Improve node type forward reference

From df3f09a1d12c91595ad0702a17a2a7d884f5193f Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Mon, 14 Oct 2024 08:52:34 +0200
Subject: [PATCH 1/2] Improve node type forward reference

Instead of using Node *, we can use an incomplete struct.  That way,
everything has the correct type and fewer casts are required.  This
technique is already used elsewhere in node type definitions.
---
 src/backend/commands/createas.c | 2 +-
 src/backend/parser/analyze.c    | 2 +-
 src/include/nodes/primnodes.h   | 5 ++---
 3 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/src/backend/commands/createas.c b/src/backend/commands/createas.c
index 0b629b1f79c..68ec122dbf9 100644
--- a/src/backend/commands/createas.c
+++ b/src/backend/commands/createas.c
@@ -133,7 +133,7 @@ create_ctas_internal(List *attrList, IntoClause *into)
 	if (is_matview)
 	{
 		/* StoreViewQuery scribbles on tree, so make a copy */
-		Query	   *query = (Query *) copyObject(into->viewQuery);
+		Query	   *query = copyObject(into->viewQuery);
 
 		StoreViewQuery(intoRelationAddr.objectId, query, false);
 		CommandCounterIncrement();
diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c
index e901203424d..5e5e0b1c5cf 100644
--- a/src/backend/parser/analyze.c
+++ b/src/backend/parser/analyze.c
@@ -3076,7 +3076,7 @@ transformCreateTableAsStmt(ParseState *pstate, CreateTableAsStmt *stmt)
 		 * in the IntoClause because that's where intorel_startup() can
 		 * conveniently get it from.
 		 */
-		stmt->into->viewQuery = (Node *) copyObject(query);
+		stmt->into->viewQuery = copyObject(query);
 	}
 
 	/* represent the command as a utility Query */
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index ea47652adb8..f2677b2da1d 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -152,8 +152,7 @@ typedef struct TableFunc
  * For CREATE MATERIALIZED VIEW, viewQuery is the parsed-but-not-rewritten
  * SELECT Query for the view; otherwise it's NULL.  This is irrelevant in
  * the query jumbling as CreateTableAsStmt already includes a reference to
- * its own Query, so ignore it.  (Although it's actually Query*, we declare
- * it as Node* to avoid a forward reference.)
+ * its own Query, so ignore it.
  */
 typedef struct IntoClause
 {
@@ -166,7 +165,7 @@ typedef struct IntoClause
 	OnCommitAction onCommit;	/* what do we do at COMMIT? */
 	char	   *tableSpaceName; /* table space to use, or NULL */
 	/* materialized view's SELECT query */
-	Node	   *viewQuery pg_node_attr(query_jumble_ignore);
+	struct Query *viewQuery pg_node_attr(query_jumble_ignore);
 	bool		skipData;		/* true for WITH NO DATA */
 } IntoClause;
 
-- 
2.47.0

From 2cc8cde745140a17c35c17fe3ff10f0a4d5cd12a Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Mon, 14 Oct 2024 09:00:15 +0200
Subject: [PATCH 2/2] Fix unnecessary casts of copyObject() result

The result is already of the correct type, so these casts don't do
anything.
---
 src/backend/commands/trigger.c     | 2 +-
 src/backend/nodes/nodeFuncs.c      | 4 ++--
 src/backend/rewrite/rewriteManip.c | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/backend/commands/trigger.c b/src/backend/commands/trigger.c
index 3671e82535e..09356e46d16 100644
--- a/src/backend/commands/trigger.c
+++ b/src/backend/commands/trigger.c
@@ -1169,7 +1169,7 @@ CreateTriggerFiringOn(CreateTrigStmt *stmt, const char *queryString,
 			 * Initialize our fabricated parse node by copying the original
 			 * one, then resetting fields that we pass separately.
 			 */
-			childStmt = (CreateTrigStmt *) copyObject(stmt);
+			childStmt = copyObject(stmt);
 			childStmt->funcname = NIL;
 			childStmt->whenClause = NULL;
 
diff --git a/src/backend/nodes/nodeFuncs.c b/src/backend/nodes/nodeFuncs.c
index 0d00e029f32..f76072228c9 100644
--- a/src/backend/nodes/nodeFuncs.c
+++ b/src/backend/nodes/nodeFuncs.c
@@ -2996,7 +2996,7 @@ expression_tree_mutator_impl(Node *node,
 		case T_SortGroupClause:
 		case T_CTESearchClause:
 		case T_MergeSupportFunc:
-			return (Node *) copyObject(node);
+			return copyObject(node);
 		case T_WithCheckOption:
 			{
 				WithCheckOption *wco = (WithCheckOption *) node;
@@ -3604,7 +3604,7 @@ expression_tree_mutator_impl(Node *node,
 			break;
 		case T_PartitionPruneStepCombine:
 			/* no expression sub-nodes */
-			return (Node *) copyObject(node);
+			return copyObject(node);
 		case T_JoinExpr:
 			{
 				JoinExpr   *join = (JoinExpr *) node;
diff --git a/src/backend/rewrite/rewriteManip.c b/src/backend/rewrite/rewriteManip.c
index b20625fbd2b..8f90afb3269 100644
--- a/src/backend/rewrite/rewriteManip.c
+++ b/src/backend/rewrite/rewriteManip.c
@@ -1715,7 +1715,7 @@ ReplaceVarsFromTargetList_callback(Var *var,
 				break;
 
 			case REPLACEVARS_CHANGE_VARNO:
-				var = (Var *) copyObject(var);
+				var = copyObject(var);
 				var->varno = rcon->nomatch_varno;
 				/* we leave the syntactic referent alone */
 				return (Node *) var;
-- 
2.47.0