Use the new castNode() macro in a number of places.

This is far from a pervasive conversion, but it's a good starting
point.

Author: Peter Eisentraut, with some minor changes by me
Reviewed-By: Tom Lane
Discussion: https://postgr.es/m/c5d387d9-3440-f5e0-f9d4-71d53b9fbe52@2ndquadrant.com

Author: anarazel

contrib/pg_stat_statements/pg_stat_statements.c

@@ -2382,9 +2382,8 @@ JumbleRangeTable(pgssJumbleState *jstate, List *rtable)
 
 	foreach(lc, rtable)
 	{
-		RangeTblEntry *rte = (RangeTblEntry *) lfirst(lc);
+		RangeTblEntry *rte = castNode(RangeTblEntry, lfirst(lc));
 
-		Assert(IsA(rte, RangeTblEntry));
 		APP_JUMB(rte->rtekind);
 		switch (rte->rtekind)
 		{
@@ -2570,7 +2569,7 @@ JumbleExpr(pgssJumbleState *jstate, Node *node)
 				APP_JUMB(sublink->subLinkType);
 				APP_JUMB(sublink->subLinkId);
 				JumbleExpr(jstate, (Node *) sublink->testexpr);
-				JumbleQuery(jstate, (Query *) sublink->subselect);
+				JumbleQuery(jstate, castNode(Query, sublink->subselect));
 			}
 			break;
 		case T_FieldSelect:
@@ -2636,9 +2635,8 @@ JumbleExpr(pgssJumbleState *jstate, Node *node)
 				JumbleExpr(jstate, (Node *) caseexpr->arg);
 				foreach(temp, caseexpr->args)
 				{
-					CaseWhen   *when = (CaseWhen *) lfirst(temp);
+					CaseWhen   *when = castNode(CaseWhen, lfirst(temp));
 
-					Assert(IsA(when, CaseWhen));
 					JumbleExpr(jstate, (Node *) when->expr);
 					JumbleExpr(jstate, (Node *) when->result);
 				}
@@ -2850,7 +2848,7 @@ JumbleExpr(pgssJumbleState *jstate, Node *node)
 
 				/* we store the string name because RTE_CTE RTEs need it */
 				APP_JUMB_STRING(cte->ctename);
-				JumbleQuery(jstate, (Query *) cte->ctequery);
+				JumbleQuery(jstate, castNode(Query, cte->ctequery));
 			}
 			break;
 		case T_SetOperationStmt:

contrib/postgres_fdw/deparse.c

@@ -1315,10 +1315,7 @@ deparseExplicitTargetList(List *tlist, List **retrieved_attrs,
 
 	foreach(lc, tlist)
 	{
-		TargetEntry *tle = (TargetEntry *) lfirst(lc);
-
-		/* Extract expression if TargetEntry node */
-		Assert(IsA(tle, TargetEntry));
+		TargetEntry *tle = castNode(TargetEntry, lfirst(lc));
 
 		if (i > 0)
 			appendStringInfoString(buf, ", ");

contrib/postgres_fdw/postgres_fdw.c

@@ -1159,9 +1159,7 @@ postgresGetForeignPlan(PlannerInfo *root,
 	 */
 	foreach(lc, scan_clauses)
 	{
-		RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
-
-		Assert(IsA(rinfo, RestrictInfo));
+		RestrictInfo *rinfo = castNode(RestrictInfo, lfirst(lc));
 
 		/* Ignore any pseudoconstants, they're dealt with elsewhere */
 		if (rinfo->pseudoconstant)
@@ -4958,14 +4956,12 @@ conversion_error_callback(void *arg)
 	{
 		/* error occurred in a scan against a foreign join */
 		ForeignScanState *fsstate = errpos->fsstate;
-		ForeignScan *fsplan = (ForeignScan *) fsstate->ss.ps.plan;
+		ForeignScan *fsplan = castNode(ForeignScan, fsstate->ss.ps.plan);
 		EState	   *estate = fsstate->ss.ps.state;
 		TargetEntry *tle;
 
-		Assert(IsA(fsplan, ForeignScan));
-		tle = (TargetEntry *) list_nth(fsplan->fdw_scan_tlist,
-									   errpos->cur_attno - 1);
-		Assert(IsA(tle, TargetEntry));
+		tle = castNode(TargetEntry, list_nth(fsplan->fdw_scan_tlist,
+											 errpos->cur_attno - 1));
 
 		/*
 		 * Target list can have Vars and expressions.  For Vars, we can get

src/backend/catalog/pg_proc.c

@@ -510,8 +510,7 @@ ProcedureCreate(const char *procedureName,
 											 Anum_pg_proc_proargdefaults,
 											 &isnull);
 			Assert(!isnull);
-			oldDefaults = (List *) stringToNode(TextDatumGetCString(proargdefaults));
-			Assert(IsA(oldDefaults, List));
+			oldDefaults = castNode(List, stringToNode(TextDatumGetCString(proargdefaults)));
 			Assert(list_length(oldDefaults) == oldproc->pronargdefaults);
 
 			/* new list can have more defaults than old, advance over 'em */

src/backend/commands/aggregatecmds.c

@@ -109,13 +109,13 @@ DefineAggregate(ParseState *pstate, List *name, List *args, bool oldstyle, List
 			aggKind = AGGKIND_ORDERED_SET;
 		else
 			numDirectArgs = 0;
-		args = (List *) linitial(args);
+		args = castNode(List, linitial(args));
 	}
 
 	/* Examine aggregate's definition clauses */
 	foreach(pl, parameters)
 	{
-		DefElem    *defel = (DefElem *) lfirst(pl);
+		DefElem    *defel = castNode(DefElem, lfirst(pl));
 
