Build error with gcc 15.0 and kernel rt 5.10.233.rt125

Build error with gcc 15.0 and kernel rt 5.10.233.rt125

[Yann Collette]

Hello,

I met a build error while building the kernel rt 5.10.233-rt125 on 
Fedora rawhide with gcc-15.0.1.
It looks like gcc-15.0.1 switched to C23.

Here is the error message:

   CC      arch/x86/realmode/rm/wakemain.o
In file included from ./include/uapi/linux/posix_types.h:5,
                  from ./include/uapi/linux/types.h:14,
                  from ./include/linux/types.h:6,
                  from arch/x86/realmode/rm/wakeup.h:11,
                  from arch/x86/realmode/rm/wakemain.c:2:
./include/linux/stddef.h:11:9: error: cannot use keyword ‘false’ as 
enumeration constant
    11 |         false   = 0,
       |         ^~~~~
./include/linux/stddef.h:11:9: note: ‘false’ is a keyword with 
‘-std=c23’ onwards
./include/linux/types.h:30:33: error: ‘bool’ cannot be defined via 
‘typedef’
    30 | typedef _Bool                   bool;
       |                                 ^~~~
./include/linux/types.h:30:33: note: ‘bool’ is a keyword with 
‘-std=c23’ onwards
./include/linux/types.h:30:1: warning: useless type name in empty 
declaration
    30 | typedef _Bool                   bool;
       | ^~~~~~~
make[3]: *** [scripts/Makefile.build:286: 
arch/x86/realmode/rm/wakemain.o] Error 1
make[2]: *** [arch/x86/realmode/Makefile:23: 
arch/x86/realmode/rm/realmode.bin] Error 2
make[1]: *** [scripts/Makefile.build:503: arch/x86/realmode] Error 2
make[1]: *** Waiting for unfinished jobs....

Best regards,

Yann

Re: Build error with gcc 15.0 and kernel rt 5.10.233.rt125

[Sebastian Andrzej Siewior]

On 2025-01-31 07:33:17 [+0100], Yann Collette wrote:
> Hello,
> 
> I met a build error while building the kernel rt 5.10.233-rt125 on Fedora
> rawhide with gcc-15.0.1.
> It looks like gcc-15.0.1 switched to C23.

This should help
	https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?id=ee2ab467bddfb2d7f68d996dbab94d7b88f8eaf7

But I would wait until it gets to the v5.10.X series. This is not an
RT-only problem.

Sebastian