https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117683
--- Comment #7 from R. Diez <rdiez-2006 at rd10 dot de> --- About using C++ exceptions without RTTI, I tried to build a toolchain for ARM (arm-none-eabi) with -fno-rtti, and I got the following compilation errors (they may be more): File eh_arm.cc: [...]/gcc-14.2.0/libstdc++-v3/libsupc++/eh_arm.cc: In function '__cxxabiv1::__cxa_type_match_result __cxa_type_match(_Unwind_Control_Block*, const std::type_info*, bool, void**)': [...]/gcc-14.2.0/libstdc++-v3/libsupc++/eh_arm.cc:57:46: error: cannot use 'typeid' with '-fno-rtti' 57 | throw_type = &typeid(abi::__forced_unwind); [...]/gcc-14.2.0/libstdc++-v3/libsupc++/eh_arm.cc:59:50: error: cannot use 'typeid' with '-fno-rtti' 59 | throw_type = &typeid(abi::__foreign_exception); File eh_call.cc: [...]/gcc-14.2.0/libstdc++-v3/libsupc++/eh_call.cc:130:64: error: cannot use 'typeid' with '-fno-rtti' 130 | const std::type_info& bad_exc = typeid(std::bad_exception); So I gather that I need to enable RTTI when building the toolchain. Questions are: 1) Is that the case only for ARM, but not for other architectures? 2) Is that only a requirement for libsupc++? Or are there other GCC components which may need RTTI, like perhaps libstdc++? Can I then specify something like "-frtti" to enable RTTI just for libsupc++, and -fno-rtti for the rest? How do I do that with GCC's ./configure script or make invocation? I am doing it with "make CXXFLAGS_FOR_TARGET=-fno-rtti" at the moment. 3) If GCC is built with RTTI, is it really safe to disable RTTI in my firmware? I would then be mixing RTTI code from libsupc++, and maybe from other GCC components, with non-RTTI code from my application.
