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Re: PATCH RFC: -Wstrict-overflow, take 2
- From: Jonathan Lennox <lennox at cs dot columbia dot edu>
- To: Ian Lance Taylor <iant at google dot com>, gcc-patches at gcc dot gnu dot org
- Date: Fri, 16 Feb 2007 16:11:57 -0500
- Subject: Re: PATCH RFC: -Wstrict-overflow, take 2
- References: <m3hctwgi1d.fsf@localhost.localdomain>
Ian Lance Taylor <iant at google dot com> wrote:
> Here is a new version of my -Wstrict-overflow patch. This
> incorporates all the comments made on the first version.
> At -Wstrict-overflow=3 we get 31 warnings:
> ../../trunk/gcc/expmed.c:3485: warning: assuming signed overflow does not
> occur when changing X +- C1 cmp C2 to X cmp C1 +- C2
How hard would it be to change this diagnostic to print the actual values of
"X", "+-", "C1", "cmp", and "C2"?
For expmed.c:3485, for example, the warning would be
../../trunk/gcc/expmed.c:3485: warning: assuming signed overflow does not
occur when changing "size - 1 < 32" to "size < 32 + 1"
I think this would be much more accessible to people not versed in the
intricacies of compilers, and also make it much easier (as in this case) to
see at a glance if signed overflow could actually be a problem.
--
Jonathan Lennox
lennox at cs dot columbia dot edu