OK.
On Sat, Nov 19, 2016 at 6:11 AM, Bernd Edlinger
<bernd.edlin...@hotmail.de> wrote:
> Hi,
>
> On 11/18/16 22:19, Jason Merrill wrote:
>> On 11/05/2016 12:44 PM, Bernd Edlinger wrote:
>>> + warning_at (DECL_SOURCE_LOCATION (newdecl), 0,
>>> + "declaration of %q+#D conflicts with built-in "
>>> + "declaration %q#D", newdecl, olddecl);
>>
>> There needs to be a way to disable this warning, even if it's enabled by
>> default.
>>
>>> - TREE_NOTHROW (olddecl) = 0;
>>> + TREE_NOTHROW (olddecl) = TREE_NOTHROW (newdecl);
>>
>> I still think a better fix would be to add a copy of TREE_NOTHROW to the
>> else block of the if (types_match), to go with the existing copies of
>> TREE_READONLY and TREE_THIS_VOLATILE.
>>
>
>
> I changed the patch as requested. I think meanwhile that this else
> block does only handle a built-in function with different signature.
>
> I have now changed also the C front end to emit the warning with the new
> default-enabled -Wbuiltin-declaration-mismatch.
>
> When I looked at the c-decl.c code, I saw there are effectively two
> warnings, one for a function that does not match the builtin signature,
> and another for a global variable that has the the name of a built-in.
>
> like:
> test.c
> int printf;
>
> gives warning:
> test.c:1:5: warning: built-in function 'printf' declared as non-function
> int printf;
>
>
> the same in C++ gives nothing.
>
> That is because of this in duplicate_decls:
>
> if (TREE_CODE (newdecl) != FUNCTION_DECL)
> {
> /* Avoid warnings redeclaring built-ins which have not been
> explicitly declared. */
> if (DECL_ANTICIPATED (olddecl))
> return NULL_TREE;
>
> That is from gcc3.1 in 2002 a rather radical patch I would say.
>
> I left the warning for declaring a variable with the name of built-in
> function for next time, maybe...
>
>
> Bootstrapped and reg-tested on x86_64-pc-linux-gnu.
> Is it OK for trunk?
>
>
> Thanks
> Bernd.
