runtime: symbolize wrappers as a last resort in race tracebacks

CL 466099 rewrote stack symbolization in race reports. Prior to this
CL, physical frames consisting entirely of wrapper logical frame would
print the wrapper, even though in other cases we try to avoid
printing wrappers. CL 466099 unintentionally changed this behavior and
now physical frames consisting entirely of wrapper frames instead fail
to symbolize and print "??()".

Fix this by taking the outermost wrapper frame if the entire logical
frame expansion consists of wrappers.

Fixes #60245.

Change-Id: I13de8857e508b757ea10d1fc7a47258d7fddbfdb
Reviewed-on: https://go-review.googlesource.com/c/go/+/497235
Reviewed-by: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
Auto-Submit: Austin Clements <austin@google.com>

src/runtime/race.go

@@ -175,8 +175,11 @@ func raceSymbolizeCode(ctx *symbolizeCodeContext) {
 		u, uf := newInlineUnwinder(fi, pc, nil)
 		for ; uf.valid(); uf = u.next(uf) {
 			sf := u.srcFunc(uf)
-			if sf.funcID == abi.FuncIDWrapper {
-				// ignore wrappers
+			if sf.funcID == abi.FuncIDWrapper && u.isInlined(uf) {
+				// Ignore wrappers, unless we're at the outermost frame of u.
+				// A non-inlined wrapper frame always means we have a physical
+				// frame consisting entirely of wrappers, in which case we'll
+				// take a outermost wrapper over nothing.
 				continue
 			}
 

src/runtime/race/output_test.go

@@ -439,4 +439,42 @@ Goroutine [0-9] \(running\) created at:
   main\.main\(\)
       .*/main.go:[0-9]+ \+0x[0-9,a-f]+
 ==================`}},
+	// Test symbolizing wrappers. Both (*T).f and main.func1 are wrappers.
+	// go.dev/issue/60245
+	{"wrappersym", "run", "", "atexit_sleep_ms=0", `
+package main
+import "sync"
+var wg sync.WaitGroup
+var x int
+func main() {
+	f := (*T).f
+	wg.Add(2)
+	go f(new(T))
+	f(new(T))
+	wg.Wait()
+}
+type T struct{}
+func (t T) f() {
+	x = 42
+	wg.Done()
+}
+`, []string{`==================
+WARNING: DATA RACE
+Write at 0x[0-9,a-f]+ by goroutine [0-9]:
+  main\.T\.f\(\)
+      .*/main.go:15 \+0x[0-9,a-f]+
+  main\.\(\*T\)\.f\(\)
+      <autogenerated>:1 \+0x[0-9,a-f]+
+  main\.main\.func1\(\)
+      .*/main.go:9 \+0x[0-9,a-f]+
+
+Previous write at 0x[0-9,a-f]+ by main goroutine:
+  main\.T\.f\(\)
+      .*/main.go:15 \+0x[0-9,a-f]+
+  main\.\(\*T\)\.f\(\)
+      <autogenerated>:1 \+0x[0-9,a-f]+
+  main\.main\(\)
+      .*/main.go:10 \+0x[0-9,a-f]+
+
+`}},
 }