fix #26120, sideways casts no longer supported

pkg/analyzer/test/src/task/strong/checker_test.dart

 // Copyright (c) 2015, 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.
 
 library analyzer.test.src.task.strong.checker_test;
 
 import '../../../reflective_tests.dart';
 import 'strong_test_helper.dart';
 
 void main() {
@@ skipping 789 matching lines @@
     Top f;
     f = top;
     f = left;
     f = right;
     f = bot;
   }
   {
     Left f;
     f = /*error:STATIC_TYPE_ERROR*/top;
     f = left;
-    f = /*error:STATIC_TYPE_ERROR*/right;
+    f = /*error:INVALID_ASSIGNMENT*/right;
     f = bot;
   }
   {
     Right f;
     f = /*error:STATIC_TYPE_ERROR*/top;
-    f = /*error:STATIC_TYPE_ERROR*/left;
+    f = /*error:INVALID_ASSIGNMENT*/left;
     f = right;
     f = bot;
   }
   {
     Bot f;
     f = /*error:STATIC_TYPE_ERROR*/top;
     f = /*error:STATIC_TYPE_ERROR*/left;
     f = /*error:STATIC_TYPE_ERROR*/right;
     f = bot;
   }
@@ skipping 19 matching lines @@
     Top f;
     f = top;
     f = left;
     f = right;
     f = bot;
   }
   {
     Left f;
     f = /*warning:DOWN_CAST_COMPOSITE*/top;
     f = left;
-    f = /*warning:DOWN_CAST_COMPOSITE*/right;
+    f = /*error:INVALID_ASSIGNMENT*/right;
     f = bot;
   }
   {
     Right f;
     f = /*warning:DOWN_CAST_COMPOSITE*/top;
-    f = /*warning:DOWN_CAST_COMPOSITE*/left;
+    f = /*error:INVALID_ASSIGNMENT*/left;
     f = right;
     f = bot;
   }
   {
     Bottom f;
     f = /*warning:DOWN_CAST_COMPOSITE*/top;
     f = /*warning:DOWN_CAST_COMPOSITE*/left;
     f = /*warning:DOWN_CAST_COMPOSITE*/right;
     f = bot;
   }
@@ skipping 60 matching lines @@
         botA,
         botTop
                       );
   }
   {
     ATop f;
     f = topA;
     f = topTop;
     f = aa;
     f = aTop;
-    f = /*warning:DOWN_CAST_COMPOSITE should be error:STATIC_TYPE_ERROR*/botA;
+    f = /*error:INVALID_ASSIGNMENT*/botA;
     f = /*warning:DOWN_CAST_COMPOSITE*/botTop;
     apply/*<ATop>*/(
         topA,
         topTop,
         aa,
         aTop,
-        /*warning:DOWN_CAST_COMPOSITE should be error:STATIC_TYPE_ERROR*/botA,
+        /*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/botA,
         /*warning:DOWN_CAST_COMPOSITE*/botTop
                     );
     apply/*<ATop>*/(
         (dynamic x) => new A(),
         (dynamic x) => (x as Object),
         (A x) => x,
         (A x) => null,
-        /*warning:DOWN_CAST_COMPOSITE should be error:STATIC_TYPE_ERROR*/botA,
+        /*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/botA,
         /*warning:DOWN_CAST_COMPOSITE*/botTop
                     );
   }
   {
     BotA f;
     f = topA;
-    f = /*error:STATIC_TYPE_ERROR*/topTop;
+    f = /*error:INVALID_ASSIGNMENT*/topTop;
     f = aa;
-    f = /*error:STATIC_TYPE_ERROR*/aTop;
+    f = /*error:INVALID_ASSIGNMENT*/aTop;
     f = botA;
     f = /*warning:DOWN_CAST_COMPOSITE*/botTop;
     apply/*<BotA>*/(
         topA,
-        /*error:STATIC_TYPE_ERROR*/topTop,
+        /*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/topTop,
         aa,
-        /*error:STATIC_TYPE_ERROR*/aTop,
+        /*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/aTop,
         botA,
