[cfe-dev] Is it possible to avoid FP when there is #ifdef in the code

[Vedant Kumar via cfe-dev]

I don't think it's fair to call this a false positive, unless the "XYZ" macro is defined.

The analyzer has to run the preprocessor to handle basic things like #include. Modifying the checker to do what you propose would require going from the AST -> source code, scanning for a preprocessor command, altering it, re-parsing it, re-running the checker etc.

It would be easier to add a line like "(void) x;" to suppress the warning.

best
vedant

On Aug 26, 2015, at 1:35 AM, Daniel Marjamäki via cfe-dev <cfe-dev at lists.llvm.org> wrote:

> 
> Hello!
> 
> Sometimes there are false positives when #ifdef is used and for instance usage of some macro/parameter is hidden.
> 
> I am running Clang in a project where we get several such FPs.
> 
> Example code:
> 
> void f(int x) {
>    // ..code..
> #ifdef XYZ
>    dostuff(x);
> #endif
>    // ..code..
> }
> 
> Warning:
> 1.c:1:12: warning: unused parameter 'x' [-Wunused-parameter]
> void f(int x) {
>           ^
> 
> 
> Is there anything that can be done in the unused-parameter checker to prevent such FP?
> 
> For instance.. is it possible to see if there was a #ifdef in a function and disable the warning in that function.
> 
> Best regards,
> Daniel Marjamäki
> 
> 
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