AC_REQUIRE hell

[Akim Demaille]

Hi!

There must be something not going too well in the AC_REQUIRES of  
ltld.  In the attached configure.ac, some macros are issued out of  
order, which results in, for instance, shrext_cmds being used before  
its definition:

> $ grep -E 'shrext|If you need' configure
> eval libltdl_cv_shlibext=$shrext_cmds
> # If you need to create a library, use libtool.      <---- First  
> line in the macro
>       shrext_cmds=".dll"
> shrext_cmds=".so"
>   shrext_cmds=".dll"
>   shrext_cmds='`test .$module = .yes && echo .so || echo .dylib`'
>     shrext_cmds='.so'
>     shrext_cmds='.sl'
>     shrext_cmds='.sl'
>   shrext_cmds=".dll"
> shrext_cmds='`$ECHO "$shrext_cmds" | $SED  
> "$delay_single_quote_subst"`'
> shrext_cmds \
> shrext_cmds=$lt_shrext_cmds


I have a simple work around: instead of

AC_DEFUN([URBI_LTDL], [my macro])

I have

AC_DEFUN([URBI_LTDL], [m4_fatal([should never be used])])
m4_define([URBI_LTDL], [my macro])

The first line is to have aclocal notice that the macro is defined in  
an m4/ file, and the second is to avoid that URBI_LTDL define an  
AC_REQUIRE boundary.  I don't remember the details, but it seems  
suspicious to me that code using shrext_cmds is emitted before the  
contents of my macro.  Either somewhere there are m4_define that  
should be AC_DEFUN to define the AC_REQUIRE barriers (an error in  
Libtool), or when a macro OUTER invokes a macro INNER which requires  
REQUIRED then REQUIRED is output before OUTER, which seems wrong to me  
(an error in Autoconf).

Cheers!

configure.ac
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