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f0937b83d9
Summary: Issue reported by @ryandesign and @MarcusCalhoun-Lopez. CMake doesn't support spaces in flags. This caused older versions of gcc to ignore the unknown flag "-z noexecstack" on MacOS since it was interpreted as a single flag, not two separate flags. Then, during compilation it was treated as "-z" "noexecstack", which was correctly forwarded to the linker. But the MacOS linker does not support `-z noexecstack` so compilation failed. The fix is to use `-Wl,-z,noexecstack`. This is never misinterpreted by a compiler. However, not all compilers support this syntax to forward flags to the linker. To fix this issue, we check if all the relevant `noexecstack` flags have been successfully set, and if they haven't we disable assembly. See also PR#4056 and PR#4061. I decided to go a different route because this is simpler. It might not successfully set these flags on some compilers, but in that case it also disables assembly, so they aren't required. Test Plan: ``` mkdir build-cmake cmake ../build/cmake/CMakeLists.txt make -j ``` See that the linker flag is successfully detected & that assembly is enabled. Run the same commands on MacOS which doesn't support `-Wl,-z,noexecstack` and see that everything compiles and that `LD_FLAG_WL_Z_NOEXECSTACK` and `ZSTD_HAS_NOEXECSTACK` are both false.