test: test method expressions with parameters, and with import

The gccgo compiler had two different bugs triggered by this
test case.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5606052

test/method4.go

+// $G $D/method4a.go && $G $D/$F.go && $L $F.$A && ./$A.out
+
+// Copyright 2012 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.
+
+// Test method expressions with arguments.
+
+package main
+
+import "./method4a"
+
+type T1 int
+
+type T2 struct {
+	f int
+}
+
+type I1 interface {
+	Sum([]int, int) int
+}
+
+type I2 interface {
+	Sum(a []int, b int) int
+}
+
+func (i T1) Sum(a []int, b int) int {
+	r := int(i) + b
+	for _, v := range a {
+		r += v
+	}
+	return r
+}
+
+func (p *T2) Sum(a []int, b int) int {
+	r := p.f + b
+	for _, v := range a {
+		r += v
+	}
+	return r
+}
+
+func eq(v1, v2 int) {
+	if v1 != v2 {
+		panic(0)
+	}
+}
+
+func main() {
+	a := []int{1, 2, 3}
+	t1 := T1(4)
+	t2 := &T2{4}
+
+	eq(t1.Sum(a, 5), 15)
+	eq(t2.Sum(a, 6), 16)
+
+	eq(T1.Sum(t1, a, 7), 17)
+	eq((*T2).Sum(t2, a, 8), 18)
+
+	f1 := T1.Sum
+	eq(f1(t1, a, 9), 19)
+	f2 := (*T2).Sum
+	eq(f2(t2, a, 10), 20)
+
+	eq(I1.Sum(t1, a, 11), 21)
+	eq(I1.Sum(t2, a, 12), 22)
+
+	f3 := I1.Sum
+	eq(f3(t1, a, 13), 23)
+	eq(f3(t2, a, 14), 24)
+
+	eq(I2.Sum(t1, a, 15), 25)
+	eq(I2.Sum(t2, a, 16), 26)
+
+	f4 := I2.Sum
+	eq(f4(t1, a, 17), 27)
+	eq(f4(t2, a, 18), 28)
+	
+	mt1 := method4a.T1(4)
+	mt2 := &method4a.T2{4}
+
+	eq(mt1.Sum(a, 30), 40)
+	eq(mt2.Sum(a, 31), 41)
+
+	eq(method4a.T1.Sum(mt1, a, 32), 42)
+	eq((*method4a.T2).Sum(mt2, a, 33), 43)
+
+	g1 := method4a.T1.Sum
+	eq(g1(mt1, a, 34), 44)
+	g2 := (*method4a.T2).Sum
+	eq(g2(mt2, a, 35), 45)
+
+	eq(method4a.I1.Sum(mt1, a, 36), 46)
+	eq(method4a.I1.Sum(mt2, a, 37), 47)
+
+	g3 := method4a.I1.Sum
+	eq(g3(mt1, a, 38), 48)
+	eq(g3(mt2, a, 39), 49)
+
+	eq(method4a.I2.Sum(mt1, a, 40), 50)
+	eq(method4a.I2.Sum(mt2, a, 41), 51)
+
+	g4 := method4a.I2.Sum
+	eq(g4(mt1, a, 42), 52)
+	eq(g4(mt2, a, 43), 53)
+}

test/method4a.go

+// true
+
+// Copyright 2012 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.
+
+// Test method expressions with arguments.
+// This file is not tested by itself; it is imported by method4.go.
+
+package method4a
+
+type T1 int
+
+type T2 struct {
+	F int
+}
+
+type I1 interface {
+	Sum([]int, int) int
+}
+
+type I2 interface {
+	Sum(a []int, b int) int
+}
+
+func (i T1) Sum(a []int, b int) int {
+	r := int(i) + b
+	for _, v := range a {
+		r += v
+	}
+	return r
+}
+
+func (p *T2) Sum(a []int, b int) int {
+	r := p.F + b
+	for _, v := range a {
+		r += v
+	}
+	return r
+}