Improve castNode notation by introducing list-extraction-specific variants.

This extends the castNode() notation introduced by commit 5bcab1114 to
provide, in one step, extraction of a list cell's pointer and coercion to
a concrete node type.  For example, "lfirst_node(Foo, lc)" is the same
as "castNode(Foo, lfirst(lc))".  Almost half of the uses of castNode
that have appeared so far include a list extraction call, so this is
pretty widely useful, and it saves a few more keystrokes compared to the
old way.

As with the previous patch, back-patch the addition of these macros to
pg_list.h, so that the notation will be available when back-patching.

Patch by me, after an idea of Andrew Gierth's.

Discussion: https://postgr.es/m/14197.1491841216@sss.pgh.pa.us

12 files changed, 23 insertions, 23 deletions

diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c
index 1f510c2819..52643d0ad6 100644
--- a/src/backend/optimizer/path/costsize.c
+++ b/src/backend/optimizer/path/costsize.c
@@ -757,7 +757,7 @@ extract_nonindex_conditions(List *qual_clauses, List *indexquals)
 
 	foreach(lc, qual_clauses)
 	{
-		RestrictInfo *rinfo = castNode(RestrictInfo, lfirst(lc));
+		RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
 
 		if (rinfo->pseudoconstant)
 			continue;			/* we may drop pseudoconstants here */
@@ -1990,7 +1990,7 @@ cost_windowagg(Path *path, PlannerInfo *root,
 	 */
 	foreach(lc, windowFuncs)
 	{
-		WindowFunc *wfunc = castNode(WindowFunc, lfirst(lc));
+		WindowFunc *wfunc = lfirst_node(WindowFunc, lc);
 		Cost		wfunccost;
 		QualCost	argcosts;
 
@@ -3066,7 +3066,7 @@ final_cost_hashjoin(PlannerInfo *root, HashPath *path,
 		innerbucketsize = 1.0;
 		foreach(hcl, hashclauses)
 		{
-			RestrictInfo *restrictinfo = castNode(RestrictInfo, lfirst(hcl));
+			RestrictInfo *restrictinfo = lfirst_node(RestrictInfo, hcl);
 			Selectivity thisbucketsize;
 
 			/*
@@ -3760,7 +3760,7 @@ compute_semi_anti_join_factors(PlannerInfo *root,
 		joinquals = NIL;
 		foreach(l, restrictlist)
 		{
-			RestrictInfo *rinfo = castNode(RestrictInfo, lfirst(l));
+			RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
 
 			if (!rinfo->is_pushed_down)
 				joinquals = lappend(joinquals, rinfo);
@@ -4192,7 +4192,7 @@ calc_joinrel_size_estimate(PlannerInfo *root,
 		/* Grovel through the clauses to separate into two lists */
 		foreach(l, restrictlist)
 		{
-			RestrictInfo *rinfo = castNode(RestrictInfo, lfirst(l));
+			RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
 
 			if (rinfo->is_pushed_down)
 				pushedquals = lappend(pushedquals, rinfo);
@@ -4568,7 +4568,7 @@ set_subquery_size_estimates(PlannerInfo *root, RelOptInfo *rel)
 	 */
 	foreach(lc, subroot->parse->targetList)
 	{
-		TargetEntry *te = castNode(TargetEntry, lfirst(lc));
+		TargetEntry *te = lfirst_node(TargetEntry, lc);
 		Node	   *texpr = (Node *) te->expr;
 		int32		item_width = 0;
 
diff --git a/src/backend/optimizer/path/indxpath.c b/src/backend/optimizer/path/indxpath.c
index cec9822cb7..6e4bae854a 100644
--- a/src/backend/optimizer/path/indxpath.c
+++ b/src/backend/optimizer/path/indxpath.c
@@ -1277,7 +1277,7 @@ generate_bitmap_or_paths(PlannerInfo *root, RelOptInfo *rel,
 
 	foreach(lc, clauses)
 	{
-		RestrictInfo *rinfo = castNode(RestrictInfo, lfirst(lc));
+		RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
 		List	   *pathlist;
 		Path	   *bitmapqual;
 		ListCell   *j;
@@ -2188,7 +2188,7 @@ match_clauses_to_index(IndexOptInfo *index,
 
