[Bug middle-end/48814] [4.5/4.6/4.7 Regression] Incorrect scalar increment result

nmm1 at cam dot ac.uk gcc-bugzilla@gcc.gnu.org
Fri Mar 15 23:21:00 GMT 2013


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48814

Nick Maclaren <nmm1 at cam dot ac.uk> changed:

           What    |Removed                     |Added
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                 CC|                            |nmm1 at cam dot ac.uk

--- Comment #15 from Nick Maclaren <nmm1 at cam dot ac.uk> 2013-03-15 23:20:56 UTC ---
I must correct some of the statements here.  This is not a bug, and the
intent of WG14 during the standardisation of C90 was that this should be
undefined behaviour.  This point was raised explicitly - unfortunately,
those of us who wanted this area to be better specified did not
prevail:-(

This is a CHANGE in the C language introduced by C 2011.  gcc may wish
to adopt that, but that is not the same as saying this is a bug.  As
it merely degrades optimisation and does not break any working programs,
it is not a major matter.

The only reason that I am posting this after the decision has been taken
is that there are other changes introduced by C11 that may not be so
benign.  There are many less than in C99, but still quite a lot.  This
should not be used as precedent.



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