Re: AM_SUBST_IGNORE = AC_SUBST without Makefile variable definition

[Ralf Wildenhues]

Hi Alexandre,

* Alexandre Duret-Lutz wrote on Mon, Oct 17, 2005 at 10:44:27PM CEST:
> Occasionally we want to disable automatic variable definitions
> of AC_SUBSTitutions.  Two cases were already hardcoded into
> automake (AMDEPBACKSLASH and ANSI2KNR). I had been considering
> adding such a feature since Autoconf introduced multiline
> AC_SUBSTitutions.  Now I think Ralf's suggestion in PR/477 makes
> it even more relevant.

Thanks for tackling this!  Two comments:

I don't know whether AM_SUBST_IGNORE is a great name, but then again, I
can't think of a better one either; AM_SUBST_NOVAR or _NOSET aren't.

Also, see typo below.

Cheers,
Ralf

> 2005-10-17  Alexandre Duret-Lutz  <address@hidden>
> 
>       * automake.in (%ignored_configure_vars): New variable.
>       (scan_autoconf_traces): Scan for AM_SUBST_IGNORE_TRACE and fill
>       %ignored_configure_vars.
>       (define_configure_variable): Declare ignored configure variables
>       as VAR_SILENT.  Do not special-case AMDEPBACKSLASH and ANSI2KNR
>       w.r.t. VAR_SILENT.
>       * doc/automake.texi (Optional): Document AM_SUBST_IGNORE.
>       * m4/substign.m4: New file.
>       * m4/Makefile.am (dist_m4data_DATA): Add substign.m4.
>       * m4/cond.m4: AM_SUBST_IGNORE $1_TRUE and $1_FALSE (PR automake/477).
>       * m4/depend.m4: AM_SUBST_IGNORE AMDEPBACKSLASH.
>       * m4/protos.m4: AM_SUBST_IGNORE ANSI2KNR.
>       * tests/cond.test: Make sure TEST_FALSE and TEST_TRUE are not defined.

*snip*
> Index: doc/automake.texi
> ===================================================================
> RCS file: /cvs/automake/automake/doc/automake.texi,v
> retrieving revision 1.122
> diff -u -r1.122 automake.texi
> --- doc/automake.texi 13 Sep 2005 23:14:55 -0000      1.122
> +++ doc/automake.texi 17 Oct 2005 20:35:45 -0000
> @@ -1588,6 +1588,9 @@
>  you can use these variables in any @file{Makefile.am} if
>  @code{AC_PATH_XTRA} is called.
>  
> address@hidden (see below) can be used to declare
> +substitutions that should not be defined as @file{Makefile} variables.
> +
>  @item AM_C_PROTOTYPES
>  This is required when using automatic de-ANSI-fication; see @ref{ANSI}.
>  
> @@ -1606,6 +1609,16 @@
>  @code{MAINTAINER_MODE} conditional, which you can use in your own
>  @file{Makefile.am}.  @xref{maintainer-mode}.
>  
> address@hidden AM_SUBST_IGNORE
> +This is similar to and uses the same syntax as @code{AC_SUBST} (see
> +above), except @command{automake} will not output a definition of the
> +variable in any @file{Makefile.in} it produces.
> +
> +It is occasionally necessary to let Automake ignore some substitutions
> +that are not meant to be used as @file{Makefile} variables.  For
> +instance values that are terminated by a backslash would cause syntax
> +error is they were defined as @file{Makefile} variables.

s/is/if/

> +
>  @item m4_include
>  Files included by @file{configure.ac} using this macro will be
>  detected by Automake and automatically distributed.  They will also
*snip*