#3057. Update promotion via assignment tests

TypeSystem/flow-analysis/promotion_via_assignment_A01_t01.dart

@@ -2,15 +2,14 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-/// @assertion We say that a variable x is promotable via assignment of an
-/// expression of type T given variable model VM if
-///
-///  VM = VariableModel(declared, promoted, tested, assigned, unassigned,
-///  captured)
-///  and captured is false
-///  and S is the current type of x in VM
-///  and T <: S and not S <: T
-///  and T is a type of interest for x in tested
+/// @assertion We say that a variable `x` is promotable via assignment of an
+/// expression of type `T` given variable model `VM` if
+/// - `VM = VariableModel(declared, promoted, tested, assigned, unassigned,
+///     captured)`
+/// - and captured is false
+/// - and `S` is the current type of `x` in `VM`
+/// - and `T <: S` and not `S <: T`
+/// - and `T` is a type of interest for `x` in `tested`
 ///
 /// @description Checks that a variable is promotable to the type `T` if all
 /// requirements above are met.

TypeSystem/flow-analysis/promotion_via_assignment_A02_t01.dart

@@ -2,15 +2,14 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-/// @assertion We say that a variable x is promotable via assignment of an
-/// expression of type T given variable model VM if
-///
-///  VM = VariableModel(declared, promoted, tested, assigned, unassigned,
-///  captured)
-///  and captured is false
-///  and S is the current type of x in VM
-///  and T <: S and not S <: T
-///  and T is a type of interest for x in tested
+/// @assertion We say that a variable `x` is promotable via assignment of an
+/// expression of type `T` given variable model `VM` if
+/// - `VM = VariableModel(declared, promoted, tested, assigned, unassigned,
+///     captured)`
+/// - and captured is false
+/// - and `S` is the current type of `x` in `VM`
+/// - and `T <: S` and not `S <: T`
+/// - and `T` is a type of interest for `x` in `tested`
 ///
 /// @description Checks that if `captured` is `true` then promotion via
 /// assignment is not performed
@@ -21,14 +20,11 @@ class T extends S {
   int foo() => 42;
 }
 
-Function? f;
-
 main() {
   S x = new S();
   void bar(var v) {
     x = v;
   }
-  f = bar;
   if (x is T) {} // make `T` a type of interest
   x = new T();
   x.foo();

TypeSystem/flow-analysis/promotion_via_assignment_A03_t01.dart

@@ -2,33 +2,40 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-/// @assertion We say that a variable x is promotable via assignment of an
-/// expression of type T given variable model VM if
-///
-///  VM = VariableModel(declared, promoted, tested, assigned, unassigned,
-///  captured)
-///  and captured is false
-///  and S is the current type of x in VM
-///  and T <: S and not S <: T
-///  and T is a type of interest for x in tested
+/// @assertion We say that a variable `x` is promotable via assignment of an
+/// expression of type `T` given variable model `VM` if
+/// - `VM = VariableModel(declared, promoted, tested, assigned, unassigned,
+///     captured)`
+/// - and captured is false
+/// - and `S` is the current type of `x` in `VM`
+/// - and `T <: S` and not `S <: T`
+/// - and `T` is a type of interest for `x` in `tested`
 ///
 /// @description Checks that if `T <: S` and `S <: T` then promotion via
-/// assignment is not performed
+/// assignment is not performed.
 /// @author sgrekhov@unipro.ru
 
-import '../../Utils/expect.dart';
+import 'dart:async';
+import '../../Utils/static_type_helper.dart';
+
+test1(FutureOr<Object> v) {
+  if (v is Object) {} // ignore: unnecessary_type_check
+  v = Object();
+  // `Object` <: `FutureOr<Object>` and `FutureOr<Object>` <: `Object`.
+  // Therefore `v` is not promoted to `Object`.
+  v.expectStaticType<Exactly<FutureOr<Object>>>();
+}
 
-class S {}
-class T extends S {
-  int foo() => 42;
+test2(FutureOr<Object?> v) {
+  if (v is Object?) {} // ignore: unnecessary_type_check
+  v = 1 > 2 ? null: Object();
+  // `Object?` <: `FutureOr<Object?>` and `FutureOr<Object?>` <: `Object?`.
+  // Therefore `v` is not promoted to `Object?`.
+  v.expectStaticType<Exactly<FutureOr<Object?>>>();
 }
 
 main() {
-  dynamic x = new S();
-  if (x is T) {} // make `T` a type of interest
-  x = new T();
-  x.foo();
-  Expect.throws(() {
-    x.bar();
-  }, (e) => e is NoSuchMethodError);
+  test1(Object());
+  test2(Object());
+  test2(null);
 }

TypeSystem/flow-analysis/promotion_via_assignment_A03_t02.dart

@@ -0,0 +1,32 @@
+// Copyright (c) 2025, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// @assertion We say that a variable `x` is promotable via assignment of an
+/// expression of type `T` given variable model `VM` if
+/// - `VM = VariableModel(declared, promoted, tested, assigned, unassigned,
+///     captured)`
+/// - and captured is false
+/// - and `S` is the current type of `x` in `VM`
+/// - and `T <: S` and not `S <: T`
+/// - and `T` is a type of interest for `x` in `tested`
+///
+/// @description Checks that if `T` is not subtype of `S` then promotion via
+/// assignment cannot be performed.
+/// @author sgrekhov22@gmail.com
+/// @issue 60646
+
+main() {
+  Object? s = "Some string";
+  s as String;      // `s` promoted to `String`
+  if (s is int) {}  // Make `int` a type of interest for `s`.
+  s = 42;           // `s` demoted to `Object`
+  s.isEven;
+//  ^^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  s.substring(0);
+//  ^^^^^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+}

TypeSystem/flow-analysis/promotion_via_assignment_A04_t01.dart

@@ -2,15 +2,14 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-/// @assertion We say that a variable x is promotable via assignment of an
-/// expression of type T given variable model VM if
-///
-///  VM = VariableModel(declared, promoted, tested, assigned, unassigned,
-///  captured)
-///  and captured is false
-///  and S is the current type of x in VM
-///  and T <: S and not S <: T
-///  and T is a type of interest for x in tested
+/// @assertion We say that a variable `x` is promotable via assignment of an
+/// expression of type `T` given variable model `VM` if
+/// - `VM = VariableModel(declared, promoted, tested, assigned, unassigned,
+///     captured)`
+/// - and captured is false
+/// - and `S` is the current type of `x` in `VM`
+/// - and `T <: S` and not `S <: T`
+/// - and `T` is a type of interest for `x` in `tested`
 ///
 /// @description Checks that if `T` is not a type of interest for `x` in
 /// `tested` then promotion via assignment is not performed.