[cfe-commits] [Patch] Warn about non-standard format strings (PR12017)

[Ted Kremenek]

On Feb 21, 2012, at 12:23 PM, Joerg Sonnenberger <joerg at britannica.bec.de> wrote:

>>> Do we really silently accept them?  Until very recently (a month ago?), we
>>> emitted:
>>> 
>>> t.c:4:12: warning: length modifier 'L' results in undefined behavior or no
>>>       effect with 'i' conversion specifier [-Wformat]
>>>   printf("%Li", (long long) 2);
>>>           ~^~
>>> 1 warning generated.
>>> 
>>> 
>>> Now I see that TOT doesn't warn here.  Is this accepted somewhere?  I see no
>>> test cases in clang/test that shows we should accept this.  Was this an
>>> intentional change, or a regression?
>> 
>> r148859 made them accepted about a month ago. Looks intentional to me :)
> 
> Which brings up the question, where is that documented? At least the
> Linux documentation is silent on this being valid.


According to PR 9466, this is a general GNU extension:

http://www.gnu.org/software/libc/manual/html_node/Integer-Conversions.html

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