https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62096
Bug ID: 62096 Summary: unexpected warning overflow in implicit constant conversion Product: gcc Version: 4.9.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: travis.vitek at roguewave dot com The following test case generates a an unexpected warning. [vitek@sidewinder] 350 % gcc -v Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/amd/packages/mdx/redhat/compilers/gcc-4.9.0/bin/../libexec/gcc/x86_64-unknown-linux-gnu/4.9.0/lto-wrapper Target: x86_64-unknown-linux-gnu Configured with: ../gcc-4.9.0/configure --prefix=/build/gcc-4.9.0 --enable-languages=c,c++ Thread model: posix gcc version 4.9.0 (GCC) [vitek@sidewinder] 351 % cat t.cpp enum E { E_val = 1, }; inline constexpr E operator~(E e) { return E(~static_cast<int>(e)); } int main() { int val = ~E_val; (void) val; } [vitek@sidewinder] 352 % g++ --pedantic -std=c++11 -c ./t.cpp ./t.cpp: In function 'int main()': ./t.cpp:12:16: warning: overflow in implicit constant conversion [-Woverflow] int val = ~E_val; ^ [vitek@sidewinder] 353 % The issue seems to be related to the function being constexpr and the type of the destination being int. If I remove the constexpr or change the destination type (to long long or E), the warning goes away.