[Bug c/64440] -Wdiv-by-zero false negative on const variables

["mpolacek at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64440

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |mpolacek at gcc dot gnu.org

--- Comment #4 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
(In reply to Manuel López-Ibáñez from comment #3)
> (In reply to Chengnian Sun from comment #2)
> > Thanks for your reply. It seems GCC sometimes does consider "const int" for
> > other types of warnings (but not for -Wdiv-by-zero). See the following, with
> > -O3, GCC warns that the left shift count is negative.  
> > 
> 
> I wonder how this happens? The warning is still given by the FE!

By using decl_constant_value_for_optimization.
>From gcc-bugs-return-472320-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Tue Jan 06 15:38:56 2015
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From: "maurits.de.jong at ericsson dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c/64509] _Generic throws error in unselected generic association
Date: Tue, 06 Jan 2015 15:38:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idd509

--- Comment #2 from Martien de Jong <maurits.de.jong at ericsson dot com> ---
That's just rephrasing my bugreport. The question is, should it type check
while parsing an expression that may not be realized? The entire idea of
switching on a type is to prevent and fix type errors, no?