Cast result of copyObject() to correct type

copyObject() is declared to return void *, which allows easily assigning
the result independent of the input, but it loses all type checking.

If the compiler supports typeof or something similar, cast the result to
the input type.  This creates a greater amount of type safety.  In some
cases, where the result is assigned to a generic type such as Node * or
Expr *, new casts are now necessary, but in general casts are now
unnecessary in the normal case and indicate that something unusual is
happening.

Reviewed-by: Mark Dilger <hornschnorter@gmail.com>

config/c-compiler.m4

@@ -178,6 +178,33 @@ fi])# PGAC_C_STATIC_ASSERT
 
 
 
+# PGAC_C_TYPEOF
+# -------------
+# Check if the C compiler understands typeof or a variant.  Define
+# HAVE_TYPEOF if so, and define 'typeof' to the actual key word.
+#
+AC_DEFUN([PGAC_C_TYPEOF],
+[AC_CACHE_CHECK(for typeof, pgac_cv_c_typeof,
+[pgac_cv_c_typeof=no
+for pgac_kw in typeof __typeof__ decltype; do
+  AC_COMPILE_IFELSE([AC_LANG_PROGRAM([],
+[int x = 0;
+$pgac_kw(x) y;
+y = x;
+return y;])],
+[pgac_cv_c_typeof=$pgac_kw])
+  test "$pgac_cv_c_typeof" != no && break
+done])
+if test "$pgac_cv_c_typeof" != no; then
+  AC_DEFINE(HAVE_TYPEOF, 1,
+            [Define to 1 if your compiler understands `typeof' or something similar.])
+  if test "$pgac_cv_c_typeof" != typeof; then
+    AC_DEFINE(typeof, $pgac_cv_c_typeof, [Define to how the compiler spells `typeof'.])
+  fi
+fi])# PGAC_C_TYPEOF
+
+
+
 # PGAC_C_TYPES_COMPATIBLE
 # -----------------------
 # Check if the C compiler understands __builtin_types_compatible_p,

configure

@@ -11667,6 +11667,46 @@ if test x"$pgac_cv__static_assert" = xyes ; then
 
 $as_echo "#define HAVE__STATIC_ASSERT 1" >>confdefs.h
 
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for typeof" >&5
+$as_echo_n "checking for typeof... " >&6; }
+if ${pgac_cv_c_typeof+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  pgac_cv_c_typeof=no
+for pgac_kw in typeof __typeof__ decltype; do
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+int x = 0;
+$pgac_kw(x) y;
+y = x;
+return y;
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  pgac_cv_c_typeof=$pgac_kw
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+  test "$pgac_cv_c_typeof" != no && break
+done
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_c_typeof" >&5
+$as_echo "$pgac_cv_c_typeof" >&6; }
+if test "$pgac_cv_c_typeof" != no; then
+
+$as_echo "#define HAVE_TYPEOF 1" >>confdefs.h
+
+  if test "$pgac_cv_c_typeof" != typeof; then
+
+$as_echo "#define typeof \$pgac_cv_c_typeof" >>confdefs.h
+
+  fi
 fi
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for __builtin_types_compatible_p" >&5
 $as_echo_n "checking for __builtin_types_compatible_p... " >&6; }

configure.in

@@ -1330,6 +1330,7 @@ AC_C_FLEXIBLE_ARRAY_MEMBER
 PGAC_C_SIGNED
 PGAC_C_FUNCNAME_SUPPORT
 PGAC_C_STATIC_ASSERT
+PGAC_C_TYPEOF
 PGAC_C_TYPES_COMPATIBLE
 PGAC_C_BUILTIN_BSWAP32
 PGAC_C_BUILTIN_BSWAP64

src/backend/bootstrap/bootstrap.c

@@ -1082,11 +1082,11 @@ index_register(Oid heap,
 
 	memcpy(newind->il_info, indexInfo, sizeof(IndexInfo));
 	/* expressions will likely be null, but may as well copy it */
-	newind->il_info->ii_Expressions = (List *)
+	newind->il_info->ii_Expressions =
 		copyObject(indexInfo->ii_Expressions);
 	newind->il_info->ii_ExpressionsState = NIL;
 	/* predicate will likely be null, but may as well copy it */
-	newind->il_info->ii_Predicate = (List *)
+	newind->il_info->ii_Predicate =
 		copyObject(indexInfo->ii_Predicate);
 	newind->il_info->ii_PredicateState = NULL;
 	/* no exclusion constraints at bootstrap time, so no need to copy */

src/backend/commands/copy.c

@@ -1470,7 +1470,7 @@ BeginCopy(ParseState *pstate,
 		 * function and is executed repeatedly.  (See also the same hack in
 		 * DECLARE CURSOR and PREPARE.)  XXX FIXME someday.
 		 */
-		rewritten = pg_analyze_and_rewrite((RawStmt *) copyObject(raw_query),
+		rewritten = pg_analyze_and_rewrite(copyObject(raw_query),
 										   pstate->p_sourcetext, NULL, 0);
 
 		/* check that we got back something we can work with */

src/backend/commands/createas.c

@@ -315,7 +315,7 @@ ExecCreateTableAs(CreateTableAsStmt *stmt, const char *queryString,
 		 * and is executed repeatedly.  (See also the same hack in EXPLAIN and
 		 * PREPARE.)
 		 */
-		rewritten = QueryRewrite((Query *) copyObject(query));
+		rewritten = QueryRewrite(copyObject(query));
 
