[PATCH] c++: Add std::to_underlying to the set of stdlib functions that are always folded

[Jonathan Wakely]

On Mon, 12 May 2025 at 21:35, Ville Voutilainen
<ville.voutilainen@gmail.com> wrote:
>
> This function is yet another stdlib function that is just a simple
> cast, so having
> it appear while debugging is arguably not useful. So add it to the
> existing handling
> that always-folds some stdlib functions.
>
> Add std::to_underlying to the set of stdlib functions that are always folded
>
> gcc/cp/ChangeLog:
>         * cp-gimplify.cc (cp_fold): Add to_underlying.
>
> gcc/testsuite/ChangeLog:
>         * g++.dg/opt/pr96780_cpp23.C: New.
>
> libstdc++/ChangeLog:
>         * include/std/utility (to_underlying): Add the
> __always_inline__ attribute.

Yes, this is just a simple cast like move and forward are.

The library part is OK.