[CMake] CMAKE_SIZEOF_VOID_P is unset when building libgit2 on Windows

[Sebastian Schuberth]

On 3/24/2016 16:53, Brad King wrote:

>> Configuring libgit2 fails as CMake does not set CMAKE_SIZEOF_VOID_P
>> (nor CMAKE_C_SIZEOF_DATA_PTR), see the attached CMakeCCompiler.cmake file.
>>
>> I tried to search CMake's source code to find out how the value of
>> @CMAKE_C_SIZEOF_DATA_PTR@ is determined in CMakeCCompiler.cmake.in,
>> but I failed. Does anyone have suggestions on how to debug this further,
>> or what the possible root causes might be?
>
> It is supposed to be done here:
>
>   https://cmake.org/gitweb?p=cmake.git;a=blob;f=Modules/CMakeDetermineCompilerABI.cmake;hb=v3.5.0#l23
>   https://cmake.org/gitweb?p=cmake.git;a=blob;f=Modules/CMakeCCompilerABI.c;hb=v3.5.0
>
> The try_compile produces a binary file that encodes strings with the
> information.  Then we use file(STRINGS) to parse the strings right out
> of the binary.  The INFO:sizeof_dptr[...] string contains the size of
> data pointer types.
>
> Check CMakeFiles/CMake{Output,Error}.log to see if anything went wrong
> with that step that was logged.  Otherwise you can add debugging code.

I also just realized CMAKE_C_ABI_COMPILER is set to FALSE in
CMakeCCompiler.cmake. Looking at CMakeError.log was a good hint. I
found:

---8<---
Building C object CMakeFiles/cmTC_c0166.dir/CMakeCCompilerABI.c.obj

C:/Ruby-DevKit/mingw/bin/gcc.exe    -fPIC    -o
CMakeFiles/cmTC_c0166.dir/CMakeCCompilerABI.c.obj   -c "C:/Program
Files (x86)/CMake/share/cmake-3.5/Modules/CMakeCCompilerABI.c"

/usr/bin/sh: -c: line 0: syntax error near unexpected token `('
/usr/bin/sh: -c: line 0: `C:/Ruby-DevKit/mingw/bin/gcc.exe    -fPIC
-o CMakeFiles/cmTC_c0166.dir/CMakeCCompilerABI.c.obj   -c \C:/Program
Files (x86)/CMake/share/cmake-3.5/Modules/CMakeCCompilerABI.c\'
CMakeFiles/cmTC_c0166.dir/build.make:65: recipe for target
'CMakeFiles/cmTC_c0166.dir/CMakeCCompilerABI.c.obj' failed
---8<---

There seems to be some problem in escaping the non-alphanumeric chars
in the path to "CMakeCCompilerABI.c". Any hint how to debug this
further?

Regards,
Sebastian