 		/* SELECT should never rewrite to more or less than one SELECT query */
 		if (list_length(rewritten) != 1)

src/backend/commands/event_trigger.c

@@ -1869,7 +1869,7 @@ EventTriggerCollectAlterOpFam(AlterOpFamilyStmt *stmt, Oid opfamoid,
 					 OperatorFamilyRelationId, opfamoid);
 	command->d.opfam.operators = operators;
 	command->d.opfam.procedures = procedures;
-	command->parsetree = copyObject(stmt);
+	command->parsetree = (Node *) copyObject(stmt);
 
 	currentEventTriggerState->commandList =
 		lappend(currentEventTriggerState->commandList, command);
@@ -1902,7 +1902,7 @@ EventTriggerCollectCreateOpClass(CreateOpClassStmt *stmt, Oid opcoid,
 					 OperatorClassRelationId, opcoid);
 	command->d.createopc.operators = operators;
 	command->d.createopc.procedures = procedures;
-	command->parsetree = copyObject(stmt);
+	command->parsetree = (Node *) copyObject(stmt);
 
 	currentEventTriggerState->commandList =
 		lappend(currentEventTriggerState->commandList, command);
@@ -1937,7 +1937,7 @@ EventTriggerCollectAlterTSConfig(AlterTSConfigurationStmt *stmt, Oid cfgId,
 	command->d.atscfg.dictIds = palloc(sizeof(Oid) * ndicts);
 	memcpy(command->d.atscfg.dictIds, dictIds, sizeof(Oid) * ndicts);
 	command->d.atscfg.ndicts = ndicts;
-	command->parsetree = copyObject(stmt);
+	command->parsetree = (Node *) copyObject(stmt);
 
 	currentEventTriggerState->commandList =
 		lappend(currentEventTriggerState->commandList, command);
@@ -1967,7 +1967,7 @@ EventTriggerCollectAlterDefPrivs(AlterDefaultPrivilegesStmt *stmt)
 	command->type = SCT_AlterDefaultPrivileges;
 	command->d.defprivs.objtype = stmt->action->objtype;
 	command->in_extension = creating_extension;
-	command->parsetree = copyObject(stmt);
+	command->parsetree = (Node *) copyObject(stmt);
 
 	currentEventTriggerState->commandList =
 		lappend(currentEventTriggerState->commandList, command);

src/backend/commands/prepare.c

@@ -352,7 +352,7 @@ EvaluateParams(PreparedStatement *pstmt, List *params,
 	 * We have to run parse analysis for the expressions.  Since the parser is
 	 * not cool about scribbling on its input, copy first.
 	 */
-	params = (List *) copyObject(params);
+	params = copyObject(params);
 
 	pstate = make_parsestate(NULL);
 	pstate->p_sourcetext = queryString;
@@ -554,7 +554,7 @@ FetchPreparedStatementTargetList(PreparedStatement *stmt)
 	tlist = CachedPlanGetTargetList(stmt->plansource);
 
 	/* Copy into caller's context in case plan gets invalidated */
-	return (List *) copyObject(tlist);
+	return copyObject(tlist);
 }
 
 /*

src/backend/commands/view.c

@@ -373,7 +373,7 @@ UpdateRangeTableOfViewParse(Oid viewOid, Query *viewParse)
 	 * Var node twice.  copyObject will expand any multiply-referenced subtree
 	 * into multiple copies.
 	 */
-	viewParse = (Query *) copyObject(viewParse);
+	viewParse = copyObject(viewParse);
 
 	/* Create a dummy ParseState for addRangeTableEntryForRelation */
 	pstate = make_parsestate(NULL);

src/backend/nodes/copyfuncs.c

@@ -43,7 +43,7 @@
 
 /* Copy a field that is a pointer to some kind of Node or Node tree */
 #define COPY_NODE_FIELD(fldname) \
-	(newnode->fldname = copyObject(from->fldname))
+	(newnode->fldname = copyObjectImpl(from->fldname))
 
 /* Copy a field that is a pointer to a Bitmapset */
 #define COPY_BITMAPSET_FIELD(fldname) \
@@ -4507,7 +4507,7 @@ _copyDropSubscriptionStmt(const DropSubscriptionStmt *from)
  */
 #define COPY_NODE_CELL(new, old)					\
 	(new) = (ListCell *) palloc(sizeof(ListCell));	\
-	lfirst(new) = copyObject(lfirst(old));
+	lfirst(new) = copyObjectImpl(lfirst(old));
 
 static List *
 _copyList(const List *from)
@@ -4610,13 +4610,13 @@ _copyForeignKeyCacheInfo(const ForeignKeyCacheInfo *from)
 
