From 39ad208c13368bbd1a129c5e2ed85d6ebc22401a Mon Sep 17 00:00:00 2001 From: Brad Fitzpatrick Date: Tue, 12 Jun 2018 16:16:38 +0000 Subject: test: add test to verify that string copies don't get optimized away Fixes #25834 Change-Id: I33e58dabfd04b84dfee1a9a3796796b5d19862e7 Reviewed-on: https://go-review.googlesource.com/118295 Run-TryBot: Brad Fitzpatrick TryBot-Result: Gobot Gobot Reviewed-by: Ian Lance Taylor --- test/strcopy.go | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) create mode 100644 test/strcopy.go (limited to 'test/strcopy.go') diff --git a/test/strcopy.go b/test/strcopy.go new file mode 100644 index 0000000000..6d32baeec5 --- /dev/null +++ b/test/strcopy.go @@ -0,0 +1,29 @@ +// run + +// Copyright 2018 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 that string([]byte(string)) makes a copy and doesn't reduce to +// nothing. (Issue 25834) + +package main + +import ( + "reflect" + "unsafe" +) + +func main() { + var ( + buf = make([]byte, 2<<10) + large = string(buf) + sub = large[10:12] + subcopy = string([]byte(sub)) + subh = *(*reflect.StringHeader)(unsafe.Pointer(&sub)) + subcopyh = *(*reflect.StringHeader)(unsafe.Pointer(&subcopy)) + ) + if subh.Data == subcopyh.Data { + panic("sub and subcopy have the same underlying array") + } +} -- cgit v1.2.1