https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110204
Bug ID: 110204
Summary: Suspicous warning when compiling ranges-v3 using GCC
trunk (iteration 9223372036854775807 invokes undefined
behavior)
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: jun at junz dot org
Target Milestone: ---
Given code:
#include <vector>
#include <map>
#include <range/v3/all.hpp>
std::map<int, int> m;
std::vector<int> foo() {
return ranges::to<std::vector>(m | ranges::views::keys);
}
GCC trunk reports:
/opt/compiler-explorer/gcc-trunk-20230610/include/c++/14.0.0/bits/stl_iterator_base_funcs.h:175:9:
warning: iteration 9223372036854775807 invokes undefined behavior
[-Waggressive-loop-optimizations]
175 | while (__n--)
| ^~~~~
/opt/compiler-explorer/gcc-trunk-20230610/include/c++/14.0.0/bits/stl_iterator_base_funcs.h:175:9:
note: within this loop
while Clang and GCC 13 both say OK. I think this is a regression.
goldbolt link: https://godbolt.org/z/W33aMqr5c