 
 /*
- * copyObject
+ * copyObjectImpl -- implementation of copyObject(); see nodes/nodes.h
  *
  * Create a copy of a Node tree or list.  This is a "deep" copy: all
  * substructure is copied too, recursively.
  */
 void *
-copyObject(const void *from)
+copyObjectImpl(const void *from)
 {
 	void	   *retval;
 

src/backend/optimizer/path/indxpath.c

@@ -4004,9 +4004,9 @@ adjust_rowcompare_for_index(RowCompareExpr *clause,
 									   matching_cols);
 		rc->inputcollids = list_truncate(list_copy(clause->inputcollids),
 										 matching_cols);
-		rc->largs = list_truncate((List *) copyObject(clause->largs),
+		rc->largs = list_truncate(copyObject(clause->largs),
 								  matching_cols);
-		rc->rargs = list_truncate((List *) copyObject(clause->rargs),
+		rc->rargs = list_truncate(copyObject(clause->rargs),
 								  matching_cols);
 		return (Expr *) rc;
 	}

src/backend/optimizer/plan/createplan.c

@@ -1275,7 +1275,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 
 	foreach(l, uniq_exprs)
 	{
-		Node	   *uniqexpr = lfirst(l);
+		Expr	   *uniqexpr = lfirst(l);
 		TargetEntry *tle;
 
 		tle = tlist_member(uniqexpr, newtlist);
@@ -1318,7 +1318,7 @@ create_unique_plan(PlannerInfo *root, UniquePath *best_path, int flags)
 	groupColPos = 0;
 	foreach(l, uniq_exprs)
 	{
-		Node	   *uniqexpr = lfirst(l);
+		Expr	   *uniqexpr = lfirst(l);
 		TargetEntry *tle;
 
 		tle = tlist_member(uniqexpr, newtlist);
@@ -4318,7 +4318,7 @@ process_subquery_nestloop_params(PlannerInfo *root, List *subplan_params)
 				/* No, so add it */
 				nlp = makeNode(NestLoopParam);
 				nlp->paramno = pitem->paramId;
-				nlp->paramval = copyObject(phv);
+				nlp->paramval = (Var *) copyObject(phv);
 				root->curOuterParams = lappend(root->curOuterParams, nlp);
 			}
 		}

src/backend/optimizer/plan/initsplan.c

@@ -2306,8 +2306,8 @@ process_implied_equality(PlannerInfo *root,
 	clause = make_opclause(opno,
 						   BOOLOID,		/* opresulttype */
 						   false,		/* opretset */
-						   (Expr *) copyObject(item1),
+						   copyObject(item1),
-						   (Expr *) copyObject(item2),
+						   copyObject(item2),
 						   InvalidOid,
 						   collation);
 
@@ -2369,8 +2369,8 @@ build_implied_join_equality(Oid opno,
 	clause = make_opclause(opno,
 						   BOOLOID,		/* opresulttype */
 						   false,		/* opretset */
-						   (Expr *) copyObject(item1),
+						   copyObject(item1),
-						   (Expr *) copyObject(item2),
+						   copyObject(item2),
 						   InvalidOid,
 						   collation);
 

src/backend/optimizer/plan/planagg.c

@@ -369,11 +369,11 @@ build_minmax_path(PlannerInfo *root, MinMaxAggInfo *mminfo,
 	subroot->outer_params = NULL;
 	subroot->init_plans = NIL;
 
-	subroot->parse = parse = (Query *) copyObject(root->parse);
+	subroot->parse = parse = copyObject(root->parse);
 	IncrementVarSublevelsUp((Node *) parse, 1, 1);
 
 	/* append_rel_list might contain outer Vars? */
-	subroot->append_rel_list = (List *) copyObject(root->append_rel_list);
+	subroot->append_rel_list = copyObject(root->append_rel_list);
 	IncrementVarSublevelsUp((Node *) subroot->append_rel_list, 1, 1);
 	/* There shouldn't be any OJ info to translate, as yet */
 	Assert(subroot->join_info_list == NIL);

src/backend/optimizer/plan/planner.c

@@ -1157,7 +1157,7 @@ inheritance_planner(PlannerInfo *root)
 		 * executor doesn't need to see the modified copies --- we can just
 		 * pass it the original rowMarks list.)
 		 */
-		subroot->rowMarks = (List *) copyObject(root->rowMarks);
+		subroot->rowMarks = copyObject(root->rowMarks);
 
 		/*
 		 * The append_rel_list likewise might contain references to subquery
@@ -1179,7 +1179,7 @@ inheritance_planner(PlannerInfo *root)
 				AppendRelInfo *appinfo2 = (AppendRelInfo *) lfirst(lc2);
 
 				if (bms_is_member(appinfo2->child_relid, modifiableARIindexes))
-					appinfo2 = (AppendRelInfo *) copyObject(appinfo2);
+					appinfo2 = copyObject(appinfo2);
 
 				subroot->append_rel_list = lappend(subroot->append_rel_list,
 												   appinfo2);

src/backend/optimizer/plan/setrefs.c

@@ -111,10 +111,10 @@ static Var *search_indexed_tlist_for_var(Var *var,
 							 indexed_tlist *itlist,
 							 Index newvarno,
 							 int rtoffset);
-static Var *search_indexed_tlist_for_non_var(Node *node,
+static Var *search_indexed_tlist_for_non_var(Expr *node,
 								 indexed_tlist *itlist,
 								 Index newvarno);
-static Var *search_indexed_tlist_for_sortgroupref(Node *node,
+static Var *search_indexed_tlist_for_sortgroupref(Expr *node,
 									  Index sortgroupref,
 									  indexed_tlist *itlist,
 									  Index newvarno);
@@ -1440,7 +1440,7 @@ fix_param_node(PlannerInfo *root, Param *p)
 			elog(ERROR, "unexpected PARAM_MULTIEXPR ID: %d", p->paramid);
 		return copyObject(list_nth(params, colno - 1));
 	}
-	return copyObject(p);
+	return (Node *) copyObject(p);
 }
 
