remove obsolete UninferredClosure type

pkg/analyzer/lib/src/task/strong/info.dart

Index: pkg/analyzer/lib/src/task/strong/info.dart
diff --git a/pkg/analyzer/lib/src/task/strong/info.dart b/pkg/analyzer/lib/src/task/strong/info.dart
index d9c912600eaab412ce05292c1655c62663fd9cc3..6dd5318be9991042762c9f81c8dab8b6b720d67f 100644
--- a/pkg/analyzer/lib/src/task/strong/info.dart
+++ b/pkg/analyzer/lib/src/task/strong/info.dart
@@ -129,11 +129,6 @@ abstract class DownCast extends CoercionInfo {
       // runtime.
       return new StaticTypeError(rules, expression, toT, reason: reason);
     }
-    if (expression is FunctionExpression) {
-      // fromT should be an exact type - this will almost certainly fail at
-      // runtime.
-      return new UninferredClosure(rules, expression, cast);
-    }

[vsm, 2016/01/22 22:51:29]

Can you try this test with and without your change:

typedef num Num2Num(num x);

void main() {
  Num2Num g = (int x) { return x; };

  print(g(42));
}

?

I think this would trigger the uninferred closure path - it should just be a
StaticTypeError though.

[Jennifer Messerly, 2016/01/22 23:26:07]

Without:
[warning] (int x) {return x;} ((int) → num) will need runtime check to cast to
type (num) → num (/Users/jmesserly/scratch/test.dart, line 5, col 15)

With:
[warning] (int x) {return x;} ((int) → num) will need runtime check to cast to
type (num) → num (/Users/jmesserly/scratch/test.dart, line 5, col 15)

[vsm, 2016/01/22 23:34:14]

Should be an error, not warning, right?  The runtime cast will definitely fail. 
How about folding into the previous:

if (expression is Literal || expression is FunctionExpression) {
  // fromT should be an exact type - this will almost certainly fail at
  // runtime.
 return new StaticTypeError(rules, expression, toT, reason: reason);
}

?

[Jennifer Messerly, 2016/01/22 23:49:52]

Hmmm. I did that but it didn't have any effect. It seems like this isn't the
code path we're going down in your example. Will need to investigate further.

[Jennifer Messerly, 2016/01/25 23:40:29]

Ah, I think perhaps my rebuild just failed (I was using analyzer_cli). I've
added a test in checker_test to demonstrate the fix. Here's results after a
successful rebuild:

[error] Type check failed: (int x) {return x;} ((int) → num) is not of type
(num) → num because (int x) {return x;} cannot be typed as (num) → num
(/Users/jmesserly/scratch/test.dart, line 3, col 76)

     if (expression is InstanceCreationExpression) {
       ConstructorElement e = expression.staticElement;
       if (e == null || !e.isFactory) {
@@ -565,23 +560,3 @@ class StaticTypeError extends StaticError {
   @override
   String get name => 'STRONG_MODE_STATIC_TYPE_ERROR';
 }
-
-//
-// Temporary "casts" of allocation sites - literals, constructor invocations,
-// and closures.  These should be handled by contextual inference.  In most
-// cases, inference will be sufficient, though in some it may unmask an actual
-// error: e.g.,
-//   List<int> l = [1, 2, 3]; // Inference succeeds
-//   List<String> l = [1, 2, 3]; // Inference reveals static type error
-// We're marking all as warnings for now.
-//
-// TODO(vsm,leafp): Remove this.
-class UninferredClosure extends DownCast {
-  UninferredClosure(TypeSystem rules, FunctionExpression expression, Cast cast)
-      : super._internal(rules, expression, cast);
-
-  @override
-  String get name => 'STRONG_MODE_UNINFERRED_CLOSURE';
-
-  toErrorCode() => new StaticTypeWarningCode(name, message);
-}