[PATCH v2] nptl: Check alignment of pthread structs

[Yury Khrustalev]

On Wed, Nov 19, 2025 at 04:45:36PM +0000, Wilco Dijkstra wrote:
> 
> Report assertion failure if the alignment of external pthread structs
> is lower than the internal version. This triggers on type mismatches like
> in BZ #33632.

LGTM. Thanks!

Reviewed-by: Yury Khrustalev <yury.khrustalev@arm.com>

> ---
> 
> diff --git a/sysdeps/nptl/pthreadP.h b/sysdeps/nptl/pthreadP.h
> index 3c9a14c3d6f8b3eb076be3495bb2222ff0dc2aad..f98cdf4769bcfe320117c6dcefb11a5a9ba0e7a6 100644
> --- a/sysdeps/nptl/pthreadP.h
> +++ b/sysdeps/nptl/pthreadP.h
> @@ -714,9 +714,11 @@ check_stacksize_attr (size_t st)
>    _Static_assert (sizeof (type) == size,				\
>  		  "sizeof (" #type ") != " #size)
>  
> -#define ASSERT_PTHREAD_INTERNAL_SIZE(type, internal) 			\
> -  _Static_assert (sizeof ((type) { { 0 } }).__size >= sizeof (internal),\
> -		  "sizeof (" #type ".__size) < sizeof (" #internal ")")
> +#define ASSERT_PTHREAD_INTERNAL_SIZE(type, internal) 			    \
> +  { _Static_assert (sizeof ((type) { { 0 } }).__size >= sizeof (internal),  \
> +		    "sizeof (" #type ".__size) < sizeof (" #internal ")");  \
> +    _Static_assert (_Alignof (type) >= _Alignof (internal),		    \
> +		    "_Aignof (" #type ") < _Alignof (" #internal ")"); }
>  
>  #define ASSERT_PTHREAD_STRING(x) __STRING (x)
>  #define ASSERT_PTHREAD_INTERNAL_OFFSET(type, member, offset)		\
>