bug285: assignment compatible map keys must be accepted

R=r
CC=golang-dev
https://golang.org/cl/1473042

test/bugs/bug285.go

+// $G $D/$F.go || echo BUG: should compile
+
+// Copyright 2010 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 for issue 778: Map key values that are assignment
+// compatible with the map key type must be accepted according
+// to the spec: http://golang.org/doc/go_spec.html#Indexes .
+
+package main
+
+type T2 struct {
+	x int
+}
+
+func (t *T2) f() int { return t.x }
+
+func main() {
+	type B bool
+	b := B(false)
+	mb := make(map[B]int)
+	mb[false] = 42 // this should work: false is assignment compatible with B
+	mb[b] = 42
+
+	type Z int
+	z := Z(0)
+	mz := make(map[Z]int)
+	mz[0] = 42
+	mz[z] = 42
+
+	type S string
+	s := S("foo")
+	ms := make(map[S]int)
+	ms["foo"] = 42
+	ms[s] = 42
+
+	type T struct {
+		x int
+	}
+	type P *T
+	p := P(nil)
+	mp := make(map[P]int)
+	mp[nil] = 42
+	mp[p] = 42
+	mp[&T{7}] = 42
+
+	type F func(x int)
+	f := func(x int) {}
+	mf := make(map[F]int)
+	mf[nil] = 42
+	mf[f] = 42
+	mf[func(x int) {}] = 42
+
+	type M map[int]int
+	m := make(M)
+	mm := make(map[M]int)
+	mm[nil] = 42
+	mm[m] = 42
+	mm[make(M)] = 42
+
+	type C chan int
+	c := make(C)
+	mc := make(map[C]int)
+	mc[nil] = 42
+	mc[c] = 42
+	mc[make(C)] = 42
+
+	type I1 interface{}
+	type I2 interface {
+		f() int
+	}
+	var i0 interface{} = z
+	var i1 I1 = p
+	m0 := make(map[interface{}]int)
+	m1 := make(map[I1]int)
+	m2 := make(map[I2]int)
+	m0[i0] = 42
+	m0[i1] = 42
+	m0[z] = 42 // this should work: z is assignment-compatible with interface{}
+	m0[new(struct {
+		x int
+	})] = 42       // this should work: *struct{x int} is assignment-compatible with interface{}
+	m0[p] = 42     // this should work: p is assignment-compatible with interface{}
+	m0[false] = 42 // this should work: false is assignment-compatible with interface{}
+	m0[17] = 42    // this should work: 17 is assignment-compatible with interface{}
+	m0["foo"] = 42 // this should work: "foo" is assignment-compatible with interface{}
+
+	m1[i0] = 42
+	m1[i1] = 42
+	m1[new(struct {
+		x int
+	})] = 42       // this should work: *struct{x int} is assignment-compatible with I1
+	m1[false] = 42 // this should work: false is assignment-compatible with I1
+	m1[17] = 42    // this should work: 17 is assignment-compatible with I1
+	m1["foo"] = 42 // this should work: "foo" is assignment-compatible with I1
+
+	var t2 T2
+	m2[new(T2)] = 42 // this should work: *T2 is assignment-compatible with I2
+	m2[t2] = 42      // this should work: t2 is assignment-compatible with I2
+}
+
+/*
+6g -e bug286.go
+bug286.go:23: invalid map index false - need type B
+bug286.go:80: invalid map index z - need type interface { }
+bug286.go:83: invalid map index new(struct { x int }) - need type interface { }
+bug286.go:84: invalid map index p - need type interface { }
+bug286.go:85: invalid map index false - need type interface { }
+bug286.go:86: invalid map index 17 - need type interface { }
+bug286.go:87: invalid map index "foo" - need type interface { }
+bug286.go:93: invalid map index new(struct { x int }) - need type I1
+bug286.go:94: invalid map index false - need type I1
+bug286.go:95: invalid map index 17 - need type I1
+bug286.go:96: invalid map index "foo" - need type I1
+bug286.go:99: invalid map index new(T2) - need type I2
+bug286.go:100: invalid map index t2 - need type I2
+*/

test/golden.out

@@ -220,3 +220,17 @@ errchk: bugs/bug284.go: unmatched error messages:
 ==================================================
 bugs/bug284.go:186: internal compiler error: typename ideal
 ==================================================
+
+=========== bugs/bug285.go
+bugs/bug285.go:23: invalid map index false - need type B
+bugs/bug285.go:80: invalid map index z - need type interface { }
+bugs/bug285.go:83: invalid map index new(struct { x int }) - need type interface { }
+bugs/bug285.go:84: invalid map index p - need type interface { }
+bugs/bug285.go:85: invalid map index false - need type interface { }
+bugs/bug285.go:86: invalid map index 17 - need type interface { }
+bugs/bug285.go:87: invalid map index "foo" - need type interface { }
+bugs/bug285.go:93: invalid map index new(struct { x int }) - need type I1
+bugs/bug285.go:94: invalid map index false - need type I1
+bugs/bug285.go:95: invalid map index 17 - need type I1
+bugs/bug285.go:95: too many errors
+BUG: should compile