 /*
@@ -1727,7 +1727,7 @@ set_upper_references(PlannerInfo *root, Plan *plan, int rtoffset)
 		if (tle->ressortgroupref != 0 && !IsA(tle->expr, Var))
 		{
 			newexpr = (Node *)
-				search_indexed_tlist_for_sortgroupref((Node *) tle->expr,
+				search_indexed_tlist_for_sortgroupref(tle->expr,
 													  tle->ressortgroupref,
 													  subplan_itlist,
 													  OUTER_VAR);
@@ -1810,7 +1810,7 @@ convert_combining_aggrefs(Node *node, void *context)
 		 */
 		child_agg->args = NIL;
 		child_agg->aggfilter = NULL;
-		parent_agg = (Aggref *) copyObject(child_agg);
+		parent_agg = copyObject(child_agg);
 		child_agg->args = orig_agg->args;
 		child_agg->aggfilter = orig_agg->aggfilter;
 
@@ -2054,7 +2054,7 @@ search_indexed_tlist_for_var(Var *var, indexed_tlist *itlist,
  * so there's a correctness reason not to call it unless that's set.
  */
 static Var *
-search_indexed_tlist_for_non_var(Node *node,
+search_indexed_tlist_for_non_var(Expr *node,
 								 indexed_tlist *itlist, Index newvarno)
 {
 	TargetEntry *tle;
@@ -2095,7 +2095,7 @@ search_indexed_tlist_for_non_var(Node *node,
  * And it's also faster than search_indexed_tlist_for_non_var.
  */
 static Var *
-search_indexed_tlist_for_sortgroupref(Node *node,
+search_indexed_tlist_for_sortgroupref(Expr *node,
 									  Index sortgroupref,
 									  indexed_tlist *itlist,
 									  Index newvarno)
@@ -2229,7 +2229,7 @@ fix_join_expr_mutator(Node *node, fix_join_expr_context *context)
 		/* See if the PlaceHolderVar has bubbled up from a lower plan node */
 		if (context->outer_itlist && context->outer_itlist->has_ph_vars)
 		{
-			newvar = search_indexed_tlist_for_non_var((Node *) phv,
+			newvar = search_indexed_tlist_for_non_var((Expr *) phv,
 													  context->outer_itlist,
 													  OUTER_VAR);
 			if (newvar)
@@ -2237,7 +2237,7 @@ fix_join_expr_mutator(Node *node, fix_join_expr_context *context)
 		}
 		if (context->inner_itlist && context->inner_itlist->has_ph_vars)
 		{
-			newvar = search_indexed_tlist_for_non_var((Node *) phv,
+			newvar = search_indexed_tlist_for_non_var((Expr *) phv,
 													  context->inner_itlist,
 													  INNER_VAR);
 			if (newvar)
@@ -2252,7 +2252,7 @@ fix_join_expr_mutator(Node *node, fix_join_expr_context *context)
 	/* Try matching more complex expressions too, if tlists have any */
 	if (context->outer_itlist && context->outer_itlist->has_non_vars)
 	{
-		newvar = search_indexed_tlist_for_non_var(node,
+		newvar = search_indexed_tlist_for_non_var((Expr *) node,
 												  context->outer_itlist,
 												  OUTER_VAR);
 		if (newvar)
@@ -2260,7 +2260,7 @@ fix_join_expr_mutator(Node *node, fix_join_expr_context *context)
 	}
 	if (context->inner_itlist && context->inner_itlist->has_non_vars)
 	{
-		newvar = search_indexed_tlist_for_non_var(node,
+		newvar = search_indexed_tlist_for_non_var((Expr *) node,
 												  context->inner_itlist,
 												  INNER_VAR);
 		if (newvar)
@@ -2344,7 +2344,7 @@ fix_upper_expr_mutator(Node *node, fix_upper_expr_context *context)
 		/* See if the PlaceHolderVar has bubbled up from a lower plan node */
 		if (context->subplan_itlist->has_ph_vars)
 		{
-			newvar = search_indexed_tlist_for_non_var((Node *) phv,
+			newvar = search_indexed_tlist_for_non_var((Expr *) phv,
 													  context->subplan_itlist,
 													  context->newvarno);
 			if (newvar)
@@ -2380,7 +2380,7 @@ fix_upper_expr_mutator(Node *node, fix_upper_expr_context *context)
 	/* Try matching more complex expressions too, if tlist has any */
 	if (context->subplan_itlist->has_non_vars)
 	{
-		newvar = search_indexed_tlist_for_non_var(node,
+		newvar = search_indexed_tlist_for_non_var((Expr *) node,
 												  context->subplan_itlist,
 												  context->newvarno);
 		if (newvar)

src/backend/optimizer/plan/subselect.c

@@ -125,7 +125,7 @@ assign_param_for_var(PlannerInfo *root, Var *var)
 	}
 
 	/* Nope, so make a new one */
-	var = (Var *) copyObject(var);
+	var = copyObject(var);
 	var->varlevelsup = 0;
 
 	pitem = makeNode(PlannerParamItem);
@@ -224,7 +224,7 @@ assign_param_for_placeholdervar(PlannerInfo *root, PlaceHolderVar *phv)
 	}
 
