[Automake-NG] [PATCH 1/3] var: add VAR_COMPUTED source

[Paolo Bonzini]

We want AUTOMAKE_OPTIONS in Makefile.in to be the combination of
configure.ac and Makefile.am options.  Define a new variable owner
for this, because we need to override the Makefile.am value
unconditionally and never emit warnings.

* lib/Automake/VarDef.pm (VAR_COMPUTED): New.
(dump): Print it.
* lib/Automake/Variable.pm (define): Check that VAR_COMPUTED variables
were not conditionally defined, and always allow them to override
previous definitions.
---
 lib/Automake/VarDef.pm   | 18 ++++++++++++------
 lib/Automake/Variable.pm | 12 +++++++++++-
 2 file modificati, 23 inserzioni(+), 7 rimozioni(-)

diff --git a/lib/Automake/VarDef.pm b/lib/Automake/VarDef.pm
index 6bb9fa6..7d2a321 100644
--- a/lib/Automake/VarDef.pm
+++ b/lib/Automake/VarDef.pm
@@ -24,7 +24,7 @@ use Automake::ItemDef;
 require Exporter;
 use vars '@ISA', '@EXPORT';
 @ISA = qw/Automake::ItemDef Exporter/;
address@hidden = qw (&VAR_AUTOMAKE &VAR_CONFIGURE &VAR_MAKEFILE);
address@hidden = qw (&VAR_AUTOMAKE &VAR_CONFIGURE &VAR_MAKEFILE &VAR_COMPUTED);
 
 =head1 NAME
 
@@ -75,11 +75,12 @@ This class gathers data related to one Makefile-variable 
definition.
 
 =over 4
 
-=item C<VAR_AUTOMAKE>, C<VAR_CONFIGURE>, C<VAR_MAKEFILE>
+=item C<VAR_AUTOMAKE>, C<VAR_CONFIGURE>, C<VAR_MAKEFILE>, C<VAR_COMPUTED>
 
 Possible owners for variables.  A variable can be defined
-by Automake, in F<configure.ac> (using C<AC_SUBST>), or in
-the user's F<Makefile.am>.
+by Automake (this is also the case for C<VAR_COMPUTED>, which
+has highest priority), in F<configure.ac> (using C<AC_SUBST>),
+or in the user's F<Makefile.am>.
 
 =cut
 
@@ -88,6 +89,7 @@ the user's F<Makefile.am>.
 use constant VAR_AUTOMAKE => 0; # Variable defined by Automake.
 use constant VAR_CONFIGURE => 1;# Variable defined in configure.ac.
 use constant VAR_MAKEFILE => 2; # Variable defined in Makefile.am.
+use constant VAR_COMPUTED => 3; # Variable computed by Automake.
 
 =back
 
@@ -114,8 +116,8 @@ C<$type> should be C<''> for definitions made with C<=>, 
and C<':'>
 for those made with C<:=>.
 
 C<$owner> specifies who owns the variables, it can be one of
-C<VAR_AUTOMAKE>, C<VAR_CONFIGURE>, or C<VAR_MAKEFILE> (see these
-definitions).
+C<VAR_AUTOMAKE>, C<VAR_CONFIGURE>, C<VAR_MAKEFILE>, or
+C<VAR_COMPUTED> (see these definitions).
 
 =cut
 
@@ -279,6 +281,10 @@ sub dump ($)
     {
       $owner = 'Makefile';
     }
+  elsif ($owner == VAR_COMPUTED)
+    {
+      $owner = 'Automake (computed variable)';
+    }
   else
     {
       prog_error ("unexpected owner");
diff --git a/lib/Automake/Variable.pm b/lib/Automake/Variable.pm
index 50a4dad..dbda0a0 100644
--- a/lib/Automake/Variable.pm
+++ b/lib/Automake/Variable.pm
@@ -782,6 +782,13 @@ sub define ($$$$$$$)
        }
     }
 
+  # Additional checks for computed variables
+  if ($owner == VAR_COMPUTED && ! $new_var)
+    {
+      # A computed variable must be unconditional.
+      $self->check_defined_unconditionally;
+    }
+
   # Differentiate assignment types.
 
   # 1. append (+=) to a variable defined for current condition
@@ -849,10 +856,13 @@ sub define ($$$$$$$)
       # There must be no previous value unless the user is redefining
       # an Automake variable or an AC_SUBST variable for an existing
       # condition.
+      # Computed variables (currently only AUTOMAKE_OPTIONS) can always
+      # override user definitions.
       _check_ambiguous_condition ($self, $cond, $where)
        unless (!$new_var
                && (($def->owner == VAR_AUTOMAKE && $owner != VAR_AUTOMAKE)
-                   || $def->owner == VAR_CONFIGURE));
+                   || $def->owner == VAR_CONFIGURE
+                   || $owner == VAR_COMPUTED));
 
       # Never decrease an owner.
       $owner = $def->owner
-- 
1.7.11.2