Come to think of it, functions in FROM have the same syntactic restriction

as CREATE INDEX did, and can be fixed the same way, for another small
improvement in usability and reduction in grammar size.

src/backend/parser/gram.y

@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.476 2004/09/29 23:39:20 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.477 2004/09/30 00:24:20 tgl Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -5368,24 +5368,7 @@ relation_expr:
 		;
 
 
-func_table: func_name '(' ')'
-				{
-					FuncCall *n = makeNode(FuncCall);
-					n->funcname = $1;
-					n->args = NIL;
-					n->agg_star = FALSE;
-					n->agg_distinct = FALSE;
-					$$ = (Node *)n;
-				}
-			| func_name '(' expr_list ')'
-				{
-					FuncCall *n = makeNode(FuncCall);
-					n->funcname = $1;
-					n->args = $3;
-					n->agg_star = FALSE;
-					n->agg_distinct = FALSE;
-					$$ = (Node *)n;
-				}
+func_table: func_expr								{ $$ = $1; }
 		;
 
 
@@ -6978,6 +6961,16 @@ func_expr:	func_name '(' ')'
 					n->agg_distinct = FALSE;
 					$$ = (Node *)n;
 				}
+			| NULLIF '(' a_expr ',' a_expr ')'
+				{
+					$$ = (Node *) makeSimpleA_Expr(AEXPR_NULLIF, "=", $3, $5);
+				}
+			| COALESCE '(' expr_list ')'
+				{
+					CoalesceExpr *c = makeNode(CoalesceExpr);
+					c->args = $3;
+					$$ = (Node *)c;
+				}
 		;
 
 /*
@@ -7206,24 +7199,12 @@ in_expr:	select_with_parens
 			| '(' expr_list ')'						{ $$ = (Node *)$2; }
 		;
 
-/* Case clause
+/*
  * Define SQL92-style case clause.
- * Allow all four forms described in the standard:
  * - Full specification
  *	CASE WHEN a = b THEN c ... ELSE d END
  * - Implicit argument
  *	CASE a WHEN b THEN c ... ELSE d END
- * - Conditional NULL
- *	NULLIF(x,y)
- *	same as CASE WHEN x = y THEN NULL ELSE x END
- * - Conditional substitution from list, use first non-null argument
- *	COALESCE(a,b,...)
- * same as CASE WHEN a IS NOT NULL THEN a WHEN b IS NOT NULL THEN b ... END
- * - thomas 1998-11-09
- *
- * NULLIF and COALESCE have become first class nodes to
- * prevent double evaluation of arguments.
- * - Kris Jurka 2003-02-11
  */
 case_expr:	CASE case_arg when_clause_list case_default END_P
 				{
@@ -7234,16 +7215,6 @@ case_expr:	CASE case_arg when_clause_list case_default END_P
 					c->defresult = (Expr *) $4;
 					$$ = (Node *)c;
 				}
-			| NULLIF '(' a_expr ',' a_expr ')'
-				{
-					$$ = (Node *) makeSimpleA_Expr(AEXPR_NULLIF, "=", $3, $5);
-				}
-			| COALESCE '(' expr_list ')'
-				{
-					CoalesceExpr *c = makeNode(CoalesceExpr);
-					c->args = $3;
-					$$ = (Node *)c;
-				}
 		;
 
 when_clause_list:

src/backend/parser/parse_clause.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_clause.c,v 1.136 2004/08/29 05:06:44 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_clause.c,v 1.137 2004/09/30 00:24:21 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -497,12 +497,16 @@ transformRangeFunction(ParseState *pstate, RangeFunction *r)
 	RangeTblEntry *rte;
 	RangeTblRef *rtr;
 
-	/* Get function name for possible use as alias */
-	Assert(IsA(r->funccallnode, FuncCall));
-	funcname = strVal(llast(((FuncCall *) r->funccallnode)->funcname));
+	/*
+	 * Get function name for possible use as alias.  We use the same
+	 * transformation rules as for a SELECT output expression.  For a
+	 * FuncCall node, the result will be the function name, but it is
+	 * possible for the grammar to hand back other node types.
+	 */
+	funcname = FigureColname(r->funccallnode);
 
 	/*
-	 * Transform the raw FuncCall node.
+	 * Transform the raw expression.
 	 */
 	funcexpr = transformExpr(pstate, r->funccallnode);
 

src/backend/parser/parse_target.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_target.c,v 1.125 2004/08/29 05:06:44 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_target.c,v 1.126 2004/09/30 00:24:21 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -41,7 +41,6 @@ static Node *transformAssignmentIndirection(ParseState *pstate,
 static List *ExpandColumnRefStar(ParseState *pstate, ColumnRef *cref);
 static List *ExpandAllTables(ParseState *pstate);
 static List *ExpandIndirectionStar(ParseState *pstate, A_Indirection *ind);
-static char *FigureColname(Node *node);
 static int	FigureColnameInternal(Node *node, char **name);
 
 
@@ -893,7 +892,7 @@ ExpandIndirectionStar(ParseState *pstate, A_Indirection *ind)
  * Note that the argument is the *untransformed* parse tree for the target
  * item.  This is a shade easier to work with than the transformed tree.
  */
-static char *
+char *
 FigureColname(Node *node)
 {
 	char	   *name = NULL;

src/include/parser/parse_target.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2004, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/parser/parse_target.h,v 1.33 2004/08/29 04:13:09 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/parser/parse_target.h,v 1.34 2004/09/30 00:24:27 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -27,5 +27,6 @@ extern void updateTargetListEntry(ParseState *pstate, TargetEntry *tle,
 					  List *indirection);
 extern List *checkInsertTargets(ParseState *pstate, List *cols,
 				   List **attrnos);
+extern char *FigureColname(Node *node);
 
 #endif   /* PARSE_TARGET_H */