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

From: "Russell King (Oracle)" <[email-masked]>
Date: Fri, 3 May 2024 09:18:00 +0100

On Fri, May 03, 2024 at 10:15:16AM +1000, Stephen Rothwell wrote:
> Hi all,
> 
> 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:

  CC      drivers/clk/clkdev.o
  AR      drivers/clk/built-in.a
  AR      drivers/built-in.a
  AR      built-in.a
  AR      vmlinux.a
  LD      vmlinux.o
  OBJCOPY modules.builtin.modinfo
  GEN     modules.builtin
  MODPOST Module.symvers
  UPD     include/generated/utsversion.h
  CC      init/version-timestamp.o
  LD      .tmp_vmlinux.kallsyms1
  NM      .tmp_vmlinux.kallsyms1.syms
  KSYMS   .tmp_vmlinux.kallsyms1.S
  AS      .tmp_vmlinux.kallsyms1.S
  LD      .tmp_vmlinux.kallsyms2
  NM      .tmp_vmlinux.kallsyms2.syms
  KSYMS   .tmp_vmlinux.kallsyms2.S
  AS      .tmp_vmlinux.kallsyms2.S
  LD      vmlinux
  NM      System.map

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.

-- 
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