https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110211
Johel Ernesto Guerrero Peña <johelegp at gmail dot com> changed: What |Removed |Added ---------------------------------------------------------------------------- Known to fail| |9.5.0 --- Comment #1 from Johel Ernesto Guerrero Peña <johelegp at gmail dot com> --- Simplified: - GCC 9.5 <https://compiler-explorer.com/z/PTr9Tbe5G>. - GCC trunk <https://compiler-explorer.com/z/5cbEMvEvo>. ```C++ int main() { [](auto x) -> decltype([&](auto) {}(x)) {}(0); } ``` With this, MSVC fails. Apparently, rather than a hard error, it fails OR. That must be why it passed before.