Fix the implicit-RTE code to be able to handle implicit RTEs for CTEs, as

well as regular tables.  Per discussion, this seems necessary to meet the
principle of least astonishment.

In passing, simplify the error messages in warnAutoRange().  Now that we
have parser error position info for these errors, it doesn't seem very
useful to word the error message differently depending on whether we are
inside a sub-select or not.

src/backend/parser/parse_clause.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_clause.c,v 1.180 2008/10/04 21:56:54 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_clause.c,v 1.181 2008/10/06 02:12:56 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -631,34 +631,15 @@ transformFromClauseItem(ParseState *pstate, Node *n,
 		RangeTblEntry *rte = NULL;
 		int			rtindex;
 
-		/*
-		 * If it is an unqualified name, it might be a reference to some
-		 * CTE visible in this or a parent query.
-		 */
+		/* if it is an unqualified name, it might be a CTE reference */
 		if (!rv->schemaname)
 		{
-			ParseState *ps;
+			CommonTableExpr *cte;
 			Index	levelsup;
 
-			for (ps = pstate, levelsup = 0;
-				 ps != NULL;
-				 ps = ps->parentParseState, levelsup++)
-			{
-				ListCell *lc;
-
-				foreach(lc, ps->p_ctenamespace)
-				{
-					CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
-
-					if (strcmp(rv->relname, cte->ctename) == 0)
-					{
-						rte = transformCTEReference(pstate, rv, cte, levelsup);
-						break;
-					}
-				}
-				if (rte)
-					break;
-			}
+			cte = scanNameSpaceForCTE(pstate, rv->relname, &levelsup);
+			if (cte)
+				rte = transformCTEReference(pstate, rv, cte, levelsup);
 		}
 
 		/* if not found as a CTE, must be a table reference */

src/backend/parser/parse_relation.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_relation.c,v 1.136 2008/10/04 21:56:54 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_relation.c,v 1.137 2008/10/06 02:12:56 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -182,6 +182,38 @@ scanNameSpaceForRelid(ParseState *pstate, Oid relid, int location)
 	return result;
 }
 
+/*
+ * Search the query's CTE namespace for a CTE matching the given unqualified
+ * refname.  Return the CTE (and its levelsup count) if a match, or NULL
+ * if no match.  We need not worry about multiple matches, since parse_cte.c
+ * rejects WITH lists containing duplicate CTE names.
+ */
+CommonTableExpr *
+scanNameSpaceForCTE(ParseState *pstate, const char *refname,
+					Index *ctelevelsup)
+{
+	Index	levelsup;
+
+	for (levelsup = 0;
+		 pstate != NULL;
+		 pstate = pstate->parentParseState, levelsup++)
+	{
+		ListCell *lc;
+
+		foreach(lc, pstate->p_ctenamespace)
+		{
+			CommonTableExpr *cte = (CommonTableExpr *) lfirst(lc);
+
+			if (strcmp(cte->ctename, refname) == 0)
+			{
+				*ctelevelsup = levelsup;
+				return cte;
+			}
+		}
+	}
+	return NULL;
+}
+
 /*
  * searchRangeTable
  *	  See if any RangeTblEntry could possibly match the RangeVar.
@@ -194,16 +226,32 @@ scanNameSpaceForRelid(ParseState *pstate, Oid relid, int location)
  * valid matches, but only one will be returned).  This must be used ONLY
  * as a heuristic in giving suitable error messages.  See warnAutoRange.
  *
- * Notice that we consider both matches on actual relation name and matches
- * on alias.
+ * Notice that we consider both matches on actual relation (or CTE) name
+ * and matches on alias.
  */
 static RangeTblEntry *
 searchRangeTable(ParseState *pstate, RangeVar *relation)
 {
-	Oid			relId = RangeVarGetRelid(relation, true);
-	char	   *refname = relation->relname;
+	const char *refname = relation->relname;
+	Oid			relId = InvalidOid;
+	CommonTableExpr *cte = NULL;
+	Index		ctelevelsup = 0;
+	Index		levelsup;
 
-	while (pstate != NULL)
+	/*
+	 * If it's an unqualified name, check for possible CTE matches.
+	 * A CTE hides any real relation matches.  If no CTE, look for
+	 * a matching relation.
+	 */
+	if (!relation->schemaname)
+		cte = scanNameSpaceForCTE(pstate, refname, &ctelevelsup);
+	if (!cte)
+		relId = RangeVarGetRelid(relation, true);
+
+	/* Now look for RTEs matching either the relation/CTE or the alias */
+	for (levelsup = 0;
+		 pstate != NULL;
+		 pstate = pstate->parentParseState, levelsup++)
 	{
 		ListCell   *l;
 
