r193934 - Default to use libc++ on OS X 10.9+ and iOS 7+.

[Nico Weber]

On Tue, Nov 5, 2013 at 9:44 AM, Bob Wilson <bob.wilson at apple.com> wrote:

> On OS X the libc++ headers are meant to be installed along with clang.  If
> you check out the libc++ sources in the LLVM projects directory, they
> should be installed in the right place.
>

Thanks, that makes sense. Should
http://clang.llvm.org/get_started.htmlmention checking out libc++,
since it sounds that's now a requirement on OS
X?


>
> On Nov 5, 2013, at 9:42 AM, Howard Hinnant <hhinnant at apple.com> wrote:
>
> > When I use tot clang, (and want libc++), I will forbid clang from
> looking the std::headers, and then tell it exactly where the headers are,
> e.g.:
> >
> > $ clang++ -stdlib=libc++ -std=c++11 -nostdinc++ -I../libcxx/include
> test.cpp
> >
> > Howard
> >
> > On Nov 5, 2013, at 12:35 PM, Nico Weber <thakis at chromium.org> wrote:
> >
> >> In addition to the performance issues, libc++ apparently can't be found
> by clang: http://llvm.org/bugs/show_bug.cgi?id=17821
> >>
> >>
> >> On Sat, Nov 2, 2013 at 10:35 PM, Bob Wilson <bob.wilson at apple.com>
> wrote:
> >> I’m not familiar with those performance issues, so I’m CC’ing Howard in
> case he can provide any details on those issues.  In general, we’re in the
> process of migrating away from libstdc++ on OS X and iOS, so we really do
> want the default to be libc++ regardless of the language mode.  If you have
> particularly performance sensitive code, you can always choose to use
> libstdc++.
> >>
> >> On Nov 2, 2013, at 7:05 PM, Nico Weber <thakis at chromium.org> wrote:
> >>
> >>> Thanks for upstreaming this!
> >>>
> >>> Should this only happen in C++11 mode? libc++ seems to be measurably
> slower than libstdc++ in C++03 mode (PR17703, PR14554, PR14555).
> >>>
> >>>
> >>> On Sat, Nov 2, 2013 at 4:19 PM, Bob Wilson <bob.wilson at apple.com>
> wrote:
> >>> Author: bwilson
> >>> Date: Sat Nov  2 18:19:53 2013
> >>> New Revision: 193934
> >>>
> >>> URL: http://llvm.org/viewvc/llvm-project?rev=193934&view=rev
> >>> Log:
> >>> Default to use libc++ on OS X 10.9+ and iOS 7+.
> >>>
> >>> Modified:
> >>>    cfe/trunk/lib/Driver/ToolChains.cpp
> >>>    cfe/trunk/test/PCH/cxx-typeid.cpp
> >>>
> >>> Modified: cfe/trunk/lib/Driver/ToolChains.cpp
> >>> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/ToolChains.cpp?rev=193934&r1=193933&r2=193934&view=diff
> >>>
> ==============================================================================
> >>> --- cfe/trunk/lib/Driver/ToolChains.cpp (original)
> >>> +++ cfe/trunk/lib/Driver/ToolChains.cpp Sat Nov  2 18:19:53 2013
> >>> @@ -839,6 +839,12 @@ DerivedArgList *Darwin::TranslateArgs(co
> >>>     }
> >>>   }
> >>>
> >>> +  // Default to use libc++ on OS X 10.9+ and iOS 7+.
> >>> +  if (((isTargetMacOS() && !isMacosxVersionLT(10, 9)) ||
> >>> +       (isTargetIPhoneOS() && !isIPhoneOSVersionLT(7, 0))) &&
> >>> +      !Args.getLastArg(options::OPT_stdlib_EQ))
> >>> +    DAL->AddJoinedArg(0, Opts.getOption(options::OPT_stdlib_EQ),
> "libc++");
> >>> +
> >>>   // Validate the C++ standard library choice.
> >>>   CXXStdlibType Type = GetCXXStdlibType(*DAL);
> >>>   if (Type == ToolChain::CST_Libcxx) {
> >>>
> >>> Modified: cfe/trunk/test/PCH/cxx-typeid.cpp
> >>> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/PCH/cxx-typeid.cpp?rev=193934&r1=193933&r2=193934&view=diff
> >>>
> ==============================================================================
> >>> --- cfe/trunk/test/PCH/cxx-typeid.cpp (original)
> >>> +++ cfe/trunk/test/PCH/cxx-typeid.cpp Sat Nov  2 18:19:53 2013
> >>> @@ -1,8 +1,8 @@
> >>> // Test this without pch.
> >>> -// RUN: %clang_cc1 -include %S/cxx-typeid.h -fsyntax-only -verify %s
> >>> +// RUN: %clang_cc1 -include %S/cxx-typeid.h -fsyntax-only
> -stdlib=libstdc++ -verify %s
> >>>
> >>> -// RUN: %clang_cc1 -x c++-header -emit-pch -o %t.pch %S/cxx-typeid.h
> >>> -// RUN: %clang_cc1 -include-pch %t.pch -fsyntax-only -verify %s
> >>> +// RUN: %clang_cc1 -x c++-header -emit-pch -stdlib=libstdc++ -o
> %t.pch %S/cxx-typeid.h
> >>> +// RUN: %clang_cc1 -include-pch %t.pch -fsyntax-only
> -stdlib=libstdc++ -verify %s
> >>>
> >>> // expected-no-diagnostics
> >>>
> >>>
> >>>
> >>> _______________________________________________
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> >>> cfe-commits at cs.uiuc.edu
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> >>>
> >>
> >>
> >
>
>
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