 		/*
 		 * sfunc1, stype1, and initcond1 are accepted as obsolete spellings

src/backend/commands/analyze.c

@@ -722,9 +722,9 @@ compute_index_stats(Relation onerel, double totalrows,
 		econtext->ecxt_scantuple = slot;
 
 		/* Set up execution state for predicate. */
-		predicate = (List *)
-			ExecPrepareExpr((Expr *) indexInfo->ii_Predicate,
-							estate);
+		predicate = castNode(List,
+							 ExecPrepareExpr((Expr *) indexInfo->ii_Predicate,
+											 estate));
 
 		/* Compute and save index expression values */
 		exprvals = (Datum *) palloc(numrows * attr_cnt * sizeof(Datum));

src/backend/commands/async.c

@@ -1636,7 +1636,7 @@ AtSubCommit_Notify(void)
 	List	   *parentPendingActions;
 	List	   *parentPendingNotifies;
 
-	parentPendingActions = (List *) linitial(upperPendingActions);
+	parentPendingActions = castNode(List, linitial(upperPendingActions));
 	upperPendingActions = list_delete_first(upperPendingActions);
 
 	Assert(list_length(upperPendingActions) ==
@@ -1647,7 +1647,7 @@ AtSubCommit_Notify(void)
 	 */
 	pendingActions = list_concat(parentPendingActions, pendingActions);
 
-	parentPendingNotifies = (List *) linitial(upperPendingNotifies);
+	parentPendingNotifies = castNode(List, linitial(upperPendingNotifies));
 	upperPendingNotifies = list_delete_first(upperPendingNotifies);
 
 	Assert(list_length(upperPendingNotifies) ==
@@ -1679,13 +1679,13 @@ AtSubAbort_Notify(void)
 	 */
 	while (list_length(upperPendingActions) > my_level - 2)
 	{
-		pendingActions = (List *) linitial(upperPendingActions);
+		pendingActions = castNode(List, linitial(upperPendingActions));
 		upperPendingActions = list_delete_first(upperPendingActions);
 	}
 
 	while (list_length(upperPendingNotifies) > my_level - 2)
 	{
-		pendingNotifies = (List *) linitial(upperPendingNotifies);
+		pendingNotifies = castNode(List, linitial(upperPendingNotifies));
 		upperPendingNotifies = list_delete_first(upperPendingNotifies);
 	}
 }

src/backend/commands/collationcmds.c

@@ -61,7 +61,7 @@ DefineCollation(ParseState *pstate, List *names, List *parameters)
 
 	foreach(pl, parameters)
 	{
-		DefElem    *defel = (DefElem *) lfirst(pl);
+		DefElem    *defel = castNode(DefElem, lfirst(pl));
 		DefElem   **defelp;
 
 		if (pg_strcasecmp(defel->defname, "from") == 0)

src/backend/commands/constraint.c

@@ -37,7 +37,7 @@
 Datum
 unique_key_recheck(PG_FUNCTION_ARGS)
 {
-	TriggerData *trigdata = (TriggerData *) fcinfo->context;
+	TriggerData *trigdata = castNode(TriggerData, fcinfo->context);
 	const char *funcname = "unique_key_recheck";
 	HeapTuple	new_row;
 	ItemPointerData tmptid;

src/backend/commands/copy.c

@@ -1026,7 +1026,7 @@ ProcessCopyOptions(ParseState *pstate,
 	/* Extract options from the statement node tree */
 	foreach(option, options)
 	{
-		DefElem    *defel = (DefElem *) lfirst(option);
+		DefElem    *defel = castNode(DefElem, lfirst(option));
 
 		if (strcmp(defel->defname, "format") == 0)
 		{
@@ -1139,7 +1139,7 @@ ProcessCopyOptions(ParseState *pstate,
 						 errmsg("conflicting or redundant options"),
 						 parser_errposition(pstate, defel->location)));
 			if (defel->arg && IsA(defel->arg, List))
-				cstate->force_notnull = (List *) defel->arg;
+				cstate->force_notnull = castNode(List, defel->arg);
 			else
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
@@ -1154,7 +1154,7 @@ ProcessCopyOptions(ParseState *pstate,
 						(errcode(ERRCODE_SYNTAX_ERROR),
 						 errmsg("conflicting or redundant options")));
 			if (defel->arg && IsA(defel->arg, List))
-				cstate->force_null = (List *) defel->arg;
+				cstate->force_null = castNode(List, defel->arg);
 			else
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
@@ -1176,7 +1176,7 @@ ProcessCopyOptions(ParseState *pstate,
 						 parser_errposition(pstate, defel->location)));
 			cstate->convert_selectively = true;
 			if (defel->arg == NULL || IsA(defel->arg, List))
-				cstate->convert_select = (List *) defel->arg;
+				cstate->convert_select = castNode(List, defel->arg);
 			else
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
@@ -1479,7 +1479,7 @@ BeginCopy(ParseState *pstate,
 			/* examine queries to determine which error message to issue */
 			foreach(lc, rewritten)
 			{
-				Query	   *q = (Query *) lfirst(lc);
+				Query	   *q = castNode(Query, lfirst(lc));
 
 				if (q->querySource == QSRC_QUAL_INSTEAD_RULE)
 					ereport(ERROR,
@@ -1496,7 +1496,7 @@ BeginCopy(ParseState *pstate,
 					 errmsg("multi-statement DO INSTEAD rules are not supported for COPY")));
 		}
 
-		query = (Query *) linitial(rewritten);
+		query = castNode(Query, linitial(rewritten));
 
 		/* The grammar allows SELECT INTO, but we don't support that */
 		if (query->utilityStmt != NULL &&