[cfe-commits] r56843 - in /cfe/trunk: include/clang/Basic/DiagnosticKinds.def lib/Sema/Sema.h lib/Sema/SemaDeclObjC.cpp lib/Sema/SemaExprObjC.cpp test/SemaObjC/method-lookup-3.m

[Daniel Dunbar]

Hi Steve,

Thanks for fixing this. Now that I have been using it for a little while I
have noticed a few inconsistencies that raise some questions.

On Tue, Sep 30, 2008 at 7:38 AM, Steve Naroff <snaroff at apple.com> wrote:
> +  if (MethList.Method && MethList.Next) {
> +    Diag(R.getBegin(), diag::warn_multiple_method_decl, Sel.getName(), R);
> +    Diag(MethList.Method->getLocStart(), diag::warn_using_decl,
> +         MethList.Method->getSourceRange());
> +    for (ObjCMethodList *Next = MethList.Next; Next; Next = Next->Next)
> +      Diag(Next->Method->getLocStart(), diag::warn_also_found_decl,
> +           Next->Method->getSourceRange());
> +  }

One problem here is that the 2nd and subsequent locations may be inside of
system headers. This leads to confusing error messages since they end up
getting suppressed and it isn't possible to tell the source of the conflict. I'm
wondering if there is an easy fix for this, or if we should try to
solve the "multipart"
error message problem more generally.

This also depends on whether we should suppress this warning for
conflict arising
from system headers. The right behavior may depend on whether the signature
we end up using comes from a system header or not.

> +    // FIXME: consider using LookupInstanceMethodInGlobalPool, since it will be
> +    // faster than the following method (which can do *many* linear searches).
> +    // The idea is to add class info to InstanceMethodPool.

I think we need to do this. Consider the following code
--
@interface A
+(void) foo;
@end
@interface B
+(int) foo;
@end

void f0(id x) {
  int i = [x foo];
}
--
which clang currently rejects (gcc emits the multiple methods warnings).

Finally, it appears the gcc is promiscuously accepting method conflicts for
certain types. For example:
--
typedef struct s0 T0;
typedef struct s1 T1;

@interface A
+(T0*) foo;
@end
@interface B
+(T1*) foo;
@end

void f0(id x) {
  void *bar = [x foo];
}
--

Let me know if you would prefer me to file bugs for any of these.

 - Daniel