Fix cases of discarding result from list API functions

petere · petere · commit c77f6f50e418 · 2020-11-11T08:03:51.000+01:00
Two cases violated list APIs by throwing away the return value. While the code was technically correct, it relied on internal knowledge of the list implementation, and the code wasn't really gaining anything that way. It is planned to make this a compiler warning in the future, so just fix these cases by assigning the return value properly. Reviewed-by: Michael Paquier <michael@paquier.xyz> Discussion: https://www.postgresql.org/message-id/flat/e3753562-99cd-b65f-5aca-687dfd1ec2fc@2ndquadrant.com
diff --git a/src/backend/commands/lockcmds.c b/src/backend/commands/lockcmds.c
@@ -266,7 +266,7 @@ LockViewRecurse(Oid reloid, LOCKMODE lockmode, bool nowait,
 
 	LockViewRecurse_walker((Node *) viewquery, &context);
 
-	(void) list_delete_last(context.ancestor_views);
+	context.ancestor_views = list_delete_last(context.ancestor_views);
 
 	table_close(view, NoLock);
 }
diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c
@@ -1475,8 +1475,7 @@ transformValuesClause(ParseState *pstate, SelectStmt *stmt)
 			Node	   *col = (Node *) lfirst(lc);
 			List	   *sublist = lfirst(lc2);
 
-			/* sublist pointer in exprsLists won't need adjustment */
-			(void) lappend(sublist, col);
+			sublist = lappend(sublist, col);
 		}
 		list_free(colexprs[i]);
 	}

Original file line number	Diff line number	Diff line change
`@@ -266,7 +266,7 @@ LockViewRecurse(Oid reloid, LOCKMODE lockmode, bool nowait,`
`266`	`266`
`267`	`267`	`LockViewRecurse_walker((Node *) viewquery, &context);`
`268`	`268`
`269`		`- (void) list_delete_last(context.ancestor_views);`
	`269`	`+ context.ancestor_views = list_delete_last(context.ancestor_views);`
`270`	`270`
`271`	`271`	`table_close(view, NoLock);`
`272`	`272`	`}`
Original file line number	Diff line number	Diff line change
`@@ -1475,8 +1475,7 @@ transformValuesClause(ParseState pstate, SelectStmt stmt)`
`1475`	`1475`	`Node col = (Node ) lfirst(lc);`
`1476`	`1476`	`List *sublist = lfirst(lc2);`
`1477`	`1477`
`1478`		`- /* sublist pointer in exprsLists won't need adjustment */`
`1479`		`- (void) lappend(sublist, col);`
	`1478`	`+ sublist = lappend(sublist, col);`
`1480`	`1479`	`}`
`1481`	`1480`	`list_free(colexprs[i]);`
`1482`	`1481`	`}`