         /*warning:DOWN_CAST_COMPOSITE*/botTop
                     );
     apply/*<BotA>*/(
         (dynamic x) => new A(),
-        /*error:STATIC_TYPE_ERROR*/(dynamic x) => (x as Object),
+        /*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/(dynamic x) => (x as Object),
         (A x) => x,
-        /*error:STATIC_TYPE_ERROR*/(A x) => (x as Object),
+        /*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/(A x) => (x as Object),
         botA,
         /*warning:DOWN_CAST_COMPOSITE*/botTop
                     );
   }
   {
     AA f;
     f = topA;
-    f = /*error:STATIC_TYPE_ERROR*/topTop;
+    f = /*error:INVALID_ASSIGNMENT*/topTop;
     f = aa;
     f = /*error:STATIC_TYPE_ERROR*/aTop; // known function
     f = /*warning:DOWN_CAST_COMPOSITE*/botA;
     f = /*warning:DOWN_CAST_COMPOSITE*/botTop;
     apply/*<AA>*/(
         topA,
-        /*error:STATIC_TYPE_ERROR*/topTop,
+        /*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/topTop,
         aa,
         /*error:STATIC_TYPE_ERROR*/aTop, // known function
         /*warning:DOWN_CAST_COMPOSITE*/botA,
         /*warning:DOWN_CAST_COMPOSITE*/botTop
                   );
     apply/*<AA>*/(
         (dynamic x) => new A(),
-        /*error:STATIC_TYPE_ERROR*/(dynamic x) => (x as Object),
+        /*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/(dynamic x) => (x as Object),
         (A x) => x,
         /*error:STATIC_TYPE_ERROR*/(A x) => (x as Object), // known function
         /*warning:DOWN_CAST_COMPOSITE*/botA,
         /*warning:DOWN_CAST_COMPOSITE*/botTop
                   );
   }
   {
     TopTop f;
     f = topA;
     f = topTop;
-    f = /*error:STATIC_TYPE_ERROR*/aa;
+    f = /*error:INVALID_ASSIGNMENT*/aa;
     f = /*error:STATIC_TYPE_ERROR*/aTop; // known function
-    f = /*warning:DOWN_CAST_COMPOSITE should be error:STATIC_TYPE_ERROR*/botA;
+    f = /*error:INVALID_ASSIGNMENT*/botA;
     f = /*warning:DOWN_CAST_COMPOSITE*/botTop;
     apply/*<TopTop>*/(
         topA,
         topTop,
-        /*error:STATIC_TYPE_ERROR*/aa,
+        /*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/aa,
         /*error:STATIC_TYPE_ERROR*/aTop, // known function
-        /*warning:DOWN_CAST_COMPOSITE should be error:STATIC_TYPE_ERROR*/botA,
+        /*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/botA,
         /*warning:DOWN_CAST_COMPOSITE*/botTop
                       );
     apply/*<TopTop>*/(
         (dynamic x) => new A(),
         (dynamic x) => (x as Object),
-        /*error:STATIC_TYPE_ERROR*/(A x) => x,
+        /*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/(A x) => x,
         /*error:STATIC_TYPE_ERROR*/(A x) => (x as Object), // known function
-        /*warning:DOWN_CAST_COMPOSITE should be error:STATIC_TYPE_ERROR*/botA,
+        /*error:ARGUMENT_TYPE_NOT_ASSIGNABLE*/botA,
         /*warning:DOWN_CAST_COMPOSITE*/botTop
                       );
   }
   {
     TopA f;
     f = topA;
     f = /*error:STATIC_TYPE_ERROR*/topTop; // known function
     f = /*error:STATIC_TYPE_ERROR*/aa; // known function
     f = /*error:STATIC_TYPE_ERROR*/aTop; // known function
     f = /*warning:DOWN_CAST_COMPOSITE*/botA;
@@ skipping 90 matching lines @@
 
