https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119150
Bug ID: 119150
Summary: Optimization causes function call arguments to
consteval functions to not be manifestly
constant-evaluated
Product: gcc
Version: 14.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: aapomeranz at yahoo dot com
Target Milestone: ---
#include <iostream>
auto consteval CONSTEVAL(auto x)
{
return x;
}
constexpr bool isconstant()
{
return std::is_constant_evaluated();
}
int main()
{
// Tested via godbolt.org using the following compilers/flags:
// GCC x86-64 -std=c++20 (13.3.0, 14.1.0, and 15.0.1 20250306)
// Clang x86-64 -std=c++20 (head)
// MSVC x64 /std:c++20 (head)
// Working case:
// GCC (all tested versions), Clang, MSVC: prints 1
constexpr int n { CONSTEVAL(isconstant()) };
std::cout << n << '\n';
// Broken case:
// Clang and MSVC: prints 1
// GCC: -Ox (when x == 0) prints 1 on GCC (all tested versions)
// GCC: -Ox (when x != 0) prints 1 on GCC 13.3.0
// GCC: -Ox (when x != 0) prints 0 on GCC 14.1.0 and 15.0.1 20250306
std::cout << CONSTEVAL(isconstant()) << '\n';
return 0;
}
