cmd/compile: fix importing of method expressions

For OMETHEXPR, the Name in the Selection needs to be properly
linked up to the method declaration. Use the same code we
already have for ODOTMETH and OCALLPART to do that.

Fixes #45503

Change-Id: I7d6f886d606bae6faad8c104f50c177f871d41c8
Reviewed-on: https://go-review.googlesource.com/c/go/+/309831
Trust: Keith Randall <khr@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Dan Scales <danscales@google.com>

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

@@ -1591,17 +1591,10 @@ func (w *exportWriter) expr(n ir.Node) {
 		w.exoticSelector(n.Sel)
 		if go117ExportTypes {
 			w.exoticType(n.Type())
-			if n.Op() == ir.ODOT || n.Op() == ir.ODOTPTR || n.Op() == ir.ODOTINTER || n.Op() == ir.OMETHEXPR {
+			if n.Op() == ir.ODOT || n.Op() == ir.ODOTPTR || n.Op() == ir.ODOTINTER {
 				w.exoticParam(n.Selection)
-				if n.Op() == ir.OMETHEXPR {
-					name := ir.MethodExprName(n)
-					w.bool(name != nil)
-					if name != nil {
-						w.exoticType(name.Type())
-					}
-				}
 			}
-			// n.Selection is not required for ODOTMETH and OCALLPART. It will
+			// n.Selection is not required for OMETHEXPR, ODOTMETH, and OCALLPART. It will
 			// be reconstructed during import.
 		}
 

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

@@ -1197,23 +1197,17 @@ func (r *importReader) node() ir.Node {
 		pos := r.pos()
 		expr := r.expr()
 		sel := r.exoticSelector()
-		n := ir.NewSelectorExpr(pos, ir.OXDOT, expr, sel)
-		n.SetOp(op)
+		n := ir.NewSelectorExpr(pos, op, expr, sel)
 		n.SetType(r.exoticType())
 		switch op {
-		case ir.ODOT, ir.ODOTPTR, ir.ODOTINTER, ir.OMETHEXPR:
+		case ir.ODOT, ir.ODOTPTR, ir.ODOTINTER:
 			n.Selection = r.exoticParam()
-			if op == ir.OMETHEXPR {
-				if r.bool() { // has name
-					ir.MethodExprName(n).SetType(r.exoticType())
-				}
-			}
-		case ir.ODOTMETH, ir.OCALLPART:
+		case ir.ODOTMETH, ir.OCALLPART, ir.OMETHEXPR:
 			// These require a Lookup to link to the correct declaration.
 			rcvrType := expr.Type()
 			typ := n.Type()
 			n.Selection = Lookdot(n, rcvrType, 1)
-			if op == ir.OCALLPART {
+			if op == ir.OCALLPART || op == ir.OMETHEXPR {
 				// Lookdot clobbers the opcode and type, undo that.
 				n.SetOp(op)
 				n.SetType(typ)

test/fixedbugs/issue45503.dir/a.go

@@ -0,0 +1,15 @@
+// Copyright 2021 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 a
+
+type S struct{}
+
+func (s *S) M() {
+	s.m((*S).N)
+}
+
+func (s *S) N() {}
+
+func (s *S) m(func(*S)) {}

test/fixedbugs/issue45503.dir/b.go

@@ -0,0 +1,12 @@
+// Copyright 2021 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 b
+
+import "a"
+
+func F() {
+	s := a.S{}
+	s.M()
+}

test/fixedbugs/issue45503.go

@@ -0,0 +1,10 @@
+// compiledir
+
+// Copyright 2021 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.
+
+// This test exercises exporting + importing method
+// expressions for use when inlining.
+
+package ignored