[Bug c/53037] warn_if_not_aligned(X)

["hpa at zytor dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53037

--- Comment #30 from H. Peter Anvin <hpa at zytor dot com> ---
On August 18, 2017 3:52:12 PM CDT, "hjl.tools at gmail dot com"
<gcc-bugzilla@gcc.gnu.org> wrote:
>https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53037
>
>--- Comment #29 from H.J. Lu <hjl.tools at gmail dot com> ---
>(In reply to ro@CeBiTec.Uni-Bielefeld.DE from comment #28)
>> > --- Comment #27 from H.J. Lu <hjl.tools at gmail dot com> ---
>> 
>> > What are error messages?
>> 
>> None, the warnings are simply missing.
>> 
>> 	Rainer
>
>Sparc defines STRICT_ALIGNMENT which leads to
>
>      unsigned mode_align = GET_MODE_ALIGNMENT (TYPE_MODE (type));
>
>    /* Don't override a larger alignment requirement coming from a user
>         alignment of one of the fields.  */
>      if (mode_align >= TYPE_ALIGN (type))
>        {
>          SET_TYPE_ALIGN (type, mode_align);
>          TYPE_USER_ALIGN (type) = 0; 
>        }
>
>so __attribute__ ((packed)) is basically ignored on Sparc.  This patch
>
>diff --git a/gcc/stor-layout.c b/gcc/stor-layout.c
>index 3028d55773a..6dd605810ac 100644
>--- a/gcc/stor-layout.c
>+++ b/gcc/stor-layout.c
>@@ -1784,7 +1784,7 @@ finalize_type_size (tree type)
>
>    /* Don't override a larger alignment requirement coming from a user
>    alignment of one of the fields.  */
>-      if (mode_align >= TYPE_ALIGN (type))
>+      if (mode_align > TYPE_ALIGN (type))
>   {
>     SET_TYPE_ALIGN (type, mode_align);
>     TYPE_USER_ALIGN (type) = 0;
>
>works with cross compiler.  But I have no idea if it is correct.

Ignoring __attribute__((packed)) I would consider to be a super serious error.