cmd/compile: emit error message for broken type

The original report in #5172 was that cmd/compile was generating bogus
follow-on error messages when typechecking a struct failed. Instead of
fixing those follow-on error messages, golang.org/cl/9614044 suppress all
follow-on error messages after struct typecheck fails. We should
continue emitting error messages instead.

While at it, also add the test case for original report.

Fixes #33947

Change-Id: I4a5c6878977128abccd704350a12df743631c7bf
Reviewed-on: https://go-review.googlesource.com/c/go/+/191944
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

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

@@ -503,12 +503,7 @@ func typecheck1(n *Node, top int) (res *Node) {
 
 	case OTSTRUCT:
 		ok |= Etype
-		t := tostruct(n.List.Slice())
-		if t.Broke() {
-			n.Type = nil
-			return n
-		}
-		setTypeNode(n, t)
+		setTypeNode(n, tostruct(n.List.Slice()))
 		n.List.Set(nil)
 
 	case OTINTER:

test/fixedbugs/issue5172.go

@@ -12,8 +12,15 @@ type foo struct {
 	x bar // ERROR "undefined"
 }
 
+type T struct{}
+
+func (t T) Bar() {}
+
 func main() {
 	var f foo
-	go f.bar()	// GCCGO_ERROR "undefined"
-	defer f.bar()	// GCCGO_ERROR "undefined"
+	go f.bar()    // ERROR "undefined"
+	defer f.bar() // ERROR "undefined"
+
+	t := T{1} // ERROR "too many values"
+	go t.Bar()
 }