compilers: cpp: wire up stdlib assertions #12683
Merged
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None of the options set here affect ABI and are intended for detecting constraint violations.
For GCC, we simply need to set -D_GLIBCXX_ASSERTIONS.
For Clang, the situation is far more complicated:
LLVM 18 uses a 'hardened mode' (https://libcxx.llvm.org/Hardening.html). There are several levels of severity available here. I've chosen _LIBCPP_HARDENING_MODE_DEBUG for now given it does the most but does not affect ABI, but we could change it to something more lightweight.
LLVM 17 uses a similar approach to libstdc++ called '_LIBCPP_ENABLE_ASSERTIONS'
Note that LLVM 17 while in development had fully deprecated _LIBCPP_ENABLE_ASSERTIONS in favour of hardened, but changed its mind last-minute: https://discourse.llvm.org/t/rfc-hardening-in-libc/73925/4.