 void main() {
   {
     Function2<B, A> f;
     f = top;
     f = left;
     f = right;
     f = bot;
   }
   {
-    Function2<B, B> f;
+    Function2<B, B> f; // left
     f = /*error:STATIC_TYPE_ERROR*/top;
     f = left;
-    f = /*error:STATIC_TYPE_ERROR*/right;
+    f = /*error:INVALID_ASSIGNMENT*/right;
     f = bot;
   }
   {
-    Function2<A, A> f;
+    Function2<A, A> f; // right
     f = /*error:STATIC_TYPE_ERROR*/top;
-    f = /*error:STATIC_TYPE_ERROR*/left;
+    f = /*error:INVALID_ASSIGNMENT*/left;
     f = right;
     f = bot;
   }
   {
     Function2<A, B> f;
     f = /*error:STATIC_TYPE_ERROR*/top;
     f = /*error:STATIC_TYPE_ERROR*/left;
     f = /*error:STATIC_TYPE_ERROR*/right;
     f = bot;
   }
@@ skipping 15 matching lines @@
     Function2<A, A> right;
     Function2<A, B> bot;
 
     top = right;
     top = bot;
     top = top;
     top = left;
 
     left = /*warning:DOWN_CAST_COMPOSITE*/top;
     left = left;
-    left = /*warning:DOWN_CAST_COMPOSITE*/right; // Should we reject this?
+    left = /*error:INVALID_ASSIGNMENT*/right;
     left = bot;
 
-    right = /*warning:DOWN_CAST_COMPOSITE*/top;
-    right = /*warning:DOWN_CAST_COMPOSITE*/left; // Should we reject this?
-    right = right;
+    right = /*info:INVALID_ASSIGNMENT,warning:DOWN_CAST_COMPOSITE*/top;
+    right = /*error:INVALID_ASSIGNMENT*/left;
+    right = /*info:INVALID_ASSIGNMENT*/right;

[Jennifer Messerly, 2016/08/10 22:24:07]

note this hint. Analyzer seems to track which type was last assigned to the
variable, so it flags this. Anyway it would be easy to disable these hints if we
wanted to, but it seems harmless enough, since it only shows up in this example
which is intentionally doing bad things :). It is using our type system for the
hint.

[Brian Wilkerson, 2016/08/10 22:56:02]

The hint is a result of type propagation, which will be removed fairly
soon(ish).

[Jennifer Messerly, 2016/08/11 00:51:19]

oh nice!

     right = bot;
 
     bot = /*warning:DOWN_CAST_COMPOSITE*/top;
     bot = /*warning:DOWN_CAST_COMPOSITE*/left;
     bot = /*warning:DOWN_CAST_COMPOSITE*/right;
     bot = bot;
   }
 }
 ''');
   }
@@ skipping 19 matching lines @@
     Function2<AToB, BToA> f; // Top
     f = top;
     f = left;
     f = right;
     f = bot;
   }
   {
     Function2<AToB, AToB> f; // Left
     f = /*error:STATIC_TYPE_ERROR*/top;
     f = left;
-    f = /*error:STATIC_TYPE_ERROR*/right;
+    f = /*error:INVALID_ASSIGNMENT*/right;
     f = bot;
   }
   {
     Function2<BToA, BToA> f; // Right
     f = /*error:STATIC_TYPE_ERROR*/top;
-    f = /*error:STATIC_TYPE_ERROR*/left;
+    f = /*error:INVALID_ASSIGNMENT*/left;
     f = right;
     f = bot;
   }
   {
     Function2<BToA, AToB> f; // Bot
     f = bot;
     f = /*error:STATIC_TYPE_ERROR*/left;
     f = /*error:STATIC_TYPE_ERROR*/top;
-    f = /*error:STATIC_TYPE_ERROR*/left;
+    f = /*error:STATIC_TYPE_ERROR*/right;
   }
 }
 ''');
   }
 
   void test_functionTypingAndSubtyping_higherOrderFunctionLiteral2() {
     checkFile('''
 class A {}
 class B extends A {}
 
