRO|flagIndir|flagAddr) | flag(typ.Kind())
 	// Using an unexported field forces flagRO.
 	if !field.name.isExported() {
-		if field.anon() {
+		if field.name.name() == "" {
 			fl |= flagEmbedRO
 		} else {
 			fl |= flagStickyRO
@@ -780,7 +780,7 @@ func (v Value) Field(i int) Value {
 	// In the former case, we want v.ptr + offset.
 	// In the latter case, we must have field.offset = 0,
 	// so v.ptr + field.offset is still okay.
-	ptr := unsafe.Pointer(uintptr(v.ptr) + field.offset())
+	ptr := unsafe.Pointer(uintptr(v.ptr) + field.offset)
 	return Value{typ, ptr, fl}
 }