Grammar object type refactoring

Unify the grammar of COMMENT, DROP, and SECURITY LABEL further.  They
all effectively just take an object address for later processing, so
we can make the grammar more generalized.  Some extra checking about
which object types are supported can be done later in the statement
execution.

Discussion: https://www.postgresql.org/message-id/flat/163c00a5-f634-ca52-fc7c-0e53deda8735%402ndquadrant.com

src/backend/commands/seclabel.c

@@ -33,6 +33,75 @@ typedef struct
 
 static List *label_provider_list = NIL;
 
+static bool
+SecLabelSupportsObjectType(ObjectType objtype)
+{
+	switch (objtype)
+	{
+		case OBJECT_AGGREGATE:
+		case OBJECT_COLUMN:
+		case OBJECT_DATABASE:
+		case OBJECT_DOMAIN:
+		case OBJECT_EVENT_TRIGGER:
+		case OBJECT_FOREIGN_TABLE:
+		case OBJECT_FUNCTION:
+		case OBJECT_LANGUAGE:
+		case OBJECT_LARGEOBJECT:
+		case OBJECT_MATVIEW:
+		case OBJECT_PROCEDURE:
+		case OBJECT_PUBLICATION:
+		case OBJECT_ROLE:
+		case OBJECT_ROUTINE:
+		case OBJECT_SCHEMA:
+		case OBJECT_SEQUENCE:
+		case OBJECT_SUBSCRIPTION:
+		case OBJECT_TABLE:
+		case OBJECT_TABLESPACE:
+		case OBJECT_TYPE:
+		case OBJECT_VIEW:
+			return true;
+
+		case OBJECT_ACCESS_METHOD:
+		case OBJECT_AMOP:
+		case OBJECT_AMPROC:
+		case OBJECT_ATTRIBUTE:
+		case OBJECT_CAST:
+		case OBJECT_COLLATION:
+		case OBJECT_CONVERSION:
+		case OBJECT_DEFAULT:
+		case OBJECT_DEFACL:
+		case OBJECT_DOMCONSTRAINT:
+		case OBJECT_EXTENSION:
+		case OBJECT_FDW:
+		case OBJECT_FOREIGN_SERVER:
+		case OBJECT_INDEX:
+		case OBJECT_OPCLASS:
+		case OBJECT_OPERATOR:
+		case OBJECT_OPFAMILY:
+		case OBJECT_POLICY:
+		case OBJECT_PUBLICATION_REL:
+		case OBJECT_RULE:
+		case OBJECT_STATISTIC_EXT:
+		case OBJECT_TABCONSTRAINT:
+		case OBJECT_TRANSFORM:
+		case OBJECT_TRIGGER:
+		case OBJECT_TSCONFIGURATION:
+		case OBJECT_TSDICTIONARY:
+		case OBJECT_TSPARSER:
+		case OBJECT_TSTEMPLATE:
+		case OBJECT_USER_MAPPING:
+			return false;
+
+			/*
+			 * There's intentionally no default: case here; we want the
+			 * compiler to warn if a new ObjectType hasn't been handled above.
+			 */
+	}
+
+	/* Shouldn't get here, but if we do, say "no support" */
+	return false;
+}
+
 /*
  * ExecSecLabelStmt --
  *
@@ -83,6 +152,11 @@ ExecSecLabelStmt(SecLabelStmt *stmt)
 							stmt->provider)));
 	}
 
+	if (!SecLabelSupportsObjectType(stmt->objtype))
+		ereport(ERROR,
+				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				 errmsg("security labels are not supported for this type of object")));
+
 	/*
 	 * Translate the parser representation which identifies this object into
 	 * an ObjectAddress. get_object_address() will throw an error if the