Jonathan Wakely
a8e02a00a0
This allows std::make_exception_ptr to be used in a translation unit compiled with -fno-exceptions. This works because the new implementation added for PR 68297 doesn't need to throw or catch anything. The catch is there to handle exceptions from the constructor of the exception object, which we can assume won't happen in a -fno-exceptions TU and so use the __catch macro instead. If the constructor does throw (because it's defined in a different TU which was compiled with exceptions enabled) then that exception will propagate to the make_exception_ptr caller. That seems acceptable for a program that is trying to mix & match TUs compiled with and without exceptions, and using types that throw when constructed. That should be rare, and can't reasonably be expected to have sensible behaviour. This also enables the new implementation for targets that use a non-standard calling convention for the exceptionDestructor callback (specifically, mingw, which uses __thiscall). All we need to do is mark the __dest_thunk function template with the right calling convention. Finally, the useless no-op definition of make_exception_ptr (which is only used if both RTTI and exceptions are disabled) is marked always_inline, to ensure that the linker won't keep that definition and discard the functional ones when both definitions of the function are present in the link. An alternative would be to add the abi_tag attribute to the useless definition, but making it always_inline should work, and it's small enough to always be inlined reliably. libstdc++-v3/ChangeLog: PR libstdc++/85813 * libsupc++/exception_ptr.h (__dest_thunk): Add macro for destructor calling convention. (make_exception_ptr): Enable non-throwing implementation for -fno-exceptions and for non-standard calling conventions. Use always_inline attribute on the useless no-rtti no-exceptions definition. * testsuite/18_support/exception_ptr/64241.cc: Add -fno-rtti so the no-op implementation is still used.
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