go/types, types2: slightly better tracing output (debugging support)

Change-Id: I48804eba94ec455c4764d52af148f4210faf7d94
Reviewed-on: https://go-review.googlesource.com/c/go/+/379836
Trust: Robert Griesemer <[email protected]>
Run-TryBot: Robert Griesemer <[email protected]>
Reviewed-by: Robert Findley <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>

Author: griesemer

src/cmd/compile/internal/types2/decl.go

@@ -278,7 +278,9 @@ loop:
 			check.trace(obj.Pos(), "## cycle contains: %d values, %d type definitions", nval, ndef)
 		}
 		defer func() {
-			if !valid {
+			if valid {
+				check.trace(obj.Pos(), "=> cycle is valid")
+			} else {
 				check.trace(obj.Pos(), "=> error: cycle is invalid")
 			}
 		}()

src/cmd/compile/internal/types2/typexpr.go

@@ -211,7 +211,7 @@ func goTypeName(typ Type) string {
 //
 func (check *Checker) typInternal(e0 syntax.Expr, def *Named) (T Type) {
 	if check.conf.Trace {
-		check.trace(e0.Pos(), "type %s", e0)
+		check.trace(e0.Pos(), "-- type %s", e0)
 		check.indent++
 		defer func() {
 			check.indent--

src/go/types/decl.go

@@ -277,7 +277,9 @@ loop:
 			check.trace(obj.Pos(), "## cycle contains: %d values, %d type definitions", nval, ndef)
 		}
 		defer func() {
-			if !valid {
+			if valid {
+				check.trace(obj.Pos(), "=> cycle is valid")
+			} else {
 				check.trace(obj.Pos(), "=> error: cycle is invalid")
 			}
 		}()

src/go/types/typexpr.go

@@ -209,7 +209,7 @@ func goTypeName(typ Type) string {
 //
 func (check *Checker) typInternal(e0 ast.Expr, def *Named) (T Type) {
 	if trace {
-		check.trace(e0.Pos(), "type %s", e0)
+		check.trace(e0.Pos(), "-- type %s", e0)
 		check.indent++
 		defer func() {
 			check.indent--