[cfe-dev] [libcxx] build system questions

[Howard Hinnant]

On Dec 8, 2010, at 12:00 AM, Michael Spencer wrote:

> On Tue, Dec 7, 2010 at 7:55 PM, Howard Hinnant <hhinnant at apple.com> wrote:
>> On Dec 7, 2010, at 7:49 PM, Michael Spencer wrote:
>> 
>>> On Mon, Dec 6, 2010 at 9:06 AM, Howard Hinnant <hhinnant at apple.com> wrote:
>>>> I think we should start out with a simple question:  What problem are we attempting to solve?
>>>> 
>>>> -Howard
>>> 
>>> If we want Windows support (which I do :P), CMake is the way to go.
>>> I'm willing to do it, targeting POSIX-like platforms for now, as doing
>>> a Windows port is a much larger project. It's also possible to do it
>>> without requiring explicit source lists, even though there aren't that
>>> many to begin with.
>> 
>> Windows support seems motivating to me.  The build system will probably be the easy part.  locale support will be more challenging.  Another challenging part may be the low-level stuff such as type_info and exception_ptr.
>> 
>> -Howard
> 
> locale will be a lot of work, but not too hard. type_info should be
> easy for clang, but hard for MSVC (if we even plan to support MSVC).
> I'm afraid to look at exception_ptr :P. LLVM/Clang can't even do
> exceptions on Windows currently.
> 
> I've attached a very rough patch for Linux CMake support. It has a few
> hard coded paths for my system which will need to be configured by
> CMake instead. It compiles with both g++ and clang++, however, the lit
> tests only work with g++ because clang++ doesn't understand
> -nodefaultlibs.
> 
> I just finished running all the tests. 2506 out of 4217 passed (~60%).
> Most failures are due to undefined references, and the rest are due to
> -fno_exceptions or -fno-rtti which I had to set because
> __gxx_personality_v0 is part of libstdc++ (I also set
> _LIBCXX_NO_{EXCEPTIONS,RTTI}, but it doesn't always seem to be
> honored).
> 
> TODO:
> * Fix RPATH for shared libraries. I gave up and made it static.
> * Add support for host and target triples, and auto-select host.
> * Support Darwin
> * Add CMake options for all the features.
> * Configure the lit test config for the build or install dir
> * Make clang honor -nodefaultlibs
> * Figure out what libs are needed on Linux.
> * Add "make check"
> 
> - Michael Spencer
> <really-hacky-cmake.patch>

I've reviewed this patch.  Thanks for working on this.  I think it is premature to check it in at this point (with bigcheese and all :-)).  However I can see something like this coexisting with the current build system.  And I think getting libc++ to work with clang/Windows is a very good goal.

I'm also going to be working on modifying libc++ to run on top of gcc's libsupc++.  Perhaps this will help the clang/Windows port?

-Howard