[PATCH] CMake: optionaly enable LLVM to be compile with -std=c++11 (default: OFF)

Fri Nov 22 07:40:34 PST 2013

I aggree.

Here is the updated patch. For now, it does just bring the same
functionality as the autotools to cmake.

In a second step, we can change to default to C++11 and add the appropriate
checks to both autotools and cmake. This is were the real fun will happen :)

Cheers,
--
Arnaud

On Fri, Nov 22, 2013 at 1:47 AM, NAKAMURA Takumi <geek4civic at gmail.com>wrote:

> We should reject C++11-incompatible compiler in near future.
>
> 2013/11/22 Arnaud Allard de Grandmaison <arnaud.adegm at gmail.com>:
> > The patch was attempting to mimic autoconf's behaviour...
> >
> > I am not sure to follow you Eric : do you mean this should not be an
> option
> > any more, and must always be set in autoconf and cmake ? It would then
> just
> > be a question of using the c++1 features (or not). In this case, I
> believe a
> > should at least check that the compiler supports '-std=c++11' (or a
> > different wording for non gcc compatible compilers). This would also be
> the
> > right place to check the compiler is a version recent enough as well to
> > build llvm --- in accrodance with c++11 switch huge discussion.
> >
> >
> > On Fri, Nov 22, 2013 at 12:26 AM, Eric Christopher <echristo at gmail.com>
> > wrote:
> >>
> >> On Thu, Nov 21, 2013 at 2:25 PM, Meador Inge <meadori at codesourcery.com>
> >> wrote:
> >> > On 11/21/2013 04:04 PM, Arnaud Allard de Grandmaison wrote:
> >> >
> >> >> In some cases, like when building llvm+lldb with cmake, llvm has to
> be
> >> >> built in
> >> >> c++11 mode. This patch adds the handling of this option. The default
> is
> >> >> OFF for
> >> >> now, but I suspect it will move to ON pretty soon given the
> discussions
> >> >> on the
> >> >> move to c++11 for the llvm codebase.
> >> >
> >> > I am not sure why this is any better than
> -DCMAKE_CXX_FLAGS=-std=c++11,
> >> > but
> >> > maybe someone else can argue that point.  Also, if/when we switch it
> >> > seems like
> >> > the option is no longer useful since disabling means LLVM won't build
> >> > after
> >> > folks start using C++11 features.
> >> >
> >>
> >> *shrug* We can remove the option at that point. I've had one in the
> >> autoconf side for the last few years.
> >>
> >> -eric
> >>
> >> >> diff --git a/CMakeLists.txt b/CMakeLists.txt
> >> >> index f43204f..40cc7b6 100644
> >> >> --- a/CMakeLists.txt
> >> >> +++ b/CMakeLists.txt
> >> >> @@ -179,6 +179,7 @@ else( MSVC )
> >> >>    option(LLVM_ENABLE_WARNINGS "Enable compiler warnings." ON)
> >> >>  endif()
> >> >>
> >> >> +option(LLVM_ENABLE_CXX11 "Compile with C++11 enabled." OFF)
> >> >
> >> > Should this be documented: http://llvm.org/docs/CMake.html ?
> >> >
> >> >>  option(LLVM_ENABLE_PEDANTIC "Compile with pedantic enabled." ON)
> >> >>  option(LLVM_ENABLE_WERROR "Fail and stop if a warning is triggered."
> >> >> OFF)
> >> >>
> >> >> diff --git a/cmake/modules/HandleLLVMOptions.cmake
> >> >> b/cmake/modules/HandleLLVMOptions.cmake
> >> >> index bb41a58..71a5d25 100644
> >> >> --- a/cmake/modules/HandleLLVMOptions.cmake
> >> >> +++ b/cmake/modules/HandleLLVMOptions.cmake
> >> >> @@ -246,6 +246,10 @@ elseif( LLVM_COMPILER_IS_GCC_COMPATIBLE )
> >> >>    if (LLVM_ENABLE_WERROR)
> >> >>      add_llvm_definitions( -Werror )
> >> >>    endif (LLVM_ENABLE_WERROR)
> >> >> +  if (LLVM_ENABLE_CXX11)
> >> >> +    check_cxx_compiler_flag("-Werror -std=c++11" CXX_SUPPORTS_CXX11)
> >> >
> >> > Why do you need to check for "-Werror" too?
> >> >
> >> >> +    append_if(CXX_SUPPORTS_CXX11 "-std=c++11" CMAKE_CXX_FLAGS)
> >> >> +  endif (LLVM_ENABLE_CXX11)
> >> >>  endif( MSVC )
> >> >>
> >> >>  macro(append_common_sanitizer_flags)
> >> >> -- 1.8.3.2
> >> >
> >> >
> >> > --
> >> > Meador Inge
> >> > CodeSourcery / Mentor Embedded
> >> > _______________________________________________
> >> > llvm-commits mailing list
> >> > llvm-commits at cs.uiuc.edu
> >> > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
> >
> >
> >
> > _______________________________________________
> > llvm-commits mailing list
> > llvm-commits at cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
> >
>
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