@@ skipping 13 matching lines @@
     Function2<AToB, BToA> f; // Top
     f = top;
     f = left;
     f = right;
     f = bot;
   }
   {
     Function2<AToB, AToB> f; // Left
     f = /*error:STATIC_TYPE_ERROR*/top;
     f = left;
-    f = /*error:STATIC_TYPE_ERROR*/right;
+    f = /*error:INVALID_ASSIGNMENT*/right;
     f = bot;
   }
   {
     Function2<BToA, BToA> f; // Right
     f = /*error:STATIC_TYPE_ERROR*/top;
-    f = /*error:STATIC_TYPE_ERROR*/left;
+    f = /*error:INVALID_ASSIGNMENT*/left;
     f = right;
     f = bot;
   }
   {
     Function2<BToA, AToB> f; // Bot
     f = bot;
     f = /*error:STATIC_TYPE_ERROR*/left;
     f = /*error:STATIC_TYPE_ERROR*/top;
-    f = /*error:STATIC_TYPE_ERROR*/left;
+    f = /*error:STATIC_TYPE_ERROR*/right;
   }
 }
 ''');
   }
 
   void test_functionTypingAndSubtyping_higherOrderFunctionLiteral3() {
     checkFile('''
 class A {}
 class B extends A {}
 
@@ skipping 13 matching lines @@
     Function2<AToB, BToA> f; // Top
     f = top;
     f = left;
     f = right;
     f = bot;
   }
   {
     Function2<AToB, AToB> f; // Left
     f = /*error:STATIC_TYPE_ERROR*/top;
     f = left;
-    f = /*error:STATIC_TYPE_ERROR*/right;
+    f = /*error:INVALID_ASSIGNMENT*/right;
     f = bot;
   }
   {
     Function2<BToA, BToA> f; // Right
     f = /*error:STATIC_TYPE_ERROR*/top;
-    f = /*error:STATIC_TYPE_ERROR*/left;
+    f = /*error:INVALID_ASSIGNMENT*/left;
     f = right;
     f = bot;
   }
   {
     Function2<BToA, AToB> f; // Bot
     f = bot;
     f = /*error:STATIC_TYPE_ERROR*/left;
     f = /*error:STATIC_TYPE_ERROR*/top;
-    f = /*error:STATIC_TYPE_ERROR*/left;
+    f = /*error:STATIC_TYPE_ERROR*/right;
   }
 }
 ''');
   }
 
   void test_functionTypingAndSubtyping_higherOrderFunctionVariables() {
     checkFile('''
 class A {}
 class B extends A {}
 
 typedef T Function2<S, T>(S z);
 
 void main() {
   {
     Function2<Function2<A, B>, Function2<B, A>> top;
     Function2<Function2<B, A>, Function2<B, A>> right;
     Function2<Function2<A, B>, Function2<A, B>> left;
     Function2<Function2<B, A>, Function2<A, B>> bot;
 
     top = right;
     top = bot;
     top = top;
     top = left;
 
     left = /*warning:DOWN_CAST_COMPOSITE*/top;
     left = left;
     left =
-        /*warning:DOWN_CAST_COMPOSITE should be error:STATIC_TYPE_ERROR*/right;
+        /*error:INVALID_ASSIGNMENT*/right;
     left = bot;
 
     right = /*warning:DOWN_CAST_COMPOSITE*/top;
     right =
-        /*warning:DOWN_CAST_COMPOSITE should be error:STATIC_TYPE_ERROR*/left;
+        /*error:INVALID_ASSIGNMENT*/left;
     right = right;
     right = bot;
 
