Subject: Re: linux-next: build failure after merge of the arm tree

From: Stephen Rothwell <[email-masked]>
Date: Fri, 3 May 2024 22:08:26 +1000

Hi Russell,

On Fri, 3 May 2024 09:18:00 +0100 "Russell King (Oracle)" <[email-masked]> wrote:
>
> On Fri, May 03, 2024 at 10:15:16AM +1000, Stephen Rothwell wrote:
> > 
> > After merging the arm tree, today's linux-next build (x86_64 allmodconfig)
> > failed like this:
> > 
> > drivers/clk/clkdev.c: In function 'vclkdev_alloc':
> > drivers/clk/clkdev.c:195:16: error: assignment to '__va_list_tag (*)[1]' from incompatible pointer type '__va_list_tag **' [-Werror=incompatible-pointer-types]
> >   195 |         fmt.va = &ap;
> >       |                ^
> > cc1: all warnings being treated as errors  
> 
> This builds perfectly fine for me - this is on debian stable with
> arm-linux-gnueabihf-gcc (Debian 10.2.1-6) 10.2.1 20210110:
> 
> No warnings, no errors.
> 
> va_format is defined as:
> 
> struct va_format {
>         const char *fmt;
>         va_list *va;
> };
> 
> and what we have here is a "va_list ap".
> 
> Therefore, the assignment:
> 
>         fmt.va = &ap;
> 
> is correct.
> 
> What certainly won't work is:
> 
> 	fmt.va = ap;
> 
> and there aren't any other reasonable alternatives.
> 
> My conclusion: your compiler is being stupid.

Definitely possible.  My build is an x86_64 allmodconfig cross build
hosted on PowerPC64LE.

$ x86_64-linux-gnu-gcc --version
x86_64-linux-gnu-gcc (Debian 13.2.0-7) 13.2.0

It still fails for me even just building your tree.  :-(

And if I revert commit 5d998425e37b it does not fail (of course).

-- 
Cheers,
Stephen Rothwell