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ianlancetaylorianlancetaylor
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cmd/go: always use --whole-archive for gccgo packages
This is, in effect, what the gc toolchain does. It fixes cases where Go code refers to a C global variable; without this, if the global variable was the only thing visible in the C code, the generated cgo file might not get pulled in from the archive, leaving the Go variable uninitialized. This was reported against gccgo as https://gcc.gnu.org/PR68255 . Change-Id: I3e769dd174f64050ebbff268fbbf5e6fab1e2a1b Reviewed-on: https://go-review.googlesource.com/16775 Run-TryBot: Ian Lance Taylor <[email protected]> Reviewed-by: Russ Cox <[email protected]>
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6 files changed

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‎misc/cgo/test/cgo_test.go‎

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@@ -66,5 +66,6 @@ func Test9557(t *testing.T) { test9557(t) }
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func Test10303(t *testing.T) { test10303(t, 10) }
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func Test11925(t *testing.T) { test11925(t) }
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func Test12030(t *testing.T) { test12030(t) }
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func TestGCC68255(t *testing.T) { testGCC68255(t) }
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func BenchmarkCgoCall(b *testing.B) { benchCgoCall(b) }

‎misc/cgo/test/gcc68255.go‎

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// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package cgotest
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import (
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"testing"
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"./gcc68255"
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)
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func testGCC68255(t *testing.T) {
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if !gcc68255.F() {
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t.Error("C global variable was not initialized")
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}
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}

‎misc/cgo/test/gcc68255/a.go‎

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// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Test that it's OK to have C code that does nothing other than
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// initialize a global variable. This used to fail with gccgo.
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package gcc68255
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/*
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#include "c.h"
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*/
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import "C"
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func F() bool {
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return C.v != nil
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}

‎misc/cgo/test/gcc68255/c.c‎

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// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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static void f(void) {
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}
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void (*v)(void) = f;

‎misc/cgo/test/gcc68255/c.h‎

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// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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extern void (*v)(void);

‎src/cmd/go/build.go‎

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@@ -2599,17 +2599,9 @@ func (tools gccgoToolchain) ld(b *builder, root *action, out string, allactions
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}
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}
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switch ldBuildmode {
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case "c-archive", "c-shared":
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ldflags = append(ldflags, "-Wl,--whole-archive")
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}
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ldflags = append(ldflags, "-Wl,--whole-archive")
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ldflags = append(ldflags, afiles...)
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switch ldBuildmode {
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case "c-archive", "c-shared":
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ldflags = append(ldflags, "-Wl,--no-whole-archive")
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}
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ldflags = append(ldflags, "-Wl,--no-whole-archive")
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ldflags = append(ldflags, cgoldflags...)
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ldflags = append(ldflags, envList("CGO_LDFLAGS", "")...)

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