     bot = /*warning:DOWN_CAST_COMPOSITE*/top;
     bot = /*warning:DOWN_CAST_COMPOSITE*/left;
     bot = /*warning:DOWN_CAST_COMPOSITE*/right;
     bot = bot;
   }
 }
 ''');
@@ skipping 19 matching lines @@
     Function2<B, A> f;
     f = c.top;
     f = c.left;
     f = c.right;
     f = c.bot;
   }
   {
     Function2<B, B> f;
     f = /*warning:DOWN_CAST_COMPOSITE*/c.top;
     f = c.left;
-    f = /*warning:DOWN_CAST_COMPOSITE*/c.right;
+    f = /*error:INVALID_ASSIGNMENT*/c.right;
     f = c.bot;
   }
   {
     Function2<A, A> f;
     f = /*warning:DOWN_CAST_COMPOSITE*/c.top;
-    f = /*warning:DOWN_CAST_COMPOSITE*/c.left;
+    f = /*error:INVALID_ASSIGNMENT*/c.left;
     f = c.right;
     f = c.bot;
   }
   {
     Function2<A, B> f;
     f = /*warning:DOWN_CAST_COMPOSITE*/c.top;
     f = /*warning:DOWN_CAST_COMPOSITE*/c.left;
     f = /*warning:DOWN_CAST_COMPOSITE*/c.right;
     f = c.bot;
   }
@@ skipping 31 matching lines @@
     Top f;
     f = top;
     f = left;
     f = right;
     f = bot;
   }
   {
     Left f;
     f = /*warning:DOWN_CAST_COMPOSITE*/top;
     f = left;
-    f = /*warning:DOWN_CAST_COMPOSITE*/right; // Should we reject this?
+    f = /*error:INVALID_ASSIGNMENT*/right;
     f = bot;
   }
   {
     Right f;
     f = /*warning:DOWN_CAST_COMPOSITE*/top;
-    f = /*warning:DOWN_CAST_COMPOSITE*/left; // Should we reject this?
+    f = /*error:INVALID_ASSIGNMENT*/left;
     f = right;
     f = bot;
   }
   {
     Bot f;
     f = /*warning:DOWN_CAST_COMPOSITE*/top;
     f = /*warning:DOWN_CAST_COMPOSITE*/left;
     f = /*warning:DOWN_CAST_COMPOSITE*/right;
     f = bot;
   }
@@ skipping 130 matching lines @@
    num call(num x) => x;
 }
 int i2i(int x) => x;
 num n2n(num x) => x;
 void main() {
    {
      I2I f;
      f = new A();
      f = /*error:INVALID_ASSIGNMENT*/new B();
      f = i2i;
-     f = /*error:STATIC_TYPE_ERROR*/n2n;
+     f = /*error:INVALID_ASSIGNMENT*/n2n;
      f = /*warning:DOWN_CAST_COMPOSITE*/i2i as Object;
      f = /*warning:DOWN_CAST_COMPOSITE*/n2n as Function;
    }
    {
      N2N f;
      f = /*error:INVALID_ASSIGNMENT*/new A();
      f = new B();
-     f = /*error:STATIC_TYPE_ERROR*/i2i;
+     f = /*error:INVALID_ASSIGNMENT*/i2i;
      f = n2n;
      f = /*warning:DOWN_CAST_COMPOSITE*/i2i as Object;
      f = /*warning:DOWN_CAST_COMPOSITE*/n2n as Function;
    }
    {
      A f;
      f = new A();
      f = /*error:INVALID_ASSIGNMENT*/new B();
      f = /*error:INVALID_ASSIGNMENT*/i2i;
      f = /*error:INVALID_ASSIGNMENT*/n2n;
@@ skipping 41 matching lines @@
     Function2<B, A> f;
     f = C.top;
     f = C.left;
     f = C.right;
     f = C.bot;
   }
   {
     Function2<B, B> f;
     f = /*error:STATIC_TYPE_ERROR*/C.top;
     f = C.left;
-    f = /*error:STATIC_TYPE_ERROR*/C.right;
+    f = /*error:INVALID_ASSIGNMENT*/C.right;
     f = C.bot;
   }
   {
     Function2<A, A> f;
     f = /*error:STATIC_TYPE_ERROR*/C.top;
-    f = /*error:STATIC_TYPE_ERROR*/C.left;
+    f = /*error:INVALID_ASSIGNMENT*/C.left;
     f = C.right;
     f = C.bot;
   }
   {
     Function2<A, B> f;
     f = /*error:STATIC_TYPE_ERROR*/C.top;
     f = /*error:STATIC_TYPE_ERROR*/C.left;
     f = /*error:STATIC_TYPE_ERROR*/C.right;
     f = C.bot;
   }
@@ skipping 33 matching lines @@
     local = /*error:INVALID_ASSIGNMENT*/nonGenericFn;
   }
 }
 ''');
   }
 
