code review 12350044: build: on OS X use clang instead of gcc (issue 12350044)

[r...@golang.org]

Reviewers: golang-dev1,

Message:
Hello golan...@googlegroups.com,

I'd like you to review this change to
https://code.google.com/p/go/


Description:
build: on OS X use clang instead of gcc

Fixes issue 5822.
Will no doubt cause other problems, but Apple has forced our hand.

Please review this at https://codereview.appspot.com/12350044/

Affected files:
M src/cmd/dist/build.c
M src/cmd/go/build.go


Index: src/cmd/dist/build.c
===================================================================
--- a/src/cmd/dist/build.c
+++ b/src/cmd/dist/build.c
@@ -617,8 +617,17 @@
// set up gcc command line on first run.
if(gccargs.len == 0) {
xgetenv(&b, "CC");
- if(b.len == 0)
- bprintf(&b, "gcc");
+ if(b.len == 0) {
+ // Use clang on OS X, because gcc is deprecated there.
+ // Xcode for OS X 10.9 Mavericks will ship a fake "gcc" binary that
+ // actually runs clang. We prepare different command
+ // lines for the two binaries, so it matters what we call it.
+ // See golang.org/issue/5822.
+ if(streq(gohostos, "darwin")
+ bprintf(&b, "clang");
+ else
+ bprintf(&b, "gcc");
+ }
clang = contains(bstr(&b), "clang");
splitfields(&gccargs, bstr(&b));
for(i=0; i<nelem(proto_gccargs); i++)
Index: src/cmd/go/build.go
===================================================================
--- a/src/cmd/go/build.go
+++ b/src/cmd/go/build.go
@@ -1771,6 +1771,19 @@
return b.run(p.Dir, p.ImportPath, nil, cmd, "-o", out, obj, flags)
}

+var defaultCC = "gcc"
+
+func init() {
+ // Use clang on OS X, because gcc is deprecated there.
+ // Xcode for OS X 10.9 Mavericks will ship a fake "gcc" binary that
+ // actually runs clang. We prepare different command
+ // lines for the two binaries, so it matters what we call it.
+ // See golang.org/issue/5822.
+ if runtime.GOOS == "darwin" {
+ defaultCC = "clang"
+ }
+}
+
// gccCmd returns a gcc command line prefix
func (b *builder) gccCmd(objdir string) []string {
return b.ccompilerCmd("CC", "gcc", objdir)

[Brad Fitzpatrick]

LGTM

On all versions? Even 10.6? Did clang work then, having all the flags we need?

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[Russ Cox]

I have no idea what the version story is. We may need to be more precise about that. For now I want to see what breaks.

[Brad Fitzpatrick]

Go for it.  I have a 10.6 machine at home still which I can test later.

[r...@golang.org]

Hello golan...@googlegroups.com, brad...@golang.org (cc:
golan...@googlegroups.com),

Please take another look.


https://codereview.appspot.com/12350044/

[Russ Cox]

PTAL 

Added logic to cmd/cgo and disabled the cgo -godefs test.

[Keith Randall]

I get errors when running this on 10.6:

# crypto/x509

/var/folders/a0/a0ATNr3xHliked0p+c3lIU+++TI/-Tmp-/go-build255322058/crypto/x509/_obj/_cgo_gotypes.go:14: syntax error: unexpected type, expecting name

/var/folders/a0/a0ATNr3xHliked0p+c3lIU+++TI/-Tmp-/go-build255322058/crypto/x509/_obj/_cgo_gotypes.go:26: syntax error: unexpected .

:7[/var/folders/a0/a0ATNr3xHliked0p+c3lIU+++TI/-Tmp-/go-build255322058/crypto/x509/_obj/_cgo_gotypes.go:34]: syntax error: unexpected type, expecting name

:8[/var/folders/a0/a0ATNr3xHliked0p+c3lIU+++TI/-Tmp-/go-build255322058/crypto/x509/_obj/_cgo_gotypes.go:35]: syntax error: unexpected type, expecting name

On Fri, Aug 2, 2013 at 10:46 AM, Russ Cox <r...@golang.org> wrote:

PTAL 

Added logic to cmd/cgo and disabled the cgo -godefs test.

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[Russ Cox]

PTAL

Clang is now only used as the default on OS X 10.8 and later.

[brad...@golang.org]

LGTM


https://codereview.appspot.com/12350044/

[r...@golang.org]

*** Submitted as
https://code.google.com/p/go/source/detail?r=ede1d772501b ***

build: on OS X 10.8 and later, use clang instead of gcc

Fixes issue 5822.
Will no doubt cause other problems, but Apple has forced our hand.

R=golang-dev, bradfitz, khr
CC=golang-dev
https://codereview.appspot.com/12350044


https://codereview.appspot.com/12350044/

[Brad Fitzpatrick]

Breaks on Linux:

# Building C bootstrap tool.

cmd/dist

cmd/dist/build.c: In function 'install':

cmd/dist/build.c:642:5: error: 'clang' may be used uninitialized in this function [-Werror=uninitialized]

cc1: all warnings being treated as errors

Build complete, duration 1.367061013s. Result: error: exit status 1

[Russ Cox]

Fixing, thanks.

[Francisco Souza]

Breaks on 10.8 too:

% clang --version
Apple LLVM version 4.2 (clang-425.0.24) (based on LLVM 3.2svn)
Target: x86_64-apple-darwin12.4.0
Thread model: posix
% ./make.bash

# Building C bootstrap tool.
cmd/dist

cmd/dist/build.c:642:6: error: variable 'clang' is uninitialized when
used here [-Werror,-Wuninitialized]
if(clang) {
^~~~~
cmd/dist/build.c:592:39: note: initialize the variable 'clang' to
silence this warning
bool islib, ispkg, isgo, stale, clang;
^
= 0
1 error generated.

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--
Francisco Souza