PL/pgSQL: Simplify RETURN checking for procedures

Check at compile time that RETURN in a procedure does not specify a
parameter, rather than at run time.

src/pl/plpgsql/src/expected/plpgsql_call.out

@@ -17,9 +17,9 @@ BEGIN
     RETURN 5;
 END;
 $$;
-CALL test_proc2();
-ERROR:  cannot return a value from a procedure
-CONTEXT:  PL/pgSQL function test_proc2() while casting return value to function's return type
+ERROR:  RETURN cannot have a parameter in a procedure
+LINE 5:     RETURN 5;
+                   ^
 CREATE TABLE test1 (a int);
 CREATE PROCEDURE test_proc3(x int)
 LANGUAGE plpgsql
@@ -54,7 +54,6 @@ SELECT * FROM test1;
 (2 rows)
 
 DROP PROCEDURE test_proc1;
-DROP PROCEDURE test_proc2;
 DROP PROCEDURE test_proc3;
 DROP PROCEDURE test_proc4;
 DROP TABLE test1;

src/pl/plpgsql/src/pl_exec.c

@@ -617,11 +617,6 @@ plpgsql_exec_function(PLpgSQL_function *func, FunctionCallInfo fcinfo,
 	}
 	else if (!estate.retisnull)
 	{
-		if (func->fn_prokind == PROKIND_PROCEDURE)
-			ereport(ERROR,
-					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-					 errmsg("cannot return a value from a procedure")));
-
 		/*
 		 * Cast result value to function's declared result type, and copy it
 		 * out to the upper executor memory context.  We must treat tuple

src/pl/plpgsql/src/pl_gram.y

@@ -3138,14 +3138,21 @@ make_return_stmt(int location)
 					 parser_errposition(yylloc)));
 		new->retvarno = plpgsql_curr_compile->out_param_varno;
 	}
-	else if (plpgsql_curr_compile->fn_rettype == VOIDOID &&
-			 plpgsql_curr_compile->fn_prokind != PROKIND_PROCEDURE)
+	else if (plpgsql_curr_compile->fn_rettype == VOIDOID)
 	{
 		if (yylex() != ';')
-			ereport(ERROR,
-					(errcode(ERRCODE_DATATYPE_MISMATCH),
-					 errmsg("RETURN cannot have a parameter in function returning void"),
-					 parser_errposition(yylloc)));
+		{
+			if (plpgsql_curr_compile->fn_prokind == PROKIND_PROCEDURE)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("RETURN cannot have a parameter in a procedure"),
+						 parser_errposition(yylloc)));
+			else
+				ereport(ERROR,
+						(errcode(ERRCODE_DATATYPE_MISMATCH),
+						 errmsg("RETURN cannot have a parameter in function returning void"),
+						 parser_errposition(yylloc)));
+		}
 	}
 	else
 	{

src/pl/plpgsql/src/sql/plpgsql_call.sql

@@ -22,8 +22,6 @@ BEGIN
 END;
 $$;
 
-CALL test_proc2();
-
 
 CREATE TABLE test1 (a int);
 
@@ -58,7 +56,6 @@ SELECT * FROM test1;
 
 
 DROP PROCEDURE test_proc1;
-DROP PROCEDURE test_proc2;
 DROP PROCEDURE test_proc3;
 DROP PROCEDURE test_proc4;