patch 9.0.1959: Vim9: methods parameters and types are covariant
Commit:
https://github.com/vim/vim/commit/f3b68d4759a040ed0c4844c279ea3c779b3863ff
Author: Yegappan Lakshmanan <[email protected]>
Date: Fri Sep 29 22:50:02 2023 +0200
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 <[email protected]>
Co-authored-by: Yegappan Lakshmanan <[email protected]>
diff --git a/runtime/doc/vim9class.txt b/runtime/doc/vim9class.txt
index 6b51e86b6..066025469 100644
--- a/runtime/doc/vim9class.txt
+++ b/runtime/doc/vim9class.txt
@@ -530,6 +530,10 @@ If the type of a variable is not explicitly specified in a
class, then it is
set to "any" during class definition. When an object is instantiated from the
class, then the type of the variable is set.
+The following reserved keyword names cannot be used as an object or class
+variable name: "super", "this", "true", "false", "null", "null_blob",
+"null_dict", "null_function", "null_list", "null_partial", "null_string",
+"null_channel" and "null_job".
Extending a class ~
*extends*
@@ -543,9 +547,11 @@ Object variables from the base class are all taken over by
the child class. It
is not possible to override them (unlike some other languages).
*E1356* *E1357* *E1358*
-Object methods of the base class can be overruled. The signature (arguments,
-argument types and return type) must be exactly the same. The method of the
-base class can be called by prefixing "super.".
+Object methods of the base class can be overruled. The number of arguments
+must be exactly the same. The method argument type can be a contra-variant
+type of the base class method argument type. The method return value type can
+be a covariant type of the base class method return value type. The method of
+the base class can be called by prefixing "super.".
*E1377*
The access level of a method (public or private) in a child class should be
diff --git a/src/proto/vim9class.pro b/src/proto/vim9class.pro
index 9edf35408..31e2be70f 100644
--- a/src/proto/vim9class.pro
+++ b/src/proto/vim9class.pro
@@ -29,5 +29,5 @@ int object_free_nonref(int copyID);
void method_not_found_msg(class_T *cl, vartype_T v_type, char_u *name, size_t
len);
void member_not_found_msg(class_T *cl, vartype_T v_type, char_u *name, size_t
len);
void f_instanceof(typval_T *argvars, typval_T *rettv);
-int class_instance_of(class_T *cl, class_T *other_cl);
+int class_instance_of(class_T *cl, class_T *other_cl, int covariance_check);
/* vim: set ft=c : */
diff --git a/src/structs.h b/src/structs.h
index 009f16ea0..d05ae872d 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -4798,14 +4798,19 @@ typedef enum {
WT_ARGUMENT,
WT_VARIABLE,
WT_MEMBER,
- WT_METHOD,
+ WT_METHOD, // object method
+ WT_METHOD_ARG, // object method argument type
+ WT_METHOD_RETURN // object method return type
} wherekind_T;
-// Struct used to pass to error messages about where the error happened.
+// Struct used to pass the location of a type check. Used in error messages to
+// indicate where the error happened. Also used for doing covariance type
+// check for object method return type and contra-variance type check for
+// object method arguments.
typedef struct {
char *wt_func_name; // function name or NULL
char wt_index; // argument or variable index, 0 means unknown
- wherekind_T wt_kind; // "variable" when TRUE, "argument"
otherwise
+ wherekind_T wt_kind; // type check location
} where_T;
#define WHERE_INIT {NULL, 0, WT_UNKNOWN}
diff --git a/src/testdir/test_vim9_class.vim b/src/testdir/test_vim9_class.vim
index 9799a2f51..856ee0310 100644
--- a/src/testdir/test_vim9_class.vim
+++ b/src/testdir/test_vim9_class.vim
@@ -6318,4 +6318,80 @@ def Test_reserved_varname()
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
diff --git a/src/version.c b/src/version.c
index 766333e0a..e625ea674 100644
--- a/src/version.c
+++ b/src/version.c
@@ -699,6 +699,8 @@ static char *(features[]) =
static int included_patches[] =
{ /* Add new patch number below this line */
+/**/
+ 1959,
/**/
1958,
/**/
diff --git a/src/vim9class.c b/src/vim9class.c
index 885ac0385..790c2c36f 100644
--- a/src/vim9class.c
+++ b/src/vim9class.c
@@ -2561,7 +2561,7 @@ inside_class(cctx_T *cctx_arg, class_T *cl)
{
for (cctx_T *cctx = cctx_arg; cctx != NULL; cctx = cctx->ctx_outer)
if (cctx->ctx_ufunc != NULL
- && class_instance_of(cctx->ctx_ufunc->uf_class, cl))
+ && class_instance_of(cctx->ctx_ufunc->uf_class, cl,
TRUE))
return TRUE;
return FALSE;
}
@@ -2871,29 +2871,39 @@ member_not_found_msg(class_T *cl, vartype_T v_type,
char_u *name, size_t len)
* interfaces matches the class "other_cl".
