cmd/compile: lookup methods of base type for named pointer type

Passed toolstash-check.

Updates #21738
Fixes #21934

Change-Id: I59f0b2c9890146565ff913b04aeeeff7dc7a4499
Reviewed-on: https://go-review.googlesource.com/c/go/+/197561
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

diff --git a/src/cmd/compile/internal/gc/subr.go b/src/cmd/compile/internal/gc/subr.go
index 3fc59194e412cd81aa36c30afe1a43f5b04e646c..27326f67a1143674bfbd2f341f0b4284fad20f70 100644 (file)
--- a/src/cmd/compile/internal/gc/subr.go
+++ b/src/cmd/compile/internal/gc/subr.go
@@ -1189,7 +1189,12 @@ func lookdot0(s *types.Sym, t *types.Type, save **types.Field, ignorecase bool)
                }
        }
 
-       u = methtype(t)
+       u = t
+       if t.Sym != nil && t.IsPtr() && !t.Elem().IsPtr() {
+               // If t is a defined pointer type, then x.m is shorthand for (*x).m.
+               u = t.Elem()
+       }
+       u = methtype(u)
        if u != nil {
                for _, f := range u.Methods().Slice() {
                        if f.Embedded == 0 && (f.Sym == s || (ignorecase && strings.EqualFold(f.Sym.Name, s.Name))) {

diff --git a/test/fixedbugs/issue21934.go b/test/fixedbugs/issue21934.go
new file mode 100644 (file)
index 0000000..e9a430f
--- /dev/null
+++ b/test/fixedbugs/issue21934.go
@@ -0,0 +1,26 @@
+// errorcheck
+
+// Copyright 2019 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.
+
+// selector expression resolves incorrectly for defined
+// pointer types.
+
+package main
+
+type E struct{ f int }
+type T struct{ E }
+
+func (*T) f() int { return 0 }
+
+type P *T
+type PP **T
+
+func main() {
+       var x P
+       _ = x.f // ERROR "x\.f undefined \(type P has no field or method f\)"
+
+       var y PP
+       _ = y.f // ERROR "y\.f undefined \(type PP has no field or method f\)"
+}