[Bug c++/102613] [C++23] P2246R1 - Character encoding of diagnostic text

["jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102613

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org,
                   |                            |jason at gcc dot gnu.org

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Is there anything we need to do here?
From what I can see, e.g. for static assertions which is one of the two changed
points
we reencode the message from -finput-charset= charset if supplied to UTF-8 and
then emit the UTF-8 chars to the terminal regardless of locale's charset
unobfuscated, so say given:
static_assert (false, "��c");
and -finput-charset=ISO-8859-1
00.C:1:16: error: static assertion failed: áæc
    1 | static_assert (false, "áæc");
      |                ^~~~~
is emitted, while without that -finput-charset= (i.e. when it is invalid
UTF-8), we emit
00.C:1:16: error: static assertion failed: ��c
    1 | static_assert (false, "��c");
      |                ^~~~~
On valid UTF-8 emoji:
static_assert (false, "😀");
we emit
01.C:1:16: error: static assertion failed: 😀
    1 | static_assert (false, "😀");
      |                ^~~~~
and with -finput-charset=ISO-8859-1
01.C:1:16: error: static assertion failed: ð
    1 | static_assert (false, "ð");
      |                ^~~~~
Not really sure what to do for our testsuite for this though, because while we
can use -finput-charset= in dg-options, we have no control on what the pseudo
terminal encoding actually is.