 	foreach(lc, clauses)
 	{
-		RestrictInfo *rinfo = castNode(RestrictInfo, lfirst(lc));
+		RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
 
 		match_clause_to_index(index, rinfo, clauseset);
 	}
diff --git a/src/backend/optimizer/path/joinrels.c b/src/backend/optimizer/path/joinrels.c
index 6a0c67b9ab..5a68de3cc8 100644
--- a/src/backend/optimizer/path/joinrels.c
+++ b/src/backend/optimizer/path/joinrels.c
@@ -1250,7 +1250,7 @@ restriction_is_constant_false(List *restrictlist, bool only_pushed_down)
 	 */
 	foreach(lc, restrictlist)
 	{
-		RestrictInfo *rinfo = castNode(RestrictInfo, lfirst(lc));
+		RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
 
 		if (only_pushed_down && !rinfo->is_pushed_down)
 			continue;
diff --git a/src/backend/optimizer/plan/analyzejoins.c b/src/backend/optimizer/plan/analyzejoins.c
index cb283f686e..69b9be4d76 100644
--- a/src/backend/optimizer/plan/analyzejoins.c
+++ b/src/backend/optimizer/plan/analyzejoins.c
@@ -601,7 +601,7 @@ rel_is_distinct_for(PlannerInfo *root, RelOptInfo *rel, List *clause_list)
 		 */
 		foreach(l, clause_list)
 		{
-			RestrictInfo *rinfo = castNode(RestrictInfo, lfirst(l));
+			RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
 			Oid			op;
 			Var		   *var;
 
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 124fef78f5..717b78c161 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -2550,7 +2550,7 @@ create_indexscan_plan(PlannerInfo *root,
 	qpqual = NIL;
 	foreach(l, scan_clauses)
 	{
-		RestrictInfo *rinfo = castNode(RestrictInfo, lfirst(l));
+		RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
 
 		if (rinfo->pseudoconstant)
 			continue;			/* we may drop pseudoconstants here */
@@ -2710,7 +2710,7 @@ create_bitmap_scan_plan(PlannerInfo *root,
 	qpqual = NIL;
 	foreach(l, scan_clauses)
 	{
-		RestrictInfo *rinfo = castNode(RestrictInfo, lfirst(l));
+		RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
 		Node	   *clause = (Node *) rinfo->clause;
 
 		if (rinfo->pseudoconstant)
@@ -3867,7 +3867,7 @@ create_mergejoin_plan(PlannerInfo *root,
 	i = 0;
 	foreach(lc, best_path->path_mergeclauses)
 	{
-		RestrictInfo *rinfo = castNode(RestrictInfo, lfirst(lc));
+		RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc);
 		EquivalenceClass *oeclass;
 		EquivalenceClass *ieclass;
 		PathKey    *opathkey;
@@ -4414,7 +4414,7 @@ fix_indexqual_references(PlannerInfo *root, IndexPath *index_path)
 
 	forboth(lcc, index_path->indexquals, lci, index_path->indexqualcols)
 	{
-		RestrictInfo *rinfo = castNode(RestrictInfo, lfirst(lcc));
+		RestrictInfo *rinfo = lfirst_node(RestrictInfo, lcc);
 		int			indexcol = lfirst_int(lci);
 		Node	   *clause;
 
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 17cd683d85..4d5ee01b24 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -4631,7 +4631,7 @@ create_one_window_path(PlannerInfo *root,
 			window_target = copy_pathtarget(window_target);
 			foreach(lc2, wflists->windowFuncs[wc->winref])
 			{
-				WindowFunc *wfunc = castNode(WindowFunc, lfirst(lc2));
+				WindowFunc *wfunc = lfirst_node(WindowFunc, lc2);
 
 				add_column_to_pathtarget(window_target, (Expr *) wfunc, 0);
 				window_target->width += get_typavgwidth(wfunc->wintype, -1);
diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index cdb8e95deb..1278371b65 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -224,7 +224,7 @@ set_plan_references(PlannerInfo *root, Plan *plan)
 	 */
 	foreach(lc, root->rowMarks)
 	{
-		PlanRowMark *rc = castNode(PlanRowMark, lfirst(lc));
+		PlanRowMark *rc = lfirst_node(PlanRowMark, lc);
 		PlanRowMark *newrc;
 
