https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97665
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |jakub at gcc dot gnu.org
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
You can do Foo foo = Foo(); and it compiles. clang++ rejects it too:
error: constexpr union constructor that does not initialize any member is a
C++20 extension [-Werror,-Wc++20-extensions]
though only with -pedantic-errors.
But g++ rejects it even in -std=c++20 mode:
pr97665.C:15:13: error: ‘V{U [1]{U()}}’ is not a constant expression
15 | constexpr V v;
| ^
pr97665.C:15:13: error: ‘V()’ is not a constant expression because it refers to
an incompletely initialized variable
