https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77875
--- Comment #3 from Lénárd Szolnoki <leni536 at gmail dot com> ---
A more worrisome example presumably for this same bug, it's a miscompilation:
template <typename T>
decltype(auto) as_const(T& t) {
using const_ref = const T&;
return const_ref{t};
}
int main() {
int i = 42;
return as_const(i);
}
$ g++ -std=c++17 -O0 -fsanitize=undefined -Wall -pedantic main.cpp && ./a.out
main.cpp: In instantiation of 'decltype(auto) as_const(T&) [with T = int]':
main.cpp:9:22: required from here
main.cpp:4:23: warning: returning reference to temporary [-Wreturn-local-addr]
return const_ref{t};
^
main.cpp:4:23: runtime error: reference binding to null pointer of type 'const
int'
main.cpp:9:22: runtime error: load of null pointer of type 'const int'
bash: line 7: 802 Segmentation fault (core dumped) ./a.out
An UB is added where should be none.
