PR c/53066 Wshadow should not warn for shadowing an extern function

[Manuel López-Ibáñez]

On 25 April 2012 13:54, Joseph S. Myers <joseph@codesourcery.com> wrote:
> On Wed, 25 Apr 2012, Manuel López-Ibáñez wrote:
>
>> On 25 April 2012 00:01, Joseph S. Myers <joseph@codesourcery.com> wrote:
>> > On Sun, 22 Apr 2012, Manuel López-Ibáñez wrote:
>> >
>> >> Wshadow warns whenever any declaration shadows a global function
>> >> declaration. This is almost always noise, since most (always?) of the
>> >> time one cannot mistakenly replace a function by another variable. The
>> >> false positives are too common (Linus mentions using the name 'index'
>> >> when including string.h).
>> >
>> > I think the correct rule would be: warn if a variable *with
>> > pointer-to-function type* shadows a function, and warn if a nested
>> > function shadows another function, but don't warn for variables shadowing
>> > functions if the variable has any other type (because if the variable has
>> > some type that isn't a pointer-to-function, no confusion is likely without
>> > another error being given).
>>
>> Right. How does one check that a decl is a nested function?
>
> I think you should check if the decl has function type or pointer to
> function type.  (Nested functions are simply I think the only valid case
> where you can end up with one function shadowing another; "has function
> type" is the logical check rather than "is a nested function".)

Like so? Bootstrapped and regression tested on x86_64-linux-gnu.

OK?

2012-10-27  Manuel López-Ibáñez  <manu@gcc.gnu.org>

	PR c/53066
gcc/
	* c/c-decl.c (warn_if_shadowing): Do not warn if a variable
	shadows a function, unless the variable is a function or a
	pointer-to-function.
	* tree.h (FUNCTION_POINTER_TYPE_P): New.
testsuite/
	* gcc.dg/Wshadow-4.c: New.
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