Re: [PATCH 1/2] Kbuild: enable -fms-extensions

[Dave Kleikamp <dave.kleikamp@oracle.com>]

On 10/23/25 7:40AM, Nathan Chancellor wrote:
> On Wed, Oct 22, 2025 at 11:11:38PM +0200, Nathan Chancellor wrote:
> ...
>>>>> +# Allow including a tagged struct or union anonymously in another struct/union.
>>>>> +KBUILD_CFLAGS += -fms-extensions
> ...
>> I have tentatively applied this to kbuild-next so that it can spend most
>> of the cycle in -next to try and catch all potential problems.
> 
> One side effect that has been found in my testing so far is clang's
> '-fms-extensions' turns '_inline' into a keyword, which breaks fs/jfs:
> 
>    In file included from fs/jfs/jfs_unicode.c:8:
>    fs/jfs/jfs_incore.h:86:13: error: type name does not allow function specifier to be specified
>       86 |                                         unchar _inline[128];
>          |                                                ^
>    fs/jfs/jfs_incore.h:86:20: error: expected member name or ';' after declaration specifiers
>       86 |                                         unchar _inline[128];
>          |                                         ~~~~~~~~~~~~~~^
> 
> There appear to be other similar keywords (ones with KEYMS in the linke
> below) but my personal distribution configuration does not show any
> instances in the build where they matter (I did not test allmodconfig
> yet).
> 
>    https://github.com/llvm/llvm-project/blob/249883d0c5883996bed038cd82a8999f342994c9/clang/include/clang/Basic/TokenKinds.def#L744-L794
> 
> Something like this is all it takes to resolve the issue, so I will send
> a patch for formal review/acking but I wanted to bring it up ahead of
> time in case this is unpalpable and we should throw these changes out of
> -next instead of forward fixing.

I'm on vacation now, so I may be slow to respond to a future patch, so 
I'll go ahead and give you my ack to this.

Acked-by: Dave Kleikamp <dave.kleikamp@oracle.com>

> 
> Cheers,
> Nathan
> 
> diff --git a/fs/jfs/jfs_incore.h b/fs/jfs/jfs_incore.h
> index 10934f9a11be..5aaafedb8fbc 100644
> --- a/fs/jfs/jfs_incore.h
> +++ b/fs/jfs/jfs_incore.h
> @@ -76,14 +76,14 @@ struct jfs_inode_info {
>   		struct {
>   			unchar _unused[16];	/* 16: */
>   			dxd_t _dxd;		/* 16: */
> -			/* _inline may overflow into _inline_ea when needed */
> +			/* _inline_sym may overflow into _inline_ea when needed */
>   			/* _inline_ea may overlay the last part of
>   			 * file._xtroot if maxentry = XTROOTINITSLOT
>   			 */
>   			union {
>   				struct {
>   					/* 128: inline symlink */
> -					unchar _inline[128];
> +					unchar _inline_sym[128];
>   					/* 128: inline extended attr */
>   					unchar _inline_ea[128];
>   				};
> @@ -101,7 +101,7 @@ struct jfs_inode_info {
>   #define i_imap u.file._imap
>   #define i_dirtable u.dir._table
>   #define i_dtroot u.dir._dtroot
> -#define i_inline u.link._inline
> +#define i_inline u.link._inline_sym
>   #define i_inline_ea u.link._inline_ea
>   #define i_inline_all u.link._inline_all
>