Make return address extraction build (and even work) on non-MSVC compilers #845
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At a minimum, avoid build breaks on non-MSVC compilers. Turns out that gcc, clang, icc, djgpp, ellcc, and zapcc all define the symbol `__GNUC__` and support the gcc return address extraction extensions. So we need only test two symbols: `_MSC_VER` for MSVC, and `__GNUC__` for everyone else. (clang and icc implement the gcc extensions for compatibility. djgpp is built on top of gcc, so it inherits the gcc extensions. ellcc and zapcc are built on top of clang, so they inherit the gcc extensions via clang.)
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At a minimum, avoid build breaks on non-MSVC compilers.
Turns out that gcc, clang, icc, djgpp, ellcc, and zapcc all define the symbol
__GNUC__and support the gcc return address extraction extensions. So we need only test two symbols:_MSC_VERfor MSVC, and__GNUC__for everyone else.clang and icc implement the gcc extensions for compatibility. djgpp is built on top of gcc, so it inherits the gcc extensions. ellcc and zapcc are built on top of clang, so they inherit the gcc extensions via clang.
For MSVC, you must include
intrin.hbefore using_ReturnAddress(), so we do that explicitly. rather than relying on the kindness of strangers (in this case, relying on apps having theWindowsNumerics.impl.hheader file installed and leaving_XM_NO_INTRINSICS_undefined, so thatdirectxmath.hwill includeintrin.hfor us).I opted against making this a caller-overridable thing, to avoid odr problems. If somebody tries to onboard a new compiler toolchain, the
custom_error_loggertest will fail (null return address), and they can make a PR to this repo to add return address support for it.