New CMake sizeof check breaks pthread builds

[RReverser]

I'm seeing an issue when using #18309 (via emscripten 3.1.28) when building libjpeg as part of my project build which uses -pthread and SIMD.

This is the generated jconfigint.h:

/* The size of `size_t', as computed by sizeof. */
#define SIZEOF_SIZE_T  

Here's CMakeCache.txt:

//CHECK_TYPE_SIZE: size_t unknown
SIZE_T:INTERNAL=

Looks like it failed due to -pthread in flags (note the "STANDALONE_WASM does not support shared memories yet"):

Building C object CMakeFiles/cmTC_aee2f.dir/SIZE_T.c.o
/emsdk/upstream/emscripten/emcc   -O3 -pthread -flto -mnontrapping-fptoint -msimd128 -DWASM_SIMD_COMPAT_SLOW -DWASM_BIGINT -DNO_GETENV -DNO_PUTENV  -MD -MT CMakeFiles/cmTC_aee2f.dir/SIZE_T.c.o -MF CMakeFiles/cmTC_aee2f.dir/SIZE_T.c.o.d -o CMakeFiles/cmTC_aee2f.dir/SIZE_T.c.o -c /src/build/deps/jpeg/_build/CMakeFiles/CheckTypeSize/SIZE_T.c
Linking C executable cmTC_aee2f.js
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_aee2f.dir/link.txt --verbose=1
/emsdk/upstream/emscripten/emcc -O3 -pthread -flto -mnontrapping-fptoint -msimd128 -DWASM_SIMD_COMPAT_SLOW -DWASM_BIGINT -DNO_GETENV -DNO_PUTENV  -O3 -pthread -flto -L/src/build/target/lib -sAUTO_JS_LIBRARIES=0 -sAUTO_NATIVE_LIBRARIES=0 -sWASM_BIGINT  @CMakeFiles/cmTC_aee2f.dir/objects1.rsp -o cmTC_aee2f.js @CMakeFiles/cmTC_aee2f.dir/linklibs.rsp
cache:INFO: generating system asset: sysroot/lib/wasm32-emscripten/lto/crt1.o... (this will be cached in "/src/build/deps/emcache/sysroot/lib/wasm32-emscripten/lto/crt1.o" for subsequent builds)
system_libs:INFO: compiled 1 inputs
cache:INFO:  - ok
cache:INFO: generating system library: sysroot/lib/wasm32-emscripten/lto/libstandalonewasm.a... (this will be cached in "/src/build/deps/emcache/sysroot/lib/wasm32-emscripten/lto/libstandalonewasm.a" for subsequent builds)
system_libs:INFO: compiled 20 inputs
cache:INFO:  - ok
cache:INFO: generating system asset: symbol_lists/70de70b14b316e42625f6158cce62c3c32a6f961.txt... (this will be cached in "/src/build/deps/emcache/symbol_lists/70de70b14b316e42625f6158cce62c3c32a6f961.txt" for subsequent builds)
error: library_pthread.js:29: #error "STANDALONE_WASM does not support shared memories yet"
cache:INFO:  - ok
error: library_pthread.js:29: #error "STANDALONE_WASM does not support shared memories yet"
Error: Aborting compilation due to previous errors
emcc: error: '/usr/bin/node /emsdk/upstream/emscripten/src/compiler.js /tmp/tmpdp5fx9nz.json' failed (returned 1)
gmake[1]: *** [CMakeFiles/cmTC_aee2f.dir/build.make:102: cmTC_aee2f.js] Error 1
gmake[1]: *** Deleting file 'cmTC_aee2f.js'
gmake[1]: Leaving directory '/src/build/deps/jpeg/_build/CMakeFiles/CMakeTmp'
gmake: *** [Makefile:127: cmTC_aee2f/fast] Error 2


/src/build/deps/jpeg/_build/CMakeFiles/CheckTypeSize/SIZE_T.c:
#include <sys/types.h>
#include <stdint.h>
#include <stddef.h>


#undef KEY
#if defined(__i386)
# define KEY '_','_','i','3','8','6'
#elif defined(__x86_64)
# define KEY '_','_','x','8','6','_','6','4'
#elif defined(__ppc__)
# define KEY '_','_','p','p','c','_','_'
#elif defined(__ppc64__)
# define KEY '_','_','p','p','c','6','4','_','_'
#elif defined(__aarch64__)
# define KEY '_','_','a','a','r','c','h','6','4','_','_'
#elif defined(__ARM_ARCH_7A__)
# define KEY '_','_','A','R','M','_','A','R','C','H','_','7','A','_','_'
#elif defined(__ARM_ARCH_7S__)
# define KEY '_','_','A','R','M','_','A','R','C','H','_','7','S','_','_'
#endif

#define SIZE (sizeof(size_t))
char info_size[] =  {'I', 'N', 'F', 'O', ':', 's','i','z','e','[',
  ('0' + ((SIZE / 10000)%10)),
  ('0' + ((SIZE / 1000)%10)),
  ('0' + ((SIZE / 100)%10)),
  ('0' + ((SIZE / 10)%10)),
  ('0' +  (SIZE    % 10)),
  ']',
#ifdef KEY
  ' ','k','e','y','[', KEY, ']',
#endif
  '\0'};

#ifdef __CLASSIC_C__
int main(argc, argv) int argc; char *argv[];
#else
int main(int argc, char *argv[])
#endif
{
  int require = 0;
  require += info_size[argc];
  (void)argv;
  return require;
}


Determining size of unsigned long failed with the following output:
Change Dir: /src/build/deps/jpeg/_build/CMakeFiles/CMakeTmp

@sbc100

[RReverser]

It's probably possible to move flags around so that they don't apply to configure stage, but I suspect this might break more projects than #18309 fixed and might be better to revert until we have a better solution.

[sbc100]

I think maybe we should make STANDALONE_WASM works with shared memory. Either that or inject -sUSE_PTHREADS=0 when building this test, but that seems less correct.

[RReverser]

I think maybe we should make STANDALONE_WASM works with shared memory.

Sure, that would be ideal, but I'm not sure how much effort it is, so a revert for now to unbreak builds seemed like a safer suggestion.

[sbc100]

Oh sorry, I didn't see the suggestions of a revert. I'm fine with reverting for now.