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From: Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups: comp.lang.c
Subject: Re: tcc - first impression. Was: Baby X is bor nagain
Date: Tue, 02 Jul 2024 06:47:35 -0700
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Michael S <already5chosen@yahoo.com> writes:

> On Mon, 01 Jul 2024 14:48:30 -0700
> Keith Thompson <Keith.S.Thompson+u@gmail.com> wrote:
>
>> Michael S <already5chosen@yahoo.com> writes:
>> [...]
>>> 4.2.  Code like below does not compile.  I don't know whether it is
>>> legal 'C' or not,
>>> but gcc, clang and MSVC compilers accept it o.k.
>>> label:int bar;
>>
>> That's a syntax error in versions of C up to and including C17.  C23
>> allows labels on declarations. [...]
>
> Now I paid attention that my statement above is incorrect:  clang does
> *not* accept it.
> gcc accepts it, for all supported standards, but with -Wpedantic
> it issues the warning for all standards except c2x.
> MSVC (17 and 19, but not 13) accepts it and issues no warning even with
> maximal warning level.
>
> clang and tcc are right.  I find no advantages in this sort of rightness.

Is your objection to a diagnostic message being issued, or is
your objection to the construct causing the compilation to fail?

I would call what the more recent MSVC versions do as being
*wrong*.  The C standard requires a diagnostic.

I would not call what clang and tcc do as being right.  Their
behavior conforms to the C standard, but giving an unavoidable
error is kind of obnoxious.

The reported behavior for gcc -pedantic is okay.  It would be
nice if there were a separate option to allow the non-standard
labels to be accepted without giving a warning.  Also it would
be better if -std=cNN implied -pedantic (presumably with a way
to change that, selectively if possible);  historically that
choice might have been okay, but for at least the last 15 years
it has been a disservice to the C community.  I should note
specifically that it is -pedantic that should be implied, and
not -pedantic-error.

More generally, the default behavior for any non-conforming but
often used construct should be a warning, not an error (unless of
course -Werror has been specified).  I understand the motivation
to give an error in the case of a syntax violation, but forcing
any syntax violation to be an error is still a poor choice, not
just for the compiler but also for the C community generally.

Just my opinions, in case that needs saying.