 	/* Nope, so make a new one */
-	phv = (PlaceHolderVar *) copyObject(phv);
+	phv = copyObject(phv);
 	if (phv->phlevelsup != 0)
 	{
 		IncrementVarSublevelsUp((Node *) phv, -((int) phv->phlevelsup), 0);
@@ -316,7 +316,7 @@ replace_outer_agg(PlannerInfo *root, Aggref *agg)
 	 * It does not seem worthwhile to try to match duplicate outer aggs. Just
 	 * make a new slot every time.
 	 */
-	agg = (Aggref *) copyObject(agg);
+	agg = copyObject(agg);
 	IncrementVarSublevelsUp((Node *) agg, -((int) agg->agglevelsup), 0);
 	Assert(agg->agglevelsup == 0);
 
@@ -358,7 +358,7 @@ replace_outer_grouping(PlannerInfo *root, GroupingFunc *grp)
 	 * It does not seem worthwhile to try to match duplicate outer aggs. Just
 	 * make a new slot every time.
 	 */
-	grp = (GroupingFunc *) copyObject(grp);
+	grp = copyObject(grp);
 	IncrementVarSublevelsUp((Node *) grp, -((int) grp->agglevelsup), 0);
 	Assert(grp->agglevelsup == 0);
 
@@ -491,7 +491,7 @@ make_subplan(PlannerInfo *root, Query *orig_subquery,
 	 * same sub-Query node, but the planner wants to scribble on the Query.
 	 * Try to clean this up when we do querytree redesign...
 	 */
-	subquery = (Query *) copyObject(orig_subquery);
+	subquery = copyObject(orig_subquery);
 
 	/*
 	 * If it's an EXISTS subplan, we might be able to simplify it.
@@ -568,7 +568,7 @@ make_subplan(PlannerInfo *root, Query *orig_subquery,
 		List	   *paramIds;
 
 		/* Make a second copy of the original subquery */
-		subquery = (Query *) copyObject(orig_subquery);
+		subquery = copyObject(orig_subquery);
 		/* and re-simplify */
 		simple_exists = simplify_EXISTS_query(root, subquery);
 		Assert(simple_exists);
@@ -1431,7 +1431,7 @@ convert_EXISTS_sublink_to_join(PlannerInfo *root, SubLink *sublink,
 	 * Copy the subquery so we can modify it safely (see comments in
 	 * make_subplan).
 	 */
-	subselect = (Query *) copyObject(subselect);
+	subselect = copyObject(subselect);
 
 	/*
 	 * See if the subquery can be simplified based on the knowledge that it's

src/backend/optimizer/prep/prepjointree.c

@@ -1592,7 +1592,7 @@ pull_up_simple_values(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte)
 	 * Need a modifiable copy of the VALUES list to hack on, just in case it's
 	 * multiply referenced.
 	 */
-	values_list = (List *) copyObject(linitial(rte->values_lists));
+	values_list = copyObject(linitial(rte->values_lists));
 
 	/*
 	 * The VALUES RTE can't contain any Vars of level zero, let alone any that
@@ -2128,7 +2128,7 @@ pullup_replace_vars_callback(Var *var,
 				 varattno);
 
 		/* Make a copy of the tlist item to return */
-		newnode = copyObject(tle->expr);
+		newnode = (Node *) copyObject(tle->expr);
 
 		/* Insert PlaceHolderVar if needed */
 		if (rcon->need_phvs)

src/backend/optimizer/prep/preptlist.c

@@ -180,7 +180,7 @@ preprocess_targetlist(PlannerInfo *root, List *tlist)
 				var->varno == result_relation)
 				continue;		/* don't need it */
 
-			if (tlist_member((Node *) var, tlist))
+			if (tlist_member((Expr *) var, tlist))
 				continue;		/* already got it */
 
 			tle = makeTargetEntry((Expr *) var,

src/backend/optimizer/prep/prepunion.c

@@ -1274,7 +1274,7 @@ generate_append_tlist(List *colTypes, List *colCollations,
 static List *
 generate_setop_grouplist(SetOperationStmt *op, List *targetlist)
 {
-	List	   *grouplist = (List *) copyObject(op->groupClauses);
+	List	   *grouplist = copyObject(op->groupClauses);
 	ListCell   *lg;
 	ListCell   *lt;
 
@@ -1879,7 +1879,7 @@ adjust_appendrel_attrs_mutator(Node *node,
 
 					rte = rt_fetch(appinfo->parent_relid,
 								   context->root->parse->rtable);
-					fields = (List *) copyObject(appinfo->translated_vars);
+					fields = copyObject(appinfo->translated_vars);
 					rowexpr = makeNode(RowExpr);
 					rowexpr->args = fields;
 					rowexpr->row_typeid = var->vartype;

src/backend/optimizer/util/tlist.c

@@ -51,7 +51,7 @@ static bool split_pathtarget_walker(Node *node,
  *	  equal() to the given expression.  Result is NULL if no such member.
  */
 TargetEntry *
-tlist_member(Node *node, List *targetlist)
+tlist_member(Expr *node, List *targetlist)
 {
 	ListCell   *temp;
 
