Allow CALL with polymorphic type arguments

In order to be able to resolve polymorphic types, we need to set fn_expr
before invoking the procedure.

src/backend/commands/functioncmds.c

@@ -2264,6 +2264,7 @@ ExecuteCallStmt(CallStmt *stmt, ParamListInfo params, bool atomic, DestReceiver
 	/* Initialize function call structure */
 	InvokeFunctionExecuteHook(fexpr->funcid);
 	fmgr_info(fexpr->funcid, &flinfo);
+	fmgr_info_set_expr((Node *) fexpr, &flinfo);
 	InitFunctionCallInfoData(fcinfo, &flinfo, nargs, fexpr->inputcollid, (Node *) callcontext, NULL);
 
 	/*

src/test/regress/expected/create_procedure.out

@@ -116,6 +116,13 @@ SELECT * FROM cp_test;
  100 | Hello
 (8 rows)
 
+-- polymorphic types
+CREATE PROCEDURE ptest6(a int, b anyelement)
+LANGUAGE SQL
+AS $$
+SELECT NULL::int;
+$$;
+CALL ptest6(1, 2);
 -- various error cases
 CALL version();  -- error: not a procedure
 ERROR:  version() is not a procedure

src/test/regress/sql/create_procedure.sql

@@ -84,6 +84,17 @@ CALL ptest5(b => 'Hello', a => 10);
 SELECT * FROM cp_test;
 
 
+-- polymorphic types
+
+CREATE PROCEDURE ptest6(a int, b anyelement)
+LANGUAGE SQL
+AS $$
+SELECT NULL::int;
+$$;
+
+CALL ptest6(1, 2);
+
+
 -- various error cases
 
 CALL version();  -- error: not a procedure