Package: libstdc++6
Version: 13.2.0-9
Streaming a negative NaN float produces "-nan" with g++ -O0 and "nan"
with g++ -O1 or above:
$ cat >mwe.cc <<EOF
> // Copyright 2023 Google LLC
> // SPDX-License-Identifier: Apache-2.0
>
> #include <bit>
> #include <iostream>
>
> int main() { std::cerr << std::bit_cast<float>(0xfff80000) << '\n'; }
> EOF
$ g++ -std=c++20 -O0 mwe.cc && ./a.out
nan
$ g++ -std=c++20 -O1 mwe.cc && ./a.out
-nan
$ clang++ -std=c++20 -O0 mwe.cc && ./a.out
nan
$ clang++ -std=c++20 -O1 mwe.cc && ./a.out
-nan
For comparison, on amd64, this program always produces "-nan",
regardless of optimization level.
Tested with g++-13 13.2.0-9 and clang-16 1:16.0.6-19.