*/
int
-class_instance_of(class_T *cl, class_T *other_cl)
+class_instance_of(class_T *cl, class_T *other_cl, int covariance_check)
{
if (cl == other_cl)
return TRUE;
- // Recursively check the base classes.
- for (; cl != NULL; cl = cl->class_extends)
+ if (covariance_check)
{
- if (cl == other_cl)
- return TRUE;
- // Check the implemented interfaces and the super interfaces
- for (int i = cl->class_interface_count - 1; i >= 0; --i)
+ // Recursively check the base classes.
+ for (; cl != NULL; cl = cl->class_extends)
{
- class_T *intf = cl->class_interfaces_cl[i];
- while (intf != NULL)
+ if (cl == other_cl)
+ return TRUE;
+ // Check the implemented interfaces and the super interfaces
+ for (int i = cl->class_interface_count - 1; i >= 0; --i)
{
- if (intf == other_cl)
- return TRUE;
- // check the super interfaces
- intf = intf->class_extends;
+ class_T *intf = cl->class_interfaces_cl[i];
+ while (intf != NULL)
+ {
+ if (intf == other_cl)
+ return TRUE;
+ // check the super interfaces
+ intf = intf->class_extends;
+ }
}
}
}
+ else
+ {
+ // contra-variance
+ for (; other_cl != NULL; other_cl = other_cl->class_extends)
+ if (cl == other_cl)
+ return TRUE;
+ }
return FALSE;
}
@@ -2928,7 +2938,7 @@ f_instanceof(typval_T *argvars, typval_T *rettv)
}
if (class_instance_of(object_tv->vval.v_object->obj_class,
- li->li_tv.vval.v_class) == TRUE)
+ li->li_tv.vval.v_class, TRUE) == TRUE)
{
rettv->vval.v_number = VVAL_TRUE;
return;
@@ -2937,8 +2947,9 @@ f_instanceof(typval_T *argvars, typval_T *rettv)
}
else if (classinfo_tv->v_type == VAR_CLASS)
{
- rettv->vval.v_number =
class_instance_of(object_tv->vval.v_object->obj_class,
- classinfo_tv->vval.v_class);
+ rettv->vval.v_number = class_instance_of(
+ object_tv->vval.v_object->obj_class,
+ classinfo_tv->vval.v_class, TRUE);
}
}
diff --git a/src/vim9type.c b/src/vim9type.c
index 6ca4b292e..4b8064df1 100644
--- a/src/vim9type.c
+++ b/src/vim9type.c
@@ -759,6 +759,8 @@ type_mismatch_where(type_T *expected, type_T *actual,
where_T where)
where.wt_func_name, typename1, typename2);
break;
case WT_METHOD:
+ case WT_METHOD_ARG:
+ case WT_METHOD_RETURN:
semsg(_(e_method_str_type_mismatch_expected_str_but_got_str),
where.wt_func_name, typename1, typename2);
break;
@@ -869,8 +871,15 @@ check_type_maybe(
{
if (actual->tt_member != NULL
&& actual->tt_member != &t_unknown)
+ {
+ where_T func_where = where;
+
+ if (where.wt_kind == WT_METHOD)
+ func_where.wt_kind = WT_METHOD_RETURN;
ret = check_type_maybe(expected->tt_member,
- actual->tt_member, FALSE, where);
+ actual->tt_member, FALSE,
+ func_where);
+ }
else
ret = MAYBE;
}
@@ -887,14 +896,20 @@ check_type_maybe(
for (i = 0; i < expected->tt_argcount
&& i < actual->tt_argcount; ++i)
+ {
+ where_T func_where = where;
+ if (where.wt_kind == WT_METHOD)
+ func_where.wt_kind = WT_METHOD_ARG;
+
// Allow for using "any" argument type, lambda's have them.
if (actual->tt_args[i] != &t_any && check_type(
expected->tt_args[i], actual->tt_args[i], FALSE,
- where) == FAIL)
+ func_where) == FAIL)
{
ret = FAIL;
break;
}
+ }
}
if (ret == OK && expected->tt_argcount >= 0
&& actual->tt_argcount == -1)
@@ -910,7 +925,10 @@ check_type_maybe(
if (actual->tt_class == NULL)
return OK; // A null object matches
- if (class_instance_of(actual->tt_class, expected->tt_class) ==
FALSE)
+ // For object method arguments, do a contra-variance type check in
+ // an extended class. For all others, do a co-variance type check.
+ if (class_instance_of(actual->tt_class, expected->tt_class,
+ where.wt_kind != WT_METHOD_ARG) == FALSE)
ret = FAIL;
}
--
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