gen_node_support.pl: Mark location fields as type alias ParseLoc

Instead of the rather ugly type=int + name ~= location$, we now have a
marker type for offset pointers or sizes that are only relevant when a
query text is included, which decreases the complexity required in
gen_node_support.pl for handling these values.

Author: Matthias van de Meent <boekewurm+postgres@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/CAEze2WgrCiR3JZmWyB0YTc8HV7ewRdx13j0CqD6mVkYAW+SFGQ@mail.gmail.com

Author: petere

src/backend/nodes/gen_node_support.pl

@@ -777,7 +777,7 @@ sub elem
 			print $eff "\tCOMPARE_BITMAPSET_FIELD($f);\n"
 			  unless $equal_ignore;
 		}
-		elsif ($t eq 'int' && $f =~ 'location$')
+		elsif ($t eq 'ParseLoc')
 		{
 			print $cff "\tCOPY_LOCATION_FIELD($f);\n" unless $copy_ignore;
 			print $eff "\tCOMPARE_LOCATION_FIELD($f);\n" unless $equal_ignore;
@@ -1010,7 +1010,7 @@ sub elem
 			print $off "\tWRITE_BOOL_FIELD($f);\n";
 			print $rff "\tREAD_BOOL_FIELD($f);\n" unless $no_read;
 		}
-		elsif ($t eq 'int' && $f =~ 'location$')
+		elsif ($t eq 'ParseLoc')
 		{
 			print $off "\tWRITE_LOCATION_FIELD($f);\n";
 			print $rff "\tREAD_LOCATION_FIELD($f);\n" unless $no_read;
@@ -1303,7 +1303,7 @@ sub elem
 			print $jff "\tJUMBLE_NODE($f);\n"
 			  unless $query_jumble_ignore;
 		}
-		elsif ($t eq 'int' && $f =~ 'location$')
+		elsif ($t eq 'ParseLoc')
 		{
 			# Track the node's location only if directly requested.
 			if ($query_jumble_location)

src/include/nodes/nodes.h

@@ -229,6 +229,15 @@ extern void *copyObjectImpl(const void *from);
 extern bool equal(const void *a, const void *b);
 
 
+/*
+ * Typedef for parse location.  This is just an int, but this way
+ * gen_node_support.pl knows which fields should get special treatment for
+ * location values.
+ *
+ * -1 is used for unknown.
+ */
+typedef int ParseLoc;
+
 /*
  * Typedefs for identifying qualifier selectivities, plan costs, and row
  * counts as such.  These are just plain "double"s, but declaring a variable