@@ -211,15 +259,18 @@ searchRangeTable(ParseState *pstate, RangeVar *relation)
 		{
 			RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
 
-			if (OidIsValid(relId) &&
-				rte->rtekind == RTE_RELATION &&
+			if (rte->rtekind == RTE_RELATION &&
+				OidIsValid(relId) &&
 				rte->relid == relId)
 				return rte;
+			if (rte->rtekind == RTE_CTE &&
+				cte != NULL &&
+				rte->ctelevelsup + levelsup == ctelevelsup &&
+				strcmp(rte->ctename, refname) == 0)
+				return rte;
 			if (strcmp(rte->eref->aliasname, refname) == 0)
 				return rte;
 		}
-
-		pstate = pstate->parentParseState;
 	}
 	return NULL;
 }
@@ -1293,18 +1344,27 @@ addRTEtoQuery(ParseState *pstate, RangeTblEntry *rte,
 RangeTblEntry *
 addImplicitRTE(ParseState *pstate, RangeVar *relation)
 {
+	CommonTableExpr *cte = NULL;
+	Index		levelsup = 0;
 	RangeTblEntry *rte;
 
 	/* issue warning or error as needed */
 	warnAutoRange(pstate, relation);
 
+	/* if it is an unqualified name, it might be a CTE reference */
+	if (!relation->schemaname)
+		cte = scanNameSpaceForCTE(pstate, relation->relname, &levelsup);
+
 	/*
 	 * Note that we set inFromCl true, so that the RTE will be listed
 	 * explicitly if the parsetree is ever decompiled by ruleutils.c. This
 	 * provides a migration path for views/rules that were originally written
 	 * with implicit-RTE syntax.
 	 */
-	rte = addRangeTableEntry(pstate, relation, NULL, false, true);
+	if (cte)
+		rte = addRangeTableEntryForCTE(pstate, cte, levelsup, NULL, true);
+	else
+		rte = addRangeTableEntry(pstate, relation, NULL, false, true);
 	/* Add to joinlist and relnamespace, but not varnamespace */
 	addRTEtoQuery(pstate, rte, true, true, false);
 
@@ -2194,8 +2254,8 @@ warnAutoRange(ParseState *pstate, RangeVar *relation)
 		if (rte)
 			ereport(ERROR,
 					(errcode(ERRCODE_UNDEFINED_TABLE),
-			errmsg("invalid reference to FROM-clause entry for table \"%s\"",
-				   relation->relname),
+					 errmsg("invalid reference to FROM-clause entry for table \"%s\"",
+							relation->relname),
 					 (badAlias ?
 			errhint("Perhaps you meant to reference the table alias \"%s\".",
 					badAlias) :
@@ -2205,11 +2265,8 @@ warnAutoRange(ParseState *pstate, RangeVar *relation)
 		else
 			ereport(ERROR,
 					(errcode(ERRCODE_UNDEFINED_TABLE),
-					 (pstate->parentParseState ?
-			 errmsg("missing FROM-clause entry in subquery for table \"%s\"",
-					relation->relname) :
-					  errmsg("missing FROM-clause entry for table \"%s\"",
-							 relation->relname)),
+					 errmsg("missing FROM-clause entry for table \"%s\"",
+							relation->relname),
 					 parser_errposition(pstate, relation->location)));
 	}
 	else
@@ -2217,11 +2274,8 @@ warnAutoRange(ParseState *pstate, RangeVar *relation)
 		/* just issue a warning */
 		ereport(NOTICE,
 				(errcode(ERRCODE_UNDEFINED_TABLE),
-				 (pstate->parentParseState ?
-				  errmsg("adding missing FROM-clause entry in subquery for table \"%s\"",
-						 relation->relname) :
-				  errmsg("adding missing FROM-clause entry for table \"%s\"",
-						 relation->relname)),
+				 errmsg("adding missing FROM-clause entry for table \"%s\"",
+						relation->relname),
 				 (badAlias ?
 			errhint("Perhaps you meant to reference the table alias \"%s\".",
 					badAlias) :

src/include/parser/parse_relation.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/parser/parse_relation.h,v 1.59 2008/10/04 21:56:55 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/parser/parse_relation.h,v 1.60 2008/10/06 02:12:56 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -23,6 +23,9 @@ extern RangeTblEntry *refnameRangeTblEntry(ParseState *pstate,
 					 const char *refname,
 					 int location,
 					 int *sublevels_up);
+extern CommonTableExpr *scanNameSpaceForCTE(ParseState *pstate,
+											const char *refname,
+											Index *ctelevelsup);
 extern void checkNameSpaceConflicts(ParseState *pstate, List *namespace1,
 						List *namespace2);
 extern int RTERangeTablePosn(ParseState *pstate,