[MinGW][libclang] Allow simultaneous shared and static lib

[mati865]

Summary

It builds fine for MinGW on Windows.

[mstorsjo]

Does the static lib built in this case include any dllexport attributes (that can cause issues if linking it statically into another DLL)?

[mati865]

We had this patch at MSYS2 for years and I'm not aware of any issues with the static library.
I think the library looks fine:

$ nm lib/liblibclang.a | grep __imp_
                 U __imp___acrt_iob_func
                 U __imp___acrt_iob_func
                 U __imp_GetModuleFileNameA
                 U __imp_VirtualQuery
                 U __imp___acrt_iob_func
                 U __imp___acrt_iob_func
                 U __imp___acrt_iob_func

[mstorsjo]

In D87539#2269385, @mati865 wrote:

We had this patch at MSYS2 for years and I'm not aware of any issues with the static library.
I think the library looks fine:

$ nm lib/liblibclang.a | grep __imp_
                 U __imp___acrt_iob_func
                 U __imp___acrt_iob_func
                 U __imp_GetModuleFileNameA
                 U __imp_VirtualQuery
                 U __imp___acrt_iob_func
                 U __imp___acrt_iob_func
                 U __imp___acrt_iob_func

What about llvm-readobj --coff-directives | grep -i export:? The effect is often very subtle - if you build another DLL, that has no explicit dllexports of its own but rely on the default of exporting all symbols - it fails if a statically linked dependency contains explicit dllexports and only exports the dependency's symbols.

[mati865]

bin/llvm-readobj --coff-directives lib/liblibclang.dll.a | grep -i export shows nothing.

[mstorsjo]

In D87539#2269442, @mati865 wrote:

bin/llvm-readobj --coff-directives lib/liblibclang.dll.a | grep -i export shows nothing.

That's the import library, not the static library.

[mati865]

Sorry, pasted wrong command. I was curious if import library has it (since static one did not) but in the end neither import nor static library shows any export.

[mstorsjo]

LGTM then! Can apply it a bit later.

[mati865]

Thanks.

clang/tools/libclang/CMakeLists.txt

 if(LLVM_ENABLE_PIC OR (WIN32 AND NOT LIBCLANG_BUILD_STATIC))
   set(ENABLE_SHARED SHARED)
 endif()
 
 if(NOT LLVM_ENABLE_PIC OR LIBCLANG_BUILD_STATIC)
   set(ENABLE_STATIC STATIC)
 endif()
 
-if (WIN32 AND ENABLE_SHARED AND ENABLE_STATIC)
+if (MSVC AND ENABLE_SHARED AND ENABLE_STATIC)
   unset(ENABLE_STATIC)
 endif()
 
 if(MSVC)
   set(output_name "libclang")
 else()
   set(output_name "clang")
 endif()