@@ -72,12 +72,12 @@ tlist_member(Node *node, List *targetlist)
  *	  involving binary-compatible sort operations.
  */
 TargetEntry *
-tlist_member_ignore_relabel(Node *node, List *targetlist)
+tlist_member_ignore_relabel(Expr *node, List *targetlist)
 {
 	ListCell   *temp;
 
 	while (node && IsA(node, RelabelType))
-		node = (Node *) ((RelabelType *) node)->arg;
+		node = ((RelabelType *) node)->arg;
 
 	foreach(temp, targetlist)
 	{
@@ -139,7 +139,7 @@ add_to_flat_tlist(List *tlist, List *exprs)
 
 	foreach(lc, exprs)
 	{
-		Node	   *expr = (Node *) lfirst(lc);
+		Expr	   *expr = (Expr *) lfirst(lc);
 
 		if (!tlist_member(expr, tlist))
 		{
@@ -762,7 +762,7 @@ apply_pathtarget_labeling_to_tlist(List *tlist, PathTarget *target)
 			if (expr && IsA(expr, Var))
 				tle = tlist_member_match_var((Var *) expr, tlist);
 			else
-				tle = tlist_member((Node *) expr, tlist);
+				tle = tlist_member(expr, tlist);
 
 			/*
 			 * Complain if noplace for the sortgrouprefs label, or if we'd
@@ -999,7 +999,7 @@ split_pathtarget_at_srfs(PlannerInfo *root,
 
 				foreach(lcx, input_srfs)
 				{
-					Node	   *srf = (Node *) lfirst(lcx);
+					Expr	   *srf = (Expr *) lfirst(lcx);
 
 					if (list_member(prev_level_tlist, srf))
 						add_new_column_to_pathtarget(ntarget, copyObject(srf));

src/backend/parser/analyze.c

@@ -2548,7 +2548,7 @@ transformCreateTableAsStmt(ParseState *pstate, CreateTableAsStmt *stmt)
 		 * in the IntoClause because that's where intorel_startup() can
 		 * conveniently get it from.
 		 */
-		stmt->into->viewQuery = copyObject(query);
+		stmt->into->viewQuery = (Node *) copyObject(query);
 	}
 
 	/* represent the command as a utility Query */

src/backend/parser/gram.y

@@ -15599,7 +15599,7 @@ TableFuncTypeName(List *columns)
 	{
 		FunctionParameter *p = (FunctionParameter *) linitial(columns);
 
-		result = (TypeName *) copyObject(p->argType);
+		result = copyObject(p->argType);
 	}
 	else
 		result = SystemTypeName("record");

src/backend/parser/parse_clause.c

@@ -348,7 +348,7 @@ transformJoinUsingClause(ParseState *pstate,
 
 		/* Now create the lvar = rvar join condition */
 		e = makeSimpleA_Expr(AEXPR_OP, "=",
-							 copyObject(lvar), copyObject(rvar),
+							 (Node *) copyObject(lvar), (Node *) copyObject(rvar),
 							 -1);
 
 		/* Prepare to combine into an AND clause, if multiple join columns */

src/backend/parser/parse_expr.c

@@ -1255,7 +1255,7 @@ transformAExprIn(ParseState *pstate, A_Expr *a)
 			/* ROW() op ROW() is handled specially */
 			cmp = make_row_comparison_op(pstate,
 										 a->name,
-							  (List *) copyObject(((RowExpr *) lexpr)->args),
+										 copyObject(((RowExpr *) lexpr)->args),
 										 ((RowExpr *) rexpr)->args,
 										 a->location);
 		}

src/backend/parser/parse_relation.c

@@ -1804,7 +1804,7 @@ addRangeTableEntryForJoin(ParseState *pstate,
 	rte->joinaliasvars = aliasvars;
 	rte->alias = alias;
 
-	eref = alias ? (Alias *) copyObject(alias) : makeAlias("unnamed_join", NIL);
+	eref = alias ? copyObject(alias) : makeAlias("unnamed_join", NIL);
 	numaliases = list_length(eref->colnames);
 
 	/* fill in any unspecified alias columns */

src/backend/parser/parse_utilcmd.c

@@ -167,7 +167,7 @@ transformCreateStmt(CreateStmt *stmt, const char *queryString)
 	 * We must not scribble on the passed-in CreateStmt, so copy it.  (This is
 	 * overkill, but easy.)
 	 */
-	stmt = (CreateStmt *) copyObject(stmt);
+	stmt = copyObject(stmt);
 
 	/* Set up pstate */
 	pstate = make_parsestate(NULL);
@@ -2107,7 +2107,7 @@ transformIndexStmt(Oid relid, IndexStmt *stmt, const char *queryString)
 	 * We must not scribble on the passed-in IndexStmt, so copy it.  (This is
 	 * overkill, but easy.)
 	 */
-	stmt = (IndexStmt *) copyObject(stmt);
+	stmt = copyObject(stmt);
 
 	/* Set up pstate */
 	pstate = make_parsestate(NULL);
@@ -2521,7 +2521,7 @@ transformAlterTableStmt(Oid relid, AlterTableStmt *stmt,
 	 * We must not scribble on the passed-in AlterTableStmt, so copy it. (This
 	 * is overkill, but easy.)
 	 */
-	stmt = (AlterTableStmt *) copyObject(stmt);
+	stmt = copyObject(stmt);
 