 		/* flat copy is enough since all fields are scalars */
diff --git a/src/backend/optimizer/plan/subselect.c b/src/backend/optimizer/plan/subselect.c
index 87cc44d678..8d0d8aed66 100644
--- a/src/backend/optimizer/plan/subselect.c
+++ b/src/backend/optimizer/plan/subselect.c
@@ -433,7 +433,7 @@ get_first_col_type(Plan *plan, Oid *coltype, int32 *coltypmod,
 	/* In cases such as EXISTS, tlist might be empty; arbitrarily use VOID */
 	if (plan->targetlist)
 	{
-		TargetEntry *tent = castNode(TargetEntry, linitial(plan->targetlist));
+		TargetEntry *tent = linitial_node(TargetEntry, plan->targetlist);
 
 		if (!tent->resjunk)
 		{
diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c
index 881d85e26c..a1be858901 100644
--- a/src/backend/optimizer/prep/prepunion.c
+++ b/src/backend/optimizer/prep/prepunion.c
@@ -1750,7 +1750,7 @@ translate_col_privs(const Bitmapset *parent_privs,
 	attno = InvalidAttrNumber;
 	foreach(lc, translated_vars)
 	{
-		Var		   *var = castNode(Var, lfirst(lc));
+		Var		   *var = lfirst_node(Var, lc);
 
 		attno++;
 		if (var == NULL)		/* ignore dropped columns */
diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c
index 59d71c1b32..e196c5e2b5 100644
--- a/src/backend/optimizer/util/clauses.c
+++ b/src/backend/optimizer/util/clauses.c
@@ -3090,7 +3090,7 @@ eval_const_expressions_mutator(Node *node,
 				const_true_cond = false;
 				foreach(arg, caseexpr->args)
 				{
-					CaseWhen   *oldcasewhen = castNode(CaseWhen, lfirst(arg));
+					CaseWhen   *oldcasewhen = lfirst_node(CaseWhen, arg);
 					Node	   *casecond;
 					Node	   *caseresult;
 
diff --git a/src/backend/optimizer/util/orclauses.c b/src/backend/optimizer/util/orclauses.c
index 9cbcaedb75..b6867e3001 100644
--- a/src/backend/optimizer/util/orclauses.c
+++ b/src/backend/optimizer/util/orclauses.c
@@ -188,7 +188,7 @@ extract_or_clause(RestrictInfo *or_rinfo, RelOptInfo *rel)
 
 			foreach(lc2, andargs)
 			{
-				RestrictInfo *rinfo = castNode(RestrictInfo, lfirst(lc2));
+				RestrictInfo *rinfo = lfirst_node(RestrictInfo, lc2);
 
 				if (restriction_is_or_clause(rinfo))
 				{
diff --git a/src/backend/optimizer/util/restrictinfo.c b/src/backend/optimizer/util/restrictinfo.c
index 6f79f96654..e946290af5 100644
--- a/src/backend/optimizer/util/restrictinfo.c
+++ b/src/backend/optimizer/util/restrictinfo.c
@@ -335,7 +335,7 @@ get_actual_clauses(List *restrictinfo_list)
 
 	foreach(l, restrictinfo_list)
 	{
-		RestrictInfo *rinfo = castNode(RestrictInfo, lfirst(l));
+		RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
 
 		Assert(!rinfo->pseudoconstant);
 
@@ -359,7 +359,7 @@ extract_actual_clauses(List *restrictinfo_list,
 
 	foreach(l, restrictinfo_list)
 	{
-		RestrictInfo *rinfo = castNode(RestrictInfo, lfirst(l));
+		RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
 
 		if (rinfo->pseudoconstant == pseudoconstant)
 			result = lappend(result, rinfo->clause);
@@ -389,7 +389,7 @@ extract_actual_join_clauses(List *restrictinfo_list,
 
 	foreach(l, restrictinfo_list)
 	{
-		RestrictInfo *rinfo = castNode(RestrictInfo, lfirst(l));
+		RestrictInfo *rinfo = lfirst_node(RestrictInfo, l);
 
 		if (rinfo->is_pushed_down)
 		{