[cfe-dev] How to build shared and static libclang* files

[Wink Saville via cfe-dev]

I've updated my POC,
https://github.com/winksaville/llvm-project/tree/Support-building-shared-and-static-libraries-simultaneously,
so it now provides cmake options for building static and shared
libclang* libraries. By default its doing both. This is modeled after
how libunwind works.

On Tue, May 7, 2019 at 5:56 PM Wink Saville <wink at saville.com> wrote:
>
> So I've got a proof of concept for building both SHARED and STATIC libraries.
> The simple implementation that creates libclangARCMigrate.a and
> libclangARCMigrate.so
> is on my llvm-project fork:
> https://github.com/winksaville/llvm-project/commit/fb314421c1dd404648e7046c6ef074e93d28e4c1
>
> As it turns out llvm_add_library already supported building both, but
> I had to have it build the shared library first rather than the static library.
> Without this change clang can be built but it fails when run:
>
>   $ ./bin/clang-9 --version
>   : CommandLine Error: Option 'use-dbg-addr' registered more than once!
>   LLVM ERROR: inconsistency in registered CommandLine options
>
> The reason it fails is because it was linked with libclangARCMigrate.so.9svn
> rahter than the correct library, libclangARCMigrate.a.
>
>
> As you can see in the link above the code changes were fairly small:
>
>   clang/cmake/modules/AddClang.cmake add_clang_library:
>
>    - Add support for STATIC, SHARED or both
>    - Add support for OUTPUT_NAME
>
>   llvm/cmake/modules/AddLLVM.cmake llvm_add_library:
>
>    - Changed so when both SHARED and STATIC are passed SHARED is built
>      first. Without this change llvm_add_library causes the shared libraries
>      to be linked to clang rather than the static library. This compiles
>      successfully but clang fails when run with:
>
>   clang/lib/ARCMigrate/CMakeLists.txt:
>
>    - Added STATIC SHARED so both libclangARCMigrate.a and
>      libclangARCMigrate.so are built
>
>
> The result of building with the change is both static and shared libraries
> of libclangARCMigrate are created:
>
>   $ ls -al lib/*ARCM*
>   -rw-r--r-- 1 wink users  8541496 May  7 17:37 lib/libclangARCMigrate.a
>   lrwxrwxrwx 1 wink users       26 May  7 17:37
> lib/libclangARCMigrate.so -> libclangARCMigrate.so.9svn
>   -rwxr-xr-x 1 wink users 37597048 May  7 17:37 lib/libclangARCMigrate.so.9svn
>
> And clang runs:
>
>   $ ./bin/clang --version
>   clang version 9.0.0 (git at github.com:winksaville/llvm-project
> fb314421c1dd404648e7046c6ef074e93d28e4c1)
>   Target: x86_64-unknown-linux-gnu
>   Thread model: posix
>   InstalledDir:
> /home/wink/prgs/llvm/llvm-project/build-Support-building-shared-and-static-libraries-simultaneously/./bin
>
>
> Feed back welcome!
>
> -- Wink