patch 9.0.1959: Vim9: methods parameters and types are covariant
Problem: Vim9: methods parameters and types are covariant
Solution: Support contra-variant type check for object method arguments
(similar to Dart).
closes: #12965
closes: #13221
Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>
diff --git a/src/testdir/test_vim9_class.vim b/src/testdir/test_vim9_class.vim
index 9799a2f..856ee03 100644
--- a/src/testdir/test_vim9_class.vim
+++ b/src/testdir/test_vim9_class.vim
@@ -6318,4 +6318,80 @@
endfor
enddef
+" Test for checking the type of the arguments and the return value of a object
+" method in an extended class.
+def Test_extended_obj_method_type_check()
+ var lines =<< trim END
+ vim9script
+
+ class A
+ endclass
+ class B extends A
+ endclass
+ class C extends B
+ endclass
+
+ class Foo
+ def Doit(p: B): B
+ return B.new()
+ enddef
+ endclass
+
+ class Bar extends Foo
+ def Doit(p: A): C
+ return C.new()
+ enddef
+ endclass
+ END
+ v9.CheckSourceSuccess(lines)
+
+ lines =<< trim END
+ vim9script
+
+ class A
+ endclass
+ class B extends A
+ endclass
+ class C extends B
+ endclass
+
+ class Foo
+ def Doit(p: B): B
+ return B.new()
+ enddef
+ endclass
+
+ class Bar extends Foo
+ def Doit(p: C): B
+ return B.new()
+ enddef
+ endclass
+ END
+ v9.CheckSourceFailure(lines, 'E1383: Method "Doit": type mismatch, expected func(object<B>): object<B> but got func(object<C>): object<B>', 20)
+
+ lines =<< trim END
+ vim9script
+
+ class A
+ endclass
+ class B extends A
+ endclass
+ class C extends B
+ endclass
+
+ class Foo
+ def Doit(p: B): B
+ return B.new()
+ enddef
+ endclass
+
+ class Bar extends Foo
+ def Doit(p: B): A
+ return A.new()
+ enddef
+ endclass
+ END
+ v9.CheckSourceFailure(lines, 'E1383: Method "Doit": type mismatch, expected func(object<B>): object<B> but got func(object<B>): object<A>', 20)
+enddef
+
" vim: ts=8 sw=2 sts=2 expandtab tw=80 fdm=marker