Re: 40-better-messages.patch

[Akim Demaille]

   @@ -5617,40 +5634,36 @@ sub variable_define ($$$$$$)
    
      $cond ||= 'TRUE';
    
   -  check_ambiguous_conditional ($var, $cond)
   -    unless $type eq '+';
   -
   -  if (! defined $conditional{$var}{$cond})
   +  # A variable which was `+=' must not be `='.
   +  if (defined $var_was_plus_eq{$var})
   +    {
   +      if ($var_was_plus_eq{$var} && $type ne '+')
   +    {
   +      am_line_error ($var,
   +                     ("$var was set with `+=' "
   +                      . "and is now set with `$type='"));
   +    }
   +    }
   +  else
        {
   -      # Initialize: we rely on defined.
   -      $conditional{$var}{$cond} = '';
   -
   -      # The first assignment to a macro sets the line number.  Ideally
   -      # I suppose we would associate line numbers with random bits of
   -      # text.
   -      # FIXME: We sometimes redefine some variables, but we want to keep
   -      # the original location.  More subs are needed to handle properly
   -      # variables.  Once this done, remove this hack.
   -      $content_lines{$var} = $where
   -    unless defined $content_lines{$var};
   -
   -      # If first assignment, set `+=' indicator.
          $var_was_plus_eq{$var} = $type eq '+' && ! $var_is_am{$var};
        }
    
   +  # An Automake variable can be given to the user, but not the converse.
      if (! defined $var_is_am{$var} || !$var_is_am)
        {
          $var_is_am{$var} = $var_is_am;
        }
    
   -  if ($type eq '+')
   +  # Differentiate the first assignment (including with `+=').
   +  if ($type eq '+' && defined $conditional{$var}{$cond})
        {
          if (substr ($conditional{$var}{$cond}, -1) eq "\n")
   -       {
   -         # Insert a backslash before a trailing newline.
   -         $conditional{$var}{$cond} =
   -       substr ($conditional{$var}{$cond}, 0, -1) . "\\\n";
   -       }
   +    {
   +      # Insert a backslash before a trailing newline.
   +      $conditional{$var}{$cond} =
   +        substr ($conditional{$var}{$cond}, 0, -1) . "\\\n";
   +    }
          elsif ($conditional{$var}{$cond})
           {
             # Insert a separator.
   

It took me a very long while to formalize the permissions over
variables in Automake.  Rules are emerging slowly each time I convert
a new sub (which was directly poking into %conditional) to use
macro_define.


     @@ -6567,7 +6590,16 @@ sub read_main_am_file
      
          # First pass.
          &define_standard_variables;
     -    my %saved_conditional = %conditional;
     +    # Deep copy. With `%saved_conditional = %conditional' modifying
     +    # one modifes the other.
     +    my %saved_conditional;
     +    foreach my $var (keys %conditional)
     +      {
     +  foreach my $cond (keys %{$conditional{$var}})
     +    {
     +      $saved_conditional{$var}{$cond} = $conditional{$var}{$cond};
     +    }
     +      }
      
          # Read user file, but discard text of variable assignments we just
          # made.


Later I have found a more satisfying means (IMHO) to handle the
special case due to these variables.  A way to understand my claim is
`just say yes, since this code is obsoleted later with something more
intelligent addressing this issue'.

But before doing this, I need more technology, brought in the next patches.