From: Alan Donovan <adonovan@google.com>
Date: Fri, 28 Oct 2022 20:16:56 +0000 (-0400)
Subject: go/types: avoid formatting unneeded causes
X-Git-Tag: go1.20rc1~498
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=4b993bffb83394105d13b426dae12afe0ab05804;p=gostls13.git

go/types: avoid formatting unneeded causes

This one slipped through a previous cleanup
and showed up in an allocation profile.

Change-Id: Ife447fe32797f1685c20806718193b0985b4a412
Reviewed-on: https://go-review.googlesource.com/c/go/+/446295
Reviewed-by: Robert Findley <rfindley@google.com>
Run-TryBot: Alan Donovan <adonovan@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
---

diff --git a/src/cmd/compile/internal/types2/instantiate.go b/src/cmd/compile/internal/types2/instantiate.go
index 55ab7a8d25..ff8b70f8a2 100644
--- a/src/cmd/compile/internal/types2/instantiate.go
+++ b/src/cmd/compile/internal/types2/instantiate.go
@@ -201,13 +201,13 @@ func (check *Checker) implements(V, T Type, constraint bool, cause *string) bool
 
 	Ti, _ := Tu.(*Interface)
 	if Ti == nil {
-		var detail string
-		if isInterfacePtr(Tu) {
-			detail = check.sprintf("type %s is pointer to interface, not interface", T)
-		} else {
-			detail = check.sprintf("%s is not an interface", T)
-		}
 		if cause != nil {
+			var detail string
+			if isInterfacePtr(Tu) {
+				detail = check.sprintf("type %s is pointer to interface, not interface", T)
+			} else {
+				detail = check.sprintf("%s is not an interface", T)
+			}
 			*cause = check.sprintf("%s does not implement %s (%s)", V, T, detail)
 		}
 		return false
diff --git a/src/go/types/instantiate.go b/src/go/types/instantiate.go
index 24a9f280b0..3b50c6ce33 100644
--- a/src/go/types/instantiate.go
+++ b/src/go/types/instantiate.go
@@ -201,13 +201,13 @@ func (check *Checker) implements(V, T Type, constraint bool, cause *string) bool
 
 	Ti, _ := Tu.(*Interface)
 	if Ti == nil {
-		var detail string
-		if isInterfacePtr(Tu) {
-			detail = check.sprintf("type %s is pointer to interface, not interface", T)
-		} else {
-			detail = check.sprintf("%s is not an interface", T)
-		}
 		if cause != nil {
+			var detail string
+			if isInterfacePtr(Tu) {
+				detail = check.sprintf("type %s is pointer to interface, not interface", T)
+			} else {
+				detail = check.sprintf("%s is not an interface", T)
+			}
 			*cause = check.sprintf("%s does not implement %s (%s)", V, T, detail)
 		}
 		return false