 	/* Caller is responsible for locking the relation */
 	rel = relation_open(relid, NoLock);

src/backend/rewrite/rewriteHandler.c

@@ -349,8 +349,8 @@ rewriteRuleAction(Query *parsetree,
 	 * Make modifiable copies of rule action and qual (what we're passed are
 	 * the stored versions in the relcache; don't touch 'em!).
 	 */
-	rule_action = (Query *) copyObject(rule_action);
+	rule_action = copyObject(rule_action);
-	rule_qual = (Node *) copyObject(rule_qual);
+	rule_qual = copyObject(rule_qual);
 
 	/*
 	 * Acquire necessary locks and fix any deleted JOIN RTE entries.
@@ -408,7 +408,7 @@ rewriteRuleAction(Query *parsetree,
 	 * that rule action's rtable is separate and shares no substructure with
 	 * the main rtable.  Hence do a deep copy here.
 	 */
-	sub_action->rtable = list_concat((List *) copyObject(parsetree->rtable),
+	sub_action->rtable = list_concat(copyObject(parsetree->rtable),
 									 sub_action->rtable);
 
 	/*
@@ -1897,7 +1897,7 @@ CopyAndAddInvertedQual(Query *parsetree,
 					   CmdType event)
 {
 	/* Don't scribble on the passed qual (it's in the relcache!) */
-	Node	   *new_qual = (Node *) copyObject(rule_qual);
+	Node	   *new_qual = copyObject(rule_qual);
 	acquireLocksOnSubLinks_context context;
 
 	context.for_execute = true;

src/backend/rewrite/rewriteManip.c

@@ -1412,11 +1412,11 @@ ReplaceVarsFromTargetList_callback(Var *var,
 	else
 	{
 		/* Make a copy of the tlist item to return */
-		Node	   *newnode = copyObject(tle->expr);
+		Expr	   *newnode = copyObject(tle->expr);
 
 		/* Must adjust varlevelsup if tlist item is from higher query */
 		if (var->varlevelsup > 0)
-			IncrementVarSublevelsUp(newnode, var->varlevelsup, 0);
+			IncrementVarSublevelsUp((Node *) newnode, var->varlevelsup, 0);
 
 		/*
 		 * Check to see if the tlist item contains a PARAM_MULTIEXPR Param,
@@ -1428,12 +1428,12 @@ ReplaceVarsFromTargetList_callback(Var *var,
 		 * create semantic oddities that users of rules would probably prefer
 		 * not to cope with.  So treat it as an unimplemented feature.
 		 */
-		if (contains_multiexpr_param(newnode, NULL))
+		if (contains_multiexpr_param((Node *) newnode, NULL))
 			ereport(ERROR,
 					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 					 errmsg("NEW variables in ON UPDATE rules cannot reference columns that are part of a multiple assignment in the subject UPDATE command")));
 
-		return newnode;
+		return (Node *) newnode;
 	}
 }
 

src/backend/tcop/postgres.c

@@ -616,7 +616,7 @@ pg_parse_query(const char *query_string)
 #ifdef COPY_PARSE_PLAN_TREES
 	/* Optional debugging check: pass raw parsetrees through copyObject() */
 	{
-		List	   *new_list = (List *) copyObject(raw_parsetree_list);
+		List	   *new_list = copyObject(raw_parsetree_list);
 
 		/* This checks both copyObject() and the equal() routines... */
 		if (!equal(new_list, raw_parsetree_list))
@@ -756,7 +756,7 @@ pg_rewrite_query(Query *query)
 	{
 		List	   *new_list;
 
-		new_list = (List *) copyObject(querytree_list);
+		new_list = copyObject(querytree_list);
 		/* This checks both copyObject() and the equal() routines... */
 		if (!equal(new_list, querytree_list))
 			elog(WARNING, "copyObject() failed to produce equal parse tree");
@@ -803,7 +803,7 @@ pg_plan_query(Query *querytree, int cursorOptions, ParamListInfo boundParams)
 #ifdef COPY_PARSE_PLAN_TREES
 	/* Optional debugging check: pass plan output through copyObject() */
 	{
-		PlannedStmt *new_plan = (PlannedStmt *) copyObject(plan);
+		PlannedStmt *new_plan = copyObject(plan);
 
 		/*
 		 * equal() currently does not have routines to compare Plan nodes, so

src/backend/utils/cache/plancache.c

@@ -361,7 +361,7 @@ CompleteCachedPlan(CachedPlanSource *plansource,
 												  "CachedPlanQuery",
 												  ALLOCSET_START_SMALL_SIZES);
 		MemoryContextSwitchTo(querytree_context);
-		querytree_list = (List *) copyObject(querytree_list);
+		querytree_list = copyObject(querytree_list);
 	}
 
 	plansource->query_context = querytree_context;
@@ -734,7 +734,7 @@ RevalidateCachedQuery(CachedPlanSource *plansource)
 											  ALLOCSET_START_SMALL_SIZES);
 	oldcxt = MemoryContextSwitchTo(querytree_context);
 
-	qlist = (List *) copyObject(tlist);
+	qlist = copyObject(tlist);
 
 	/*
 	 * Use the planner machinery to extract dependencies.  Data is saved in
@@ -909,7 +909,7 @@ BuildCachedPlan(CachedPlanSource *plansource, List *qlist,
 	if (qlist == NIL)
 	{
 		if (!plansource->is_oneshot)
-			qlist = (List *) copyObject(plansource->query_list);
+			qlist = copyObject(plansource->query_list);
 		else
 			qlist = plansource->query_list;
 	}
@@ -953,7 +953,7 @@ BuildCachedPlan(CachedPlanSource *plansource, List *qlist,
 		 */
 		MemoryContextSwitchTo(plan_context);
 
