https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110890
Bug ID: 110890
Summary: std::is_array and std::extent incorrectly choose a
partial specialization when the size of an array
exceeds INT32_MAX
Product: gcc
Version: 9.4.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: y1079700998 at gmail dot com
Target Milestone: ---
#include <type_traits>
#include <cstdint>
#include <iostream>
using T1 = char[1ul + INT32_MAX];
int main() {
std::cout << std::is_array_v<T1> << '\n';
std::cout << std::extent_v<T1, 0> << '\n';
}
When compiled with `g++ array_test.cpp -g -std=c++17 -Wall -Wextra
-fno-strict-aliasing -fwrapv -fno-aggressive-loop-optimizations
-fsanitize=undefined`, this script generates a result of "0 0". This behavior
was also observed with GCC 13.2 on godbolt.
When using clang++(tested with 10.0.0), however, the script generates the
expected result of "1 2147483648".
I discovered this behavior while performing some edge testing. It's probably
very rare to have an array of such a size in a real application.
