Change PROCEDURE to FUNCTION in CREATE OPERATOR syntax

Since procedures are now a different thing from functions, change the
CREATE OPERATOR syntax to use FUNCTION in the clause that specifies the
function.  PROCEDURE is still accepted for compatibility.
Reported-by: Peter Geoghegan <pg@bowt.ie>
Reviewed-by: Jonathan S. Katz <jonathan.katz@excoventures.com>

doc/src/sgml/extend.sgml

@@ -1015,7 +1015,7 @@ CREATE TYPE pair AS ( k text, v text );
 CREATE OR REPLACE FUNCTION pair(text, text)
 RETURNS pair LANGUAGE SQL AS 'SELECT ROW($1, $2)::@extschema@.pair;';
 
-CREATE OPERATOR ~> (LEFTARG = text, RIGHTARG = text, PROCEDURE = pair);
+CREATE OPERATOR ~> (LEFTARG = text, RIGHTARG = text, FUNCTION = pair);
 
 -- "SET search_path" is easy to get right, but qualified names perform better.
 CREATE OR REPLACE FUNCTION lower(pair)

doc/src/sgml/ref/create_operator.sgml

@@ -22,7 +22,7 @@ PostgreSQL documentation
  <refsynopsisdiv>
 <synopsis>
 CREATE OPERATOR <replaceable>name</replaceable> (
-    PROCEDURE = <replaceable class="parameter">function_name</replaceable>
+    {FUNCTION|PROCEDURE} = <replaceable class="parameter">function_name</replaceable>
     [, LEFTARG = <replaceable class="parameter">left_type</replaceable> ] [, RIGHTARG = <replaceable class="parameter">right_type</replaceable> ]
     [, COMMUTATOR = <replaceable class="parameter">com_op</replaceable> ] [, NEGATOR = <replaceable class="parameter">neg_op</replaceable> ]
     [, RESTRICT = <replaceable class="parameter">res_proc</replaceable> ] [, JOIN = <replaceable class="parameter">join_proc</replaceable> ]
@@ -99,6 +99,14 @@ CREATE OPERATOR <replaceable>name</replaceable> (
    of arguments (either one or two) of the indicated types.
   </para>
 
+  <para>
+   In the syntax of <literal>CREATE OPERATOR</literal>, the keywords
+   <literal>FUNCTION</literal> and <literal>PROCEDURE</literal> are
+   equivalent, but the referenced function must in any case be a function, not
+   a procedure.  The use of the keyword <literal>PROCEDURE</literal> here is
+   historical and deprecated.
+  </para>
+
   <para>
    The other clauses specify optional operator optimization clauses.
    Their meaning is detailed in <xref linkend="xoper-optimization"/>.
@@ -264,7 +272,7 @@ COMMUTATOR = OPERATOR(myschema.===) ,
 CREATE OPERATOR === (
     LEFTARG = box,
     RIGHTARG = box,
-    PROCEDURE = area_equal_function,
+    FUNCTION = area_equal_function,
     COMMUTATOR = ===,
     NEGATOR = !==,
     RESTRICT = area_restriction_function,

doc/src/sgml/xoper.sgml

@@ -44,7 +44,7 @@ CREATE FUNCTION complex_add(complex, complex)
 CREATE OPERATOR + (
     leftarg = complex,
     rightarg = complex,
-    procedure = complex_add,
+    function = complex_add,
     commutator = +
 );
 </programlisting>
@@ -66,7 +66,7 @@ SELECT (a + b) AS c FROM test_complex;
   <para>
    We've shown how to create a binary operator here.  To create unary
    operators, just omit one of <literal>leftarg</literal> (for left unary) or
-   <literal>rightarg</literal> (for right unary).  The <literal>procedure</literal>
+   <literal>rightarg</literal> (for right unary).  The <literal>function</literal>
    clause and the argument clauses are the only required items in
    <command>CREATE OPERATOR</command>.  The <literal>commutator</literal>
    clause shown in the example is an optional hint to the query

