runtime: do not print recovered when double panic with the same value

Show the "[recovered, repanicked]" message only when it is repanicked
after recovered. For the duplicated panics that not recovered, do not
show this message.

Fixes #76099

Change-Id: I87282022ebe44c6f6efbe3239218be4a2a7b1104
Reviewed-on: https://go-review.googlesource.com/c/go/+/716020
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Junyang Shao <shaojunyang@google.com>
Auto-Submit: Michael Pratt <mpratt@google.com>

src/runtime/crash_test.go

@@ -413,6 +413,15 @@ func TestRepanickedPanicSandwich(t *testing.T) {
 	}
 }
 
+func TestDoublePanicWithSameValue(t *testing.T) {
+	output := runTestProg(t, "testprog", "DoublePanicWithSameValue")
+	want := `panic: message
+`
+	if !strings.HasPrefix(output, want) {
+		t.Fatalf("output does not start with %q:\n%s", want, output)
+	}
+}
+
 func TestGoexitCrash(t *testing.T) {
 	// External linking brings in cgo, causing deadlock detection not working.
 	testenv.MustInternalLink(t, deadlockBuildTypes)

src/runtime/panic.go

@@ -739,7 +739,7 @@ func printpanics(p *_panic) {
 	}
 	print("panic: ")
 	printpanicval(p.arg)
-	if p.repanicked {
+	if p.recovered && p.repanicked {
 		print(" [recovered, repanicked]")
 	} else if p.recovered {
 		print(" [recovered]")

src/runtime/testdata/testprog/crash.go

@@ -22,6 +22,7 @@ func init() {
 	register("RepanickedPanic", RepanickedPanic)
 	register("RepanickedMiddlePanic", RepanickedMiddlePanic)
 	register("RepanickedPanicSandwich", RepanickedPanicSandwich)
+	register("DoublePanicWithSameValue", DoublePanicWithSameValue)
 }
 
 func test(name string) {
@@ -189,3 +190,13 @@ func RepanickedPanicSandwich() {
 		panic("outer")
 	}()
 }
+
+// Double panic with same value and not recovered.
+// See issue 76099.
+func DoublePanicWithSameValue() {
+	var e any = "message"
+	defer func() {
+		panic(e)
+	}()
+	panic(e)
+}