[Bug c++/109554] Compiler generates incorrect code when the function declared with returned parameterm but no 'return' in its body

[xry111 at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109554

--- Comment #2 from Xi Ruoyao <xry111 at gcc dot gnu.org> ---
And it's clearly documented in https://gcc.gnu.org/gcc-8/changes.html:

Flowing off the end of a non-void function is considered unreachable and may be
subject to optimization on that basis. As a result of this change,
-Wreturn-type warnings are enabled by default for C++.

If you insist on ignoring the -Wreturn-type warning, you are doing things
wrong.