patch 8.2.0519: Vim9: return type not properly checked

Problem:    Vim9: return type not properly checked.
Solution:   Check type properly, also at runtime.

Author: brammool

src/testdir/test_vim9_func.vim

@@ -380,6 +380,10 @@ def FuncOneArgRetNumber(arg: number): number
   return arg
 enddef
 
+def FuncOneArgRetAny(arg: any): any
+  return arg
+enddef
+
 def Test_func_type()
   let Ref1: func()
   funcResult = 0
@@ -417,5 +421,20 @@ def Test_func_type_fails()
   CheckDefFailure(['let Ref1: func()', 'Ref1 = FuncOneArgRetNumber'], 'E1013: type mismatch, expected func() but got func(number): number')
 enddef
 
+def Test_func_return_type()
+  let nr: number
+  nr = FuncNoArgRetNumber()
+  assert_equal(1234, nr)
+
+  nr = FuncOneArgRetAny(122)
+  assert_equal(122, nr)
+
+  let str: string
+  str = FuncOneArgRetAny('yes')
+  assert_equal('yes', str)
+
+  CheckDefFailure(['let str: string', 'str = FuncNoArgRetNumber()'], 'E1013: type mismatch, expected string but got number')
+enddef
+
 
 " vim: ts=8 sw=2 sts=2 expandtab tw=80 fdm=marker

src/version.c

@@ -738,6 +738,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    519,
 /**/
     518,
 /**/

src/vim9compile.c

@@ -2432,7 +2432,7 @@ check_type(type_T *expected, type_T *actual, int give_msg)
 	if (ret == FAIL && give_msg)
 	    type_mismatch(expected, actual);
     }
-    return OK;
+    return ret;
 }
 
 /*
@@ -2444,7 +2444,7 @@ check_type(type_T *expected, type_T *actual, int give_msg)
     static int
 need_type(type_T *actual, type_T *expected, int offset, cctx_T *cctx)
 {
-    if (check_type(expected, actual, FALSE))
+    if (check_type(expected, actual, FALSE) == OK)
 	return OK;
     if (actual->tt_type != VAR_ANY && actual->tt_type != VAR_UNKNOWN)
     {
@@ -4069,7 +4069,7 @@ compile_assignment(char_u *arg, exarg_T *eap, cmdidx_T cmdidx, cctx_T *cctx)
 			lvar->lv_type = stacktype;
 		}
 	    }
-	    else if (check_type(lvar->lv_type, stacktype, TRUE) == FAIL)
+	    else if (need_type(stacktype, lvar->lv_type, -1, cctx) == FAIL)
 		goto theend;
 	}
 	else if (*p != '=' && check_type(type, stacktype, TRUE) == FAIL)