[cfe-dev] Warnings not raised from a macro: -Wundefined-bool-conversion/-Wtautological-undefined-compare

[Alexander Kornienko]

+curdeius at gmail.com

I found this thread while searching for something else in the list archive.

This report would definitely be more visible on llvm.org/bugs, I've filed
it as llvm.org/PR22785.

The issue has nothing to do with the Clang's treatment of macros
in -Wundefined-bool-conversion/-Wtautological-undefined-compare
diagnostics. It's just an over-eager attempt to avoid breaking the code by
messing with macros.

Marek (cc-ed here) is the author of the corresponding check. Maybe he'll be
interested in fixing the issue.

-- Alex

On Mon, Nov 10, 2014 at 1:59 PM, miroslav.fontan <
miroslav.fontan at wincor-nixdorf.cz> wrote:

> Hi,
>
> Thanks for the -save-temps hint, it helps with this particular issue,
> unfortunatelly it does not solve the cause of the problem.
>
> I guess that Clang-based tools inherit the same macro treatment from clang
> parser and give an inaccurate results.
>
> For example this code fragment is handled incorrectly by command:
> clang-tidy
> -check=-*,readability-braces-around-statements -fix
>
> #define MACRO_1 i++
> #define MACRO_2
>
> void test(int i)
> {
>         if( i % 3) i--; // OK
>         else if( i % 2) MACRO_1; // KO, no braces
>         else MACRO_2; // OK
> }
>
> Maybe I am stubborn, I still think that preprocess step should be made
> completely before the next steps.
>
> Best regards
>
> Mira
>
>
> > -----Original Message-----
> > From: cfe-dev-bounces at cs.uiuc.edu [mailto:cfe-dev-bounces at cs.uiuc.edu]
> > On Behalf Of Joerg Sonnenberger
> > Sent: Wednesday, November 05, 2014 12:20 PM
> > To: cfe-dev at cs.uiuc.edu
> > Subject: Re: [cfe-dev] Warnings not raised from a macro: -Wundefined-
> > bool-conversion/-Wtautological-undefined-compare
> >
> > On Wed, Nov 05, 2014 at 11:58:55AM +0100, miroslav.fontan wrote:
> > > I think Martin is right. Preprocessor is only textual replacement,
> > > compiler should not know about this step and compiles code resulting
> > > from preprocess step.
> >
> > A lot of people disagree. If you want to force it to give all warnings,
> > use -save-temps.
> >
> > Joerg
> > _______________________________________________
> > cfe-dev mailing list
> > cfe-dev at cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/cfe-dev
>
>
> _______________________________________________
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>
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