On Thu, 20 Feb 2025 at 17:06, Thomas Schwinge <tschwi...@baylibre.com> wrote: > > In a '-fno-exceptions' configuration: > > In file included from > ../../../../../source-gcc/libstdc++-v3/src/c++20/format.cc:29: > [...]/build-gcc/[...]/libstdc++-v3/include/format: In function ‘void > std::__throw_format_error(const char*)’: > [...]/build-gcc/[...]/libstdc++-v3/include/format:200:36: error: unused > parameter ‘__what’ [-Werror=unused-parameter] > 200 | __throw_format_error(const char* __what) > | ~~~~~~~~~~~~^~~~~~ > > libstdc++-v3/ > * include/bits/c++config [!__cpp_exceptions] > (_GLIBCXX_THROW_OR_ABORT): Reference '_EXC'. > --- > libstdc++-v3/include/bits/c++config | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/libstdc++-v3/include/bits/c++config > b/libstdc++-v3/include/bits/c++config > index b0ca6579cfb..e9782c03ee2 100644 > --- a/libstdc++-v3/include/bits/c++config > +++ b/libstdc++-v3/include/bits/c++config > @@ -253,7 +253,7 @@ > # if __cpp_exceptions > # define _GLIBCXX_THROW_OR_ABORT(_EXC) (throw (_EXC)) > # else > -# define _GLIBCXX_THROW_OR_ABORT(_EXC) (__builtin_abort()) > +# define _GLIBCXX_THROW_OR_ABORT(_EXC) ((void) (_EXC), __builtin_abort())
We don't want to evaluate _EXC before aborting. There's no reason to e.g. concatenate strings and allocate memory to do so, or copy filesystem::path objects into a filesystem::filesystem_error that will never be thrown, or obtain a reference to an error_category. I don't think we want/need this at all, but it could be done like this if we need _EXC to be present but unused: # define _GLIBCXX_THROW_OR_ABORT(_EXC) (__builtin_abort(), (void)(_EXC))
