go/types, types2: better error message for invalid method expression

Fixes #53358.

Change-Id: I38528da1596b6e1aaedcab89b1513fb8acac596c
Reviewed-on: https://go-review.googlesource.com/c/go/+/455335
Reviewed-by: Robert Findley <rfindley@google.com>
Auto-Submit: Robert Griesemer <gri@google.com>
Run-TryBot: Robert Griesemer <gri@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@google.com>

5 files changed, 33 insertions, 6 deletions

diff --git a/src/cmd/compile/internal/types2/call.go b/src/cmd/compile/internal/types2/call.go
index ffff11ea6e..50343bf77a 100644
--- a/src/cmd/compile/internal/types2/call.go
+++ b/src/cmd/compile/internal/types2/call.go
@@ -573,7 +573,11 @@ func (check *Checker) selector(x *operand, e *syntax.SelectorExpr, def *Named) {
 		}
 
 		if indirect {
-			check.errorf(e.Sel, InvalidMethodExpr, "cannot call pointer method %s on %s", sel, x.typ)
+			if x.mode == typexpr {
+				check.errorf(e.Sel, InvalidMethodExpr, "invalid method expression %s.%s (needs pointer receiver (*%s).%s)", x.typ, sel, x.typ, sel)
+			} else {
+				check.errorf(e.Sel, InvalidMethodExpr, "cannot call pointer method %s on %s", sel, x.typ)
+			}
 			goto Error
 		}
 
diff --git a/src/go/types/call.go b/src/go/types/call.go
index 7a9329613d..5558244f1b 100644
--- a/src/go/types/call.go
+++ b/src/go/types/call.go
@@ -577,7 +577,11 @@ func (check *Checker) selector(x *operand, e *ast.SelectorExpr, def *Named) {
 		}
 
 		if indirect {
-			check.errorf(e.Sel, InvalidMethodExpr, "cannot call pointer method %s on %s", sel, x.typ)
+			if x.mode == typexpr {
+				check.errorf(e.Sel, InvalidMethodExpr, "invalid method expression %s.%s (needs pointer receiver (*%s).%s)", x.typ, sel, x.typ, sel)
+			} else {
+				check.errorf(e.Sel, InvalidMethodExpr, "cannot call pointer method %s on %s", sel, x.typ)
+			}
 			goto Error
 		}
 
diff --git a/src/internal/types/testdata/check/expr3.go b/src/internal/types/testdata/check/expr3.go
index 2ca39866fc..2da59841c6 100644
--- a/src/internal/types/testdata/check/expr3.go
+++ b/src/internal/types/testdata/check/expr3.go
@@ -157,10 +157,10 @@ func (*T) m() {}
 func method_expressions() {
 	_ = T.a /* ERROR "no field or method" */
 	_ = T.x /* ERROR "has no method" */
-	_ = T.m /* ERROR "cannot call pointer method m on T" */
+	_ = T.m /* ERROR "invalid method expression T\.m \(needs pointer receiver \(\*T\)\.m\)" */
 	_ = (*T).m
 
-	var f func(*T) = T.m /* ERROR "cannot call pointer method m on T" */
+	var f func(*T) = T.m /* ERROR "invalid method expression T\.m \(needs pointer receiver \(\*T\)\.m\)" */
 	var g func(*T) = (*T).m
 	_, _ = f, g
 
diff --git a/src/internal/types/testdata/check/methodsets.go b/src/internal/types/testdata/check/methodsets.go
index b0eb14cf50..d145bc09f5 100644
--- a/src/internal/types/testdata/check/methodsets.go
+++ b/src/internal/types/testdata/check/methodsets.go
@@ -29,7 +29,7 @@ type T3 struct {
 func _() {
 	var (
 		_ func(T0) = T0.v0
-		_ = T0.p0 /* ERROR "cannot call pointer method p0 on T0" */
+		_ = T0.p0 /* ERROR invalid method expression T0\.p0 \(needs pointer receiver \(\*T0\)\.p0\) */
 
 		_ func (*T0) = (*T0).v0
 		_ func (*T0) = (*T0).p0
@@ -40,7 +40,7 @@ func _() {
 		_ func(T2) = T2.p2
 
 		_ func(T3) = T3.v0
-		_ func(T3) = T3.p0 /* ERROR "cannot call pointer method p0 on T3" */
+		_ func(T3) = T3.p0 /* ERROR invalid method expression T3\.p0 \(needs pointer receiver \(\*T3\)\.p0\) */
 		_ func(T3) = T3.v1
 		_ func(T3) = T3.p1
 		_ func(T3) = T3.v2
diff --git a/src/internal/types/testdata/fixedbugs/issue53358.go b/src/internal/types/testdata/fixedbugs/issue53358.go
new file mode 100644
index 0000000000..774136f4f7
--- /dev/null
+++ b/src/internal/types/testdata/fixedbugs/issue53358.go
@@ -0,0 +1,19 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package p
+
+type A struct{}
+
+func (*A) m() int { return 0 }
+
+var _ = A.m /* ERROR invalid method expression A\.m \(needs pointer receiver \(\*A\)\.m\) */ ()
+var _ = (*A).m(nil)
+
+type B struct{ A }
+
+var _ = B.m // ERROR invalid method expression B\.m \(needs pointer receiver \(\*B\)\.m\)
+var _ = (*B).m
+
+var _ = struct{ A }.m // ERROR invalid method expression struct{A}\.m \(needs pointer receiver \(\*struct{A}\)\.m\)