Disambiguate tag names in RCG

Because top level subsystems are never flattened, their goto tags are never pre-fixed with the subsystem name. If the same tag is used at the top level, then there it's ambiguous to the parser which goto block to choose.

This change prefixes top level subsystem names on to all child Goto and From tag names.

src/epics/util/lib/Parser3.pm

@@ -1542,6 +1542,26 @@ if (0) {
    }
 }
 
+#// \b sub \b prefix_tag_names \n
+#// Prefix the system name on all child From and Goto tag names
+#// Use only on top level subsystems because they are not flattened
+#// necessary to differentiate top level tags from other tags.
+sub prefix_tag_names {
+   my ($node, $sysname) = @_;
+
+   foreach (@{$node->{NEXT}}) {
+      my $btype = ${$_->{FIELDS}}{BlockType};
+      if(($btype eq "From") || ($btype eq "Goto")) {
+         print("prefixing tag ${$_->{FIELDS}}{GotoTag} to ");
+	 ${$_->{FIELDS}}{GotoTag} = $sysname . "_" . ${$_->{FIELDS}}{GotoTag};
+	 print("${$_->{FIELDS}}{GotoTag}\n");
+      }
+      prefix_tag_names($_, $sysname);
+   }
+
+
+}
+
 #// \b sub \b flatten_nested_subsystems \n
 sub flatten_nested_subsystems {
    my ($node) =  @_;
@@ -1584,6 +1604,7 @@ if (1) {
             flatten($ssub);
 	  }
 	}
+	prefix_tag_names($_, ${$_->{FIELDS}}{Name});
      }
    }
    #print ::EPICS "test_points ONE_PPS $::extraTestPoints\n";