On Fri, Sep 27, 2002 at 08:58:18AM +0200, Akim Demaille wrote:
>
> | # PGAC_CHECK_ALIGNOF(TYPE, [INCLUDES = DEFAULT-INCLUDES])
> | # -----------------------------------------------------
> | # Find the alignment requirement of the given type. Define the result
> | # as ALIGNOF_TYPE. This macro works even when cross compiling.
> | # (Modelled after AC_CHECK_SIZEOF.)
> |
> | AC_DEFUN([PGAC_CHECK_ALIGNOF],
> | [AS_LITERAL_IF([$1], [],
> | [AC_FATAL([$0: requires literal arguments])])dnl
> | AC_CHECK_TYPE([$1], [], [], [$2])
> | AC_CACHE_CHECK([alignment of $1], [AS_TR_SH([pgac_cv_alignof_$1])],
> | [if test "$AS_TR_SH([ac_cv_type_$1])" = yes; then
> | _AC_COMPUTE_INT([((char*) & pgac_struct.field) - ((char*) & pgac_struct)],
> | [AS_TR_SH([pgac_cv_alignof_$1])],
> | [AC_INCLUDES_DEFAULT([$2])
> | struct { char filler; $1 field; } pgac_struct;],
> | [AC_MSG_ERROR([cannot compute alignment of $1, 77])])
> | else
> | AS_TR_SH([pgac_cv_alignof_$1])=0
> | fi])dnl
> | AC_DEFINE_UNQUOTED(AS_TR_CPP(alignof_$1),
> | [$AS_TR_SH([pgac_cv_alignof_$1])],
> | [The alignment requirement of a `$1'])
> | ])# PGAC_CHECK_ALIGNOF
>
> This guy seems swallowable... It's impressively already in 2.5x style :)
There is form, but no content. This can be done using AC_TRY_RUN (or other
runtime check), is otherwise no better than a random guess. Alignment problems
don't show up in compiling, but at runtime.
--
Thomas E. Dickey <[EMAIL PROTECTED]>
http://invisible-island.net
ftp://invisible-island.net
