Re: AC_CHECK_ALIGNOF maximum ??

[Bob Friesenhahn]

On Thu, 20 Jun 2013, 'Chris Hall' wrote:

> I hope I am in the right place, if not please direct me !
>
> I have found:
>
>  AC_CHECK_ALIGNOF (type, [includes = ?AC_INCLUDES_DEFAULT?])
>
> which is quite lovely, as far as it goes... but it does not appear to
> tell me the maximum possible alignment.
>
> Of course gcc gives __BIGGEST_ALIGNMENT__ for this.  And I guess other
> compilers do something similar...
>
> ...but I cannot help feeling that autoconf should cover this, but if
> it does, I have failed to find where :-(

How would Autoconf portably test for this and for what purpose would 
you use this information for?

Compile-time estimation of biggest alignment seems risky to me if it 
is used for any serious purpose.  If all of the software in the 
running application was not compiled with the same flags, then the 
compiled-in value may be wrong.

Bob
--
Bob Friesenhahn
address@hidden, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/