Re: [PATCH] PR libgcc/83112, Fix warnings on libgcc float128-ifunc.c

[Segher Boessenkool <segher@kernel.crashing.org>]

On Fri, Dec 01, 2017 at 12:40:22AM -0500, Michael Meissner wrote:
> After committing the previous patch, I noticed that it was now generating
> warnings for __{mul,div}kc3_{sw,hw} not having a prototype that I hadn't
> noticed during development of the patch.  This is due to the fact that before I
> added the ifunc support, it was only compiling __{mul,div}kc3, and those have
> built-in declarations.  I installed this patch as being obvious:
> 
> 2017-11-30  Michael Meissner  <meissner@linux.vnet.ibm.com>
> 
> 	* config/rs6000/_mulkc3.c (__mulkc3): Add forward declaration.
> 	* config/rs6000/_divkc3.c (__divkc3): Likewise.
> 
> Index: libgcc/config/rs6000/_divkc3.c
> ===================================================================
> --- libgcc/config/rs6000/_divkc3.c	(revision 255288)
> +++ libgcc/config/rs6000/_divkc3.c	(working copy)
> @@ -37,6 +37,8 @@ typedef __complex float KCtype __attribu
>  #define __divkc3 __divkc3_sw
>  #endif
>  
> +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?

A code comment explaining why you do a declaration for exactly the same
thing as there is two lines later would help; otherwise people will try
to delete it again :-)


Segher