Standard library exception types are now constexpr-compatible. This includes std::logic_error, std::runtime_error, std::out_of_range, std::invalid_argument, std::bad_optional_access, std::bad_variant_access, std::bad_expected_access, std::format_error, and their related exception classes. Their constructors, destructors, and member functions are marked constexpr.

With constexpr exceptions enabled (P3068), code can throw and catch exceptions during constant evaluation. However, using standard exception types in such code was not possible because their constructors were not constexpr. This change enables standard exceptions types to be thrown and caught during compile-time evaluation.

#include <stdexcept>
#include <optional>

constexpr int safe_access(int index) {
    if (index < 0) {
        throw std::out_of_range("negative index");
    }
    return index;
}

constexpr int test() {
    try {
        return safe_access(-1);
    } catch (const std::out_of_range&) {
        return -1;
    }
}

static_assert(test() == -1);

int main() {}