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Re: [PATCH] PR libgcc/83112, Fix warnings on libgcc float128-ifunc.c
- From: Andreas Schwab <schwab at suse dot de>
- To: Segher Boessenkool <segher at kernel dot crashing dot org>
- Cc: Michael Meissner <meissner at linux dot vnet dot ibm dot com>, Martin Sebor <msebor at gmail dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>, David Edelsohn <dje dot gcc at gmail dot com>, Bill Schmidt <wschmidt at linux dot vnet dot ibm dot com>
- Date: Tue, 12 Dec 2017 18:18:21 +0100
- Subject: Re: [PATCH] PR libgcc/83112, Fix warnings on libgcc float128-ifunc.c
- Authentication-results: sourceware.org; auth=none
- References: <20171127192131.GA15914@ibm-tiger.the-meissners.org> <aabb7e7e-4678-f4a4-9240-6587438a0aeb@gmail.com> <20171127234009.GA28990@ibm-tiger.the-meissners.org> <20171130024250.GX10515@gate.crashing.org> <20171130205425.GA11524@ibm-tiger.the-meissners.org> <20171201054022.GA5348@ibm-tiger.the-meissners.org> <20171201235355.GL10515@gate.crashing.org> <20171211205750.GA16210@ibm-tiger.the-meissners.org> <20171212170455.GT10515@gate.crashing.org>
On Dez 12 2017, Segher Boessenkool <segher@kernel.crashing.org> wrote:
> On Mon, Dec 11, 2017 at 03:57:51PM -0500, Michael Meissner wrote:
>> > > +extern KCtype __divkc3 (KFtype, KFtype, KFtype, KFtype);
>> > > +
>> > > KCtype
>> > > __divkc3 (KFtype a, KFtype b, KFtype c, KFtype d)
>> > > {
>> >
>> > How does this warn? -Wmissing-declarations? Should this declaration be
>> > in a header then?
>>
>> The compiler creates the call to __mulkc3 and __divkc3, and internally it has
>> the appropriate prototype like it does for all built-in functions (in this
>> case, returning an _Float128 _Complex type, and taking 4 _Float128 arguments).
>>
>> So before adding ifunc support, we never noticed it didn't have a prototype,
>> because the compiler already has a prototype.
>
> I still don't get it. A function definition is also a declaration.
>
> Something very non-intuitive is happening?
`-Wmissing-prototypes (C and Objective-C only)'
Warn if a global function is defined without a previous prototype
declaration. This warning is issued even if the definition itself
provides a prototype.
Andreas.
--
Andreas Schwab, SUSE Labs, schwab@suse.de
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"And now for something completely different."