https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115808
--- Comment #3 from linuxnyasha at tutanota dot com --- (In reply to Andrew Pinski from comment #1) > MSVC rejects this code: > ``` > <source>(46): error C3779: 'utempl::loopholes::Magic': a function that > returns 'auto' cannot be used before it is defined > <source>(6): note: see declaration of 'utempl::loopholes::Magic' > <source>(46): error C2062: type 'unknown-type' unexpected > > ``` > > > So I am suspecting this might be not valid code but no diagnostic required. On clang works