src/backend/commands/operatorcmds.c

@@ -21,7 +21,7 @@
  * NOTES
  *	  These things must be defined and committed in the following order:
  *		"create function":
- *				input/output, recv/send procedures
+ *				input/output, recv/send functions
  *		"create type":
  *				type
  *		"create operator":
@@ -79,8 +79,8 @@ DefineOperator(List *names, List *parameters)
 	Oid			rettype;
 	List	   *commutatorName = NIL;	/* optional commutator operator name */
 	List	   *negatorName = NIL;	/* optional negator operator name */
-	List	   *restrictionName = NIL;	/* optional restrict. sel. procedure */
-	List	   *joinName = NIL; /* optional join sel. procedure */
+	List	   *restrictionName = NIL;	/* optional restrict. sel. function */
+	List	   *joinName = NIL; /* optional join sel. function */
 	Oid			functionOid;	/* functions converted to OID */
 	Oid			restrictionOid;
 	Oid			joinOid;
@@ -120,6 +120,9 @@ DefineOperator(List *names, List *parameters)
 						(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
 						 errmsg("SETOF type not allowed for operator argument")));
 		}
+		/* "function" and "procedure" are equivalent here */
+		else if (strcmp(defel->defname, "function") == 0)
+			functionName = defGetQualifiedName(defel);
 		else if (strcmp(defel->defname, "procedure") == 0)
 			functionName = defGetQualifiedName(defel);
 		else if (strcmp(defel->defname, "commutator") == 0)
@@ -159,7 +162,7 @@ DefineOperator(List *names, List *parameters)
 	if (functionName == NIL)
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
-				 errmsg("operator procedure must be specified")));
+				 errmsg("operator function must be specified")));
 
 	/* Transform type names to type OIDs */
 	if (typeName1)
@@ -245,8 +248,8 @@ DefineOperator(List *names, List *parameters)
 					   functionOid, /* function for operator */
 					   commutatorName,	/* optional commutator operator name */
 					   negatorName, /* optional negator operator name */
-					   restrictionOid,	/* optional restrict. sel. procedure */
-					   joinOid, /* optional join sel. procedure name */
+					   restrictionOid,	/* optional restrict. sel. function */
+					   joinOid, /* optional join sel. function name */
 					   canMerge,	/* operator merges */
 					   canHash);	/* operator hashes */
 }
@@ -393,10 +396,10 @@ AlterOperator(AlterOperatorStmt *stmt)
 	Datum		values[Natts_pg_operator];
 	bool		nulls[Natts_pg_operator];
 	bool		replaces[Natts_pg_operator];
-	List	   *restrictionName = NIL;	/* optional restrict. sel. procedure */
+	List	   *restrictionName = NIL;	/* optional restrict. sel. function */
 	bool		updateRestriction = false;
 	Oid			restrictionOid;
-	List	   *joinName = NIL; /* optional join sel. procedure */
+	List	   *joinName = NIL; /* optional join sel. function */
 	bool		updateJoin = false;
 	Oid			joinOid;
 
@@ -436,6 +439,7 @@ AlterOperator(AlterOperatorStmt *stmt)
 		 */
 		else if (strcmp(defel->defname, "leftarg") == 0 ||
 				 strcmp(defel->defname, "rightarg") == 0 ||
+				 strcmp(defel->defname, "function") == 0 ||
 				 strcmp(defel->defname, "procedure") == 0 ||
 				 strcmp(defel->defname, "commutator") == 0 ||
 				 strcmp(defel->defname, "negator") == 0 ||

src/bin/pg_dump/pg_dump.c

@@ -12415,7 +12415,7 @@ dumpOpr(Archive *fout, OprInfo *oprinfo)
 	oprregproc = convertRegProcReference(fout, oprcode);
 	if (oprregproc)
 	{
-		appendPQExpBuffer(details, "    PROCEDURE = %s", oprregproc);
+		appendPQExpBuffer(details, "    FUNCTION = %s", oprregproc);
 		free(oprregproc);
 	}
 

src/test/regress/expected/create_operator.out

@@ -4,7 +4,7 @@
 CREATE OPERATOR ## (
    leftarg = path,
    rightarg = path,
-   procedure = path_inter,
+   function = path_inter,
    commutator = ##
 );
 CREATE OPERATOR <% (
@@ -107,7 +107,7 @@ ERROR:  at least one of leftarg or rightarg must be specified
 CREATE OPERATOR #@%# (
    leftarg = int8
 );
-ERROR:  operator procedure must be specified
+ERROR:  operator function must be specified
 -- Should fail. CREATE OPERATOR requires USAGE on TYPE
 BEGIN TRANSACTION;
 CREATE ROLE regress_rol_op3;
@@ -202,4 +202,4 @@ WARNING:  operator attribute "Restrict" not recognized
 WARNING:  operator attribute "Join" not recognized
 WARNING:  operator attribute "Hashes" not recognized
 WARNING:  operator attribute "Merges" not recognized
-ERROR:  operator procedure must be specified
+ERROR:  operator function must be specified

src/test/regress/sql/create_operator.sql

@@ -5,7 +5,7 @@
 CREATE OPERATOR ## (
    leftarg = path,
    rightarg = path,
-   procedure = path_inter,
+   function = path_inter,
    commutator = ##
 );