Set CC to clang when GYP_DEFINES=clang=1.

Set CC to clang when GYP_DEFINES=clang=1.

This makes it a lot easier to build with clang, since setting the GYP_DEFINES
is now the only thing one has to do. The rest is set automatically.
In preparation of setting clang=1 in build/common.gypi on mac.

Depends on http://codereview.chromium.org/7779041/ . Idea and xcode
part of the patch by Mark.

BUG=none
TEST= Set GYP_DEFINES=clang=1, create xcode and make projects
1.) Building with Xcode 3.2 uses clang
2.) Building with Xcode 4 gives functional fixits
3.) Building with make uses clang both for host and target
4.) Building with xcodebuild and goma still works on mac
5.) Building with make and goma still works

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=99835

[Evan Martin, 2011-09-06 17:41:16]

http://codereview.chromium.org/7779039/diff/1/build/common.gypi
File build/common.gypi (right):

http://codereview.chromium.org/7779039/diff/1/build/common.gypi#newcode1680
build/common.gypi:1680: 'LDPLUSPLUS': '$(SOURCE_ROOT)/<(clang_dir)/clang++',
Where does SOURCE_ROOT come from?

[Nico, 2011-09-06 17:47:08]

http://codereview.chromium.org/7779039/diff/1/build/common.gypi
File build/common.gypi (right):

http://codereview.chromium.org/7779039/diff/1/build/common.gypi#newcode1680
build/common.gypi:1680: 'LDPLUSPLUS': '$(SOURCE_ROOT)/<(clang_dir)/clang++',
On 2011/09/06 17:41:16, Evan Martin wrote:
> Where does SOURCE_ROOT come from?

I think it's one of the many magic environment variables that xcode sets when
building, see
http://developer.apple.com/library/mac/#documentation/DeveloperTools/Referenc...

[Evan Martin, 2011-09-06 17:56:44]

LGTM

[Mark Mentovai, 2011-09-07 01:36:24]

LGTM.

Looks familiar. :)

http://codereview.chromium.org/7779039/diff/1/build/common.gypi
File build/common.gypi (right):

http://codereview.chromium.org/7779039/diff/1/build/common.gypi#newcode2027
build/common.gypi:2027: ['LINK',
'third_party/llvm-build/Release+Asserts/bin/clang++'],
This is fine for now.

We’ll need to split this up in the same way that Xcode does in order to migrate
the official build to make, so that make doesn’t link C-only programs as C++.

[Nico, 2011-09-07 02:59:22]

On Tue, Sep 6, 2011 at 6:36 PM,  <mark@chromium.org> wrote:
> LGTM.
>
> Looks familiar. :)

:-) I added attribution before committing.

>
>
> http://codereview.chromium.org/7779039/diff/1/build/common.gypi
> File build/common.gypi (right):
>
> http://codereview.chromium.org/7779039/diff/1/build/common.gypi#newcode2027
> build/common.gypi:2027: ['LINK',
> 'third_party/llvm-build/Release+Asserts/bin/clang++'],
> This is fine for now.
>
> We’ll need to split this up in the same way that Xcode does in order to
> migrate the official build to make, so that make doesn’t link C-only
> programs as C++.
>
> http://codereview.chromium.org/7779039/
>