   void test_functionTypingAndSubtyping_uninferredClosure() {
     checkFile('''
 typedef num Num2Num(num x);
 void main() {
-  Num2Num g = /*info:INFERRED_TYPE_CLOSURE,error:STATIC_TYPE_ERROR*/(int x) { return x; };
+  Num2Num g = /*info:INFERRED_TYPE_CLOSURE,error:INVALID_ASSIGNMENT*/(int x) { return x; };
   print(g(42));
 }
 ''');
   }
 
   void test_functionTypingAndSubtyping_void() {
     checkFile('''
 class A {
   void bar() => null;
   void foo() => bar(); // allowed
@@ skipping 1340 matching lines @@
   {
     lOfOs = mOfDs;
     lOfOs = mOfOs;
     lOfOs = mOfAs;
     lOfOs = lOfDs;
     lOfOs = lOfOs;
     lOfOs = lOfAs;
     lOfOs = new L<Object>(); // Reset type propagation.
   }
   {
-    lOfAs = /*warning:DOWN_CAST_COMPOSITE*/mOfDs;
+    lOfAs = /*error:INVALID_ASSIGNMENT*/mOfDs;
     lOfAs = /*error:INVALID_ASSIGNMENT*/mOfOs;
     lOfAs = mOfAs;
     lOfAs = /*warning:DOWN_CAST_COMPOSITE*/lOfDs;
     lOfAs = /*info:DOWN_CAST_IMPLICIT*/lOfOs;
     lOfAs = lOfAs;
     lOfAs = new L<A>(); // Reset type propagation.
   }
   {
     mOfDs = mOfDs;
     mOfDs = mOfOs;
     mOfDs = mOfAs;
     mOfDs = /*info:DOWN_CAST_IMPLICIT*/lOfDs;
     mOfDs = /*info:DOWN_CAST_IMPLICIT*/lOfOs;
-    mOfDs = /*warning:DOWN_CAST_COMPOSITE*/lOfAs;
+    mOfDs = /*error:INVALID_ASSIGNMENT*/lOfAs;
     mOfDs = new M(); // Reset type propagation.
   }
   {
     mOfOs = mOfDs;
     mOfOs = mOfOs;
     mOfOs = mOfAs;
     mOfOs = /*info:DOWN_CAST_IMPLICIT*/lOfDs;
     mOfOs = /*info:DOWN_CAST_IMPLICIT*/lOfOs;
     mOfOs = /*error:INVALID_ASSIGNMENT*/lOfAs;
     mOfOs = new M<Object>(); // Reset type propagation.
@@ skipping 566 matching lines @@
     // Regression test for https://github.com/dart-lang/sdk/issues/25069
     checkFile('''
 typedef int Foo();
 void foo() {}
 void main () {
   Foo x = /*error:INVALID_ASSIGNMENT,info:USE_OF_VOID_RESULT*/foo();
 }
 ''');
   }
 }