Improving -Wunused-member-function

[Nuno Lopes]

Hi,

Please find in attach a second version of the patch, which reuses the cache 
of defined records properly.
With this patch, -Wunused-member-function now flags unused private methods 
whenever the class is fully defined.
This patch does not attempt to fix false positives that were being triggered 
before in classes in anonymous namespaces.  I'll fix those afterwards.

OK to commit?

Thanks,
Nuno

----- Original Message ----- 
From: Nuno Lopes
Sent: Sunday, March 23, 2014 11:14 PM
Subject: Improving -Wunused-member-function


> Hi,
>
> I would like to improve -Wunused-member-function to detect unused private
> methods, similarly to how -Wunused-private-fields works.
> I think clang should be able to flag a method if 1) it is unused, 2) all 
> the
> methods of the class are defined in the TU, and 3) any of the following
> conditions holds:
> - The method is private.
> - The method is protected and the class is final.
> - The method is public and the class is in an anonymous namespace.
>
> I have a simple implementation in attach that can handle the first case
> (private methods) only.
> I'm not very happy with it, though. In particular I would like to move the
> logic somewhere else, so that we can reuse it from Codegen. And right now
> I'm not caching things properly.  Any suggestions to where this code
> belongs?  Should it go directly to Decl? (but that would imply adding a 
> few
> fields for cache purposes).
>
> Any comments and suggestions are welcomed!
>
> Thanks,
> Nuno
>
> P.S.: I run the attached patch over the LLVM codebase and I already fixed 
> a
> bunch of cases it detected (but left many still). So big code bases will
> certainly benefit from this analysis. Moreover, removing unused decls
> triggered more -Wunused-private-fields  warnings. 
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