C99 compile - static_assert failure

[cscd98]

With C standard of C99 static_assert is no longer available causing a compile failure:

hidapi/windows/hidapi_descriptor_reconstruct.h

Line 133 in a758717

static_assert(sizeof(struct hid_pp_link_collection_node_) == 16,

[mcuee]

What is the compiler used to trigger this issue?

Take note we only support MSYS2 GCC/clang and MSVC under Windows.

[cscd98]

Hi, it would had been the latest msys2 release on Windows.

[mcuee]

I just tried latest MSYS2 mingw64 toolchain under Windows 11 and there is no issue to build latest hidapi git.

MINGW64 /c/work/libusb/hidapi
$ gcc -v
Using built-in specs.
COLLECT_GCC=C:\msys64\mingw64\bin\gcc.exe
COLLECT_LTO_WRAPPER=C:/msys64/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/15.2.0/lto-wrapper.exe
Target: x86_64-w64-mingw32
Configured with: ../gcc-15.2.0/configure --prefix=/mingw64 --with-local-prefix=/mingw64/local --with-native-system-header-dir=/mingw64/include --libexecdir=/mingw64/lib --enable-bootstrap --enable-checking=release --with-arch=nocona --with-tune=generic --enable-mingw-wildcard --enable-languages=c,lto,c++,fortran,ada,objc,obj-c++,jit --enable-shared --enable-static --enable-libatomic --enable-threads=posix --enable-graphite --enable-fully-dynamic-string --enable-libstdcxx-backtrace=yes --enable-libstdcxx-filesystem-ts --enable-libstdcxx-time --disable-libstdcxx-pch --enable-lto --enable-libgomp --disable-libssp --disable-multilib --disable-rpath --disable-win32-registry --disable-nls --disable-werror --disable-symvers --with-libiconv --with-system-zlib --with-gmp=/mingw64 --with-mpfr=/mingw64 --with-mpc=/mingw64 --with-isl=/mingw64 --with-pkgversion='Rev8, Built by MSYS2 project' --with-bugurl=https://github.com/msys2/MINGW-packages/issues --with-gnu-as --with-gnu-ld --with-libstdcxx-zoneinfo=yes --disable-libstdcxx-debug --enable-plugin --with-boot-ldflags=-static-libstdc++ --with-stage1-ldflags=-static-libstdc++
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 15.2.0 (Rev8, Built by MSYS2 project)

$ cat build_cmake_mingw64_1.sh
cmake -B buildmingw64 -S . -DCMAKE_BUILD_TYPE=RelWithDebInfo -DHIDAPI_WITH_TESTS=ON -DHIDAPI_BUILD_PP_DATA_DUMP=ON -DCMAKE_INSTALL_PREFIX=buildmingw64 -DHIDAPI_BUILD_HIDTEST=ON
cmake --build buildmingw64 --target install

$ sh build_cmake_mingw64_1.sh
-- Building for: Ninja
-- The C compiler identification is GNU 15.2.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: C:/msys64/mingw64/bin/cc.exe - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- hidapi: v0.16.0
-- Building hidtest
-- Configuring done (0.8s)
-- Generating done (0.0s)
-- Build files have been written to: C:/work/libusb/hidapi/buildmingw64
[10/11] Install the project...-- Install configuration: "RelWithDebInfo"
-- Installing: C:/work/libusb/hidapi/buildmingw64/lib/libhidapi.dll.a
-- Installing: C:/work/libusb/hidapi/buildmingw64/bin/libhidapi.dll
-- Installing: C:/work/libusb/hidapi/buildmingw64/include/hidapi/hidapi.h
-- Installing: C:/work/libusb/hidapi/buildmingw64/include/hidapi/hidapi_winapi.h
-- Installing: C:/work/libusb/hidapi/buildmingw64/lib/pkgconfig/hidapi.pc
-- Installing: C:/work/libusb/hidapi/buildmingw64/bin/pp_data_dump.exe
-- Installing: C:/work/libusb/hidapi/buildmingw64/lib/cmake/hidapi/libhidapi.cmake
-- Installing: C:/work/libusb/hidapi/buildmingw64/lib/cmake/hidapi/libhidapi-relwithdebinfo.cmake
-- Installing: C:/work/libusb/hidapi/buildmingw64/lib/cmake/hidapi/hidapi-config-version.cmake
-- Installing: C:/work/libusb/hidapi/buildmingw64/lib/cmake/hidapi/hidapi-config.cmake
-- Installing: C:/work/libusb/hidapi/buildmingw64/bin/hidtest.exe

[cscd98]

It only occurs when setting the c standard to 99.

set(CMAKE_C_STANDARD 99)

[Youw]

If this is the only breaking code for C11, I guess we could have a condition on C standard for the compilation.
But I'd like to know what forces you to use C99 to compile HIDAPI?