Fix oversight in new code for printing rangetable aliases.

In commit 11e131854f8231a21613f834c40fe9d046926387, I missed the case of
a CTE RTE that doesn't have a user-defined alias, but does have an
alias assigned by set_rtable_names().  Per report from Peter Eisentraut.

While at it, refactor slightly to reduce code duplication.

3 files changed, 56 insertions, 10 deletions

diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index c8d7d9c21b3..c3ede233bcd 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -6739,11 +6739,12 @@ get_from_clause_item(Node *jtnode, Query *query, deparse_context *context)
 		int			varno = ((RangeTblRef *) jtnode)->rtindex;
 		RangeTblEntry *rte = rt_fetch(varno, query->rtable);
 		char	   *refname = get_rtable_name(varno, context);
-		bool		gavealias = false;
+		bool		printalias;
 
 		if (rte->lateral)
 			appendStringInfoString(buf, "LATERAL ");
 
+		/* Print the FROM item proper */
 		switch (rte->rtekind)
 		{
 			case RTE_RELATION:
@@ -6776,11 +6777,12 @@ get_from_clause_item(Node *jtnode, Query *query, deparse_context *context)
 				break;
 		}
 
+		/* Print the relation alias, if needed */
+		printalias = false;
 		if (rte->alias != NULL)
 		{
 			/* Always print alias if user provided one */
-			appendStringInfo(buf, " %s", quote_identifier(refname));
-			gavealias = true;
+			printalias = true;
 		}
 		else if (rte->rtekind == RTE_RELATION)
 		{
@@ -6790,10 +6792,7 @@ get_from_clause_item(Node *jtnode, Query *query, deparse_context *context)
 			 * resolve a conflict).
 			 */
 			if (strcmp(refname, get_relation_name(rte->relid)) != 0)
-			{
-				appendStringInfo(buf, " %s", quote_identifier(refname));
-				gavealias = true;
-			}
+				printalias = true;
 		}
 		else if (rte->rtekind == RTE_FUNCTION)
 		{
@@ -6802,16 +6801,28 @@ get_from_clause_item(Node *jtnode, Query *query, deparse_context *context)
 			 * renaming of the function and/or instability of the
 			 * FigureColname rules for things that aren't simple functions.
 			 */
-			appendStringInfo(buf, " %s", quote_identifier(refname));
-			gavealias = true;
+			printalias = true;
+		}
+		else if (rte->rtekind == RTE_CTE)
+		{
+			/*
+			 * No need to print alias if it's same as CTE name (this would
+			 * normally be the case, but not if set_rtable_names had to
+			 * resolve a conflict).
+			 */
+			if (strcmp(refname, rte->ctename) != 0)
+				printalias = true;
 		}
+		if (printalias)
+			appendStringInfo(buf, " %s", quote_identifier(refname));
 
+		/* Print the column definitions or aliases, if needed */
 		if (rte->rtekind == RTE_FUNCTION)
 		{
 			if (rte->funccoltypes != NIL)
 			{
 				/* Function returning RECORD, reconstruct the columndefs */
-				if (!gavealias)
+				if (!printalias)
 					appendStringInfo(buf, " AS ");
 				get_from_clause_coldeflist(rte->eref->colnames,
 										   rte->funccoltypes,
diff --git a/src/test/regress/expected/with.out b/src/test/regress/expected/with.out
index 671f293b68d..b98ca630ee9 100644
--- a/src/test/regress/expected/with.out
+++ b/src/test/regress/expected/with.out
@@ -292,6 +292,30 @@ SELECT pg_get_viewdef('vsubdepartment'::regclass, true);
     FROM subdepartment;
 (1 row)
 
+-- Another reverse-listing example
+CREATE VIEW sums_1_100 AS
+WITH RECURSIVE t(n) AS (
+    VALUES (1)
+UNION ALL
+    SELECT n+1 FROM t WHERE n < 100
+)
+SELECT sum(n) FROM t;
+\d+ sums_1_100
+              View "public.sums_1_100"
+ Column |  Type  | Modifiers | Storage | Description 
+--------+--------+-----------+---------+-------------
+ sum    | bigint |           | plain   | 
+View definition:
+ WITH RECURSIVE t(n) AS (
+                 VALUES (1)
+        UNION ALL 
+                 SELECT t_1.n + 1
+                   FROM t t_1
+                  WHERE t_1.n < 100
+        )
+ SELECT sum(t.n) AS sum
+   FROM t;
+
 -- corner case in which sub-WITH gets initialized first
 with recursive q as (
       select * from department
diff --git a/src/test/regress/sql/with.sql b/src/test/regress/sql/with.sql
index 609f51b0c95..4ff852736bc 100644
--- a/src/test/regress/sql/with.sql
+++ b/src/test/regress/sql/with.sql
@@ -178,6 +178,17 @@ SELECT * FROM vsubdepartment ORDER BY name;
 SELECT pg_get_viewdef('vsubdepartment'::regclass);
 SELECT pg_get_viewdef('vsubdepartment'::regclass, true);
 
+-- Another reverse-listing example
+CREATE VIEW sums_1_100 AS
+WITH RECURSIVE t(n) AS (
+    VALUES (1)
+UNION ALL
+    SELECT n+1 FROM t WHERE n < 100
+)
+SELECT sum(n) FROM t;
+
+\d+ sums_1_100
+
 -- corner case in which sub-WITH gets initialized first
 with recursive q as (
       select * from department