Re: Suspicious warning in W64 build

[Richard Copley]

On 8 September 2017 at 21:17, Eli Zaretskii <address@hidden> wrote:
>> From: Richard Copley <address@hidden>
>> Date: Fri, 8 Sep 2017 20:31:08 +0100
>> Cc: Paul Eggert <address@hidden>, Angelo Graziosi <address@hidden>,
>>       Emacs Development <address@hidden>
>>
>> Would you mind also suppressing warnings from find-file-noselect
>> when called from autoload-find-generated-file, please, if you don't
>> object?
>
> Sorry, I'm not sure that's the right solution in that case.  We should
> try to understand why the problem happens in the first place.  E.g., I
> don't see it here (but I don't use MinGW64 or MSYS2).

Seriously (not being rude)? It seems a lot of work for not much
benefit. That conversion happens often, e.g., in normalize_filename.
And it's unlikely a warning from find_file_noselect there is ever
going to be helpful in catching a new bug.

>> "Crazy" was too strong (not to mention insensitive) a word to use,
>> but I still can't see that GCC is justified to warn when an
>> expression's value _might_ be out of range based on operand types;
>> taken to extremes that would rule out "alloca((size_t)n)". So either
>> I'm still missing something, or there's a GCC bug, or the compiler
>> correctly deduced that a negative number is passed in. I'm probably
>> still missing something.
>
> The only thing you might be missing is the fact that we passed the
> compiler the -Walloc-size-larger-than=9223372036854775807 option.

No, I don't think so. That's just the flag that enables that warning,
isn't it? I've read and re-read its documentation and I still don't
see why the warning is correct. The warning is intended for the case
when the argument is always out of range, if I understand correctly.