-		plist = (List *) copyObject(plist);
+		plist = copyObject(plist);
 	}
 	else
 		plan_context = CurrentMemoryContext;
@@ -1367,9 +1367,9 @@ CopyCachedPlan(CachedPlanSource *plansource)
 											  "CachedPlanQuery",
 											  ALLOCSET_START_SMALL_SIZES);
 	MemoryContextSwitchTo(querytree_context);
-	newsource->query_list = (List *) copyObject(plansource->query_list);
+	newsource->query_list = copyObject(plansource->query_list);
-	newsource->relationOids = (List *) copyObject(plansource->relationOids);
+	newsource->relationOids = copyObject(plansource->relationOids);
-	newsource->invalItems = (List *) copyObject(plansource->invalItems);
+	newsource->invalItems = copyObject(plansource->invalItems);
 	if (plansource->search_path)
 		newsource->search_path = CopyOverrideSearchPath(plansource->search_path);
 	newsource->query_context = querytree_context;

src/backend/utils/cache/relcache.c

@@ -4697,7 +4697,7 @@ RelationGetIndexExpressions(Relation relation)
 
 	/* Quick exit if we already computed the result. */
 	if (relation->rd_indexprs)
-		return (List *) copyObject(relation->rd_indexprs);
+		return copyObject(relation->rd_indexprs);
 
 	/* Quick exit if there is nothing to do. */
 	if (relation->rd_indextuple == NULL ||
@@ -4733,7 +4733,7 @@ RelationGetIndexExpressions(Relation relation)
 
 	/* Now save a copy of the completed tree in the relcache entry. */
 	oldcxt = MemoryContextSwitchTo(relation->rd_indexcxt);
-	relation->rd_indexprs = (List *) copyObject(result);
+	relation->rd_indexprs = copyObject(result);
 	MemoryContextSwitchTo(oldcxt);
 
 	return result;
@@ -4760,7 +4760,7 @@ RelationGetIndexPredicate(Relation relation)
 
 	/* Quick exit if we already computed the result. */
 	if (relation->rd_indpred)
-		return (List *) copyObject(relation->rd_indpred);
+		return copyObject(relation->rd_indpred);
 
 	/* Quick exit if there is nothing to do. */
 	if (relation->rd_indextuple == NULL ||
@@ -4802,7 +4802,7 @@ RelationGetIndexPredicate(Relation relation)
 
 	/* Now save a copy of the completed tree in the relcache entry. */
 	oldcxt = MemoryContextSwitchTo(relation->rd_indexcxt);
-	relation->rd_indpred = (List *) copyObject(result);
+	relation->rd_indpred = copyObject(result);
 	MemoryContextSwitchTo(oldcxt);
 
 	return result;

src/include/nodes/nodes.h

@@ -610,7 +610,13 @@ extern int16 *readAttrNumberCols(int numCols);
 /*
  * nodes/copyfuncs.c
  */
-extern void *copyObject(const void *obj);
+extern void *copyObjectImpl(const void *obj);
+/* cast result back to argument type, if supported by compiler */
+#ifdef HAVE_TYPEOF
+#define copyObject(obj) ((typeof(obj)) copyObjectImpl(obj))
+#else
+#define copyObject(obj) copyObjectImpl(obj)
+#endif
 
 /*
  * nodes/equalfuncs.c

src/include/optimizer/tlist.h

@@ -17,8 +17,8 @@
 #include "nodes/relation.h"
 
 
-extern TargetEntry *tlist_member(Node *node, List *targetlist);
+extern TargetEntry *tlist_member(Expr *node, List *targetlist);
-extern TargetEntry *tlist_member_ignore_relabel(Node *node, List *targetlist);
+extern TargetEntry *tlist_member_ignore_relabel(Expr *node, List *targetlist);
 
 extern List *add_to_flat_tlist(List *tlist, List *exprs);
 

src/include/pg_config.h.in

@@ -603,6 +603,9 @@
 /* Define to 1 if you have the `towlower' function. */
 #undef HAVE_TOWLOWER
 
+/* Define to 1 if your compiler understands `typeof' or something similar. */
+#undef HAVE_TYPEOF
+
 /* Define to 1 if you have the external array `tzname'. */
 #undef HAVE_TZNAME
 
@@ -931,6 +934,9 @@
 /* Define to empty if the C compiler does not understand signed types. */
 #undef signed
 
+/* Define to how the compiler spells `typeof'. */
+#undef typeof
+
 /* Define to the type of an unsigned integer type wide enough to hold a
    pointer, if such a type exists, and if the system does not define it. */
 #undef uintptr_t

src/include/pg_config.h.win32

@@ -454,6 +454,9 @@
 /* Define to 1 if you have the `towlower' function. */
 #define HAVE_TOWLOWER 1
 
+/* Define to 1 if your compiler understands `typeof' or something similar. */
+#define HAVE_TYPEOF 1
+
 /* Define to 1 if you have the external array `tzname'. */
 /* #undef HAVE_TZNAME */
 
@@ -682,3 +685,6 @@
 
 /* Define to empty if the C compiler does not understand signed types. */
 /* #undef signed */
+
+/* Define to how the compiler spells `typeof'. */
+#define typeof decltype