go/test/cmp1.go

// $G $D/$F.go && $L $F.$A && ./$A.out

// Copyright 2009 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 main

import "unsafe"

func use(bool) { }

func stringptr(s string) uintptr {
	return *(&s).(unsafe.Pointer).(*uintptr);
}

func isfalse(b bool) {
	if b { panicln("wanted false, got true") } // stack will explain where
}

func istrue(b bool) {
	if !b { panicln("wanted true, got false") } // stack will explain where
}

func main()
{
	var a []int;
	var b map[string]int;

	var c string = "hello";
	var d string = "hel";	// try to get different pointer
	d = d + "lo";
	if stringptr(c) == stringptr(d) {
		panic("compiler too smart -- got same string")
	}

	var e = make(chan int);

	var ia interface{} = a;
	var ib interface{} = b;
	var ic interface{} = c;
	var id interface{} = d;
	var ie interface{} = e;

	// these comparisons are okay because
	// string compare is okay and the others
	// are comparisons where the types differ.
	isfalse(ia == ib);
	isfalse(ia == ic);
	isfalse(ia == id);
	isfalse(ib == ic);
	isfalse(ib == id);
	istrue(ic == id);
	istrue(ie == ie);

	// map of interface should use == on interface values,
	// not memory.
	// TODO: should m[c], m[d] be valid here?
	var m = make(map[interface{}] int);
	m[ic] = 1;
	m[id] = 2;
	if m[ic] != 2 {
		panic("m[ic] = ", m[ic]);
	}
}