Re: More C type errors by default for GCC 14

[Eli Schwartz <eschwartz93@gmail.com>]

On 5/12/23 8:45 PM, Po Lu wrote:
> Gabriel Ravier <gabravier@gmail.com> writes:
> 
>> ...You're joking, right ? You can't possibly be seriously arguing
>> this, you have to be kidding... right ?
> 
> No, I'm not.  The meaning of a variable declaration with only a storage
> class specifier is extremely clear: the type of the variable is `int'.
> There's absolutely nothing ambiguous about it whatsoever:


Quoting my previous reply on the topic.

Until everyone is on the same page as you about whether these are GNUC
extensions, this conversation will go nowhere.

You are of the opinion that "GCC currently behaves a certain way when
compiling the code" means that the behavior is documented and specified
as a "C Extension" for the GNUC language dialect.

You've provided some excuses like "C++ is a valid language for writing
documentation in, and the HTML docs are lacking", but your arguments are
not convincing.

GCC has formal documentation. It is written in HTML. If it is lacking,
then the only valid move is to improve the HTML documentation and then
abide by it. In the absence of documentation, all behavior is, well,
"undocumented", which ***definitely*** means it isn't a formal GNUC
language dialect extension.

You can stop arguing your opinions based on what running gcc or g++
produces in the form of machine code. What gcc or g++ produces in the
form of machine code is not guaranteed even across bugfix releases --
your only guarantee is that if it is documented in the ISO standards
documents or in the GCC html manual, the produced machine code shall be
in accordance with what the documentation says it shall do.

Undefined and undocumented behavior is not a language extension. It is
undefined and undocumented behavior. You may feel free to take an exact
GCC release (source or binary), analyze it, reverse-engineer it, or
verify that it does what you want it to do, and then trust that those
undefined and undocumented behaviors are ***benevolent***, but that
doesn't cause it to be defined and documented, and your trust will, if
you are wise, depend on you pinning an exact source code commit of the
compiler. Do not depend on bugfix releases of GCC to preserve your
undocumented semantics. They may or they may not, but if they don't,
it's not a GCC bug, because it is ***undocumented***.

...

So in answer to your question, the meaning of such a variable
declaration is very much unclear -- C specifies one thing, GNUC doesn't
specify *anything*, and actually executing the gcc compiler frontend
tool will do... something.


-- 
Eli Schwartz