https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113099
--- Comment #3 from andysem at mail dot ru --- I think, a failing dynamic_cast would not be useful as this would make std::use_facet unusable with -fno-rtti. Re. ODR violation in the latest code, while it is true that the dynamic/static_cast is not reachable for the standard facets, it is still part of the function definition and the compiler is free to generate code that takes it into account. Note that the shortcuts for the standard facets are implemented with conditional if-constexpr, which will turn into regular ifs if libstdc++ is compiled in pre-C++17 mode. Which, I think, is the default, isn't it? I think, the ODR violation is still worth fixing.
