[Bug middle-end/36166] Use of the 'nonnull' attribute breaks code

["pgut001 at cs dot auckland dot ac dot nz" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #5 from pgut001 at cs dot auckland dot ac dot nz  2008-06-10 09:15 -------
>Think printf with %s where it is supplied with a NULL argument or puts 
>with a NULL argument.

Sure, I understand how that part of it works, but gcc doesn't just use it for
that, it applies two often mutually exclusive interpretations to the same
attribute.  Warning about inadvertent use of NULL is useful for developers, so
there's a temptation to annotate code with it to warn at compile time of errors
(and that seems to be the intended use of stdc_nonnull).  However the opposite
interpretation of the attribute is that if you do inadvertently pass a NULL
pointer to annotated code, gcc may not warn about it but will cause your code
to crash.  The single attribute shouldn't be used to perform two mutually
exclusive (and in one case, dangerous) actions, it's like storing rat poison in
a fruit juice bottle...


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36166