fix #28630, instance method tear-offs are treated as strict arrows

fix #28630, instance method tear-offs are treated as strict arrows

R=leafp@google.com

Committed: https://github.com/dart-lang/sdk/commit/ac85576979a199b3d9307448077a2792eec7acff

[Jennifer Messerly, 2017-02-03 20:12:06]

jmesserly@google.com changed reviewers:
+ leafp@google.com

[Leaf, 2017-02-03 20:28:41]

https://codereview.chromium.org/2675963004/diff/20001/pkg/analyzer/lib/src/ta...
File pkg/analyzer/lib/src/task/strong/checker.dart (right):

https://codereview.chromium.org/2675963004/diff/20001/pkg/analyzer/lib/src/ta...
pkg/analyzer/lib/src/task/strong/checker.dart:1085: if (hasStrictArrow(expr)) {
This needs to stay isKnownFunction (see my comment in the next file).

https://codereview.chromium.org/2675963004/diff/20001/pkg/analyzer/test/src/t...
File pkg/analyzer/test/src/task/strong/checker_test.dart (right):

https://codereview.chromium.org/2675963004/diff/20001/pkg/analyzer/test/src/t...
pkg/analyzer/test/src/task/strong/checker_test.dart:1677: f =
/*error:INVALID_CAST_METHOD*/c.top;
This isn't right.    This error is only for casts that are guaranteed to fail. 
Here,  c could be a subtype of C which tightens the return type so that the cast
will succeed.

[Jennifer Messerly, 2017-02-03 21:02:50]

https://codereview.chromium.org/2675963004/diff/20001/pkg/analyzer/test/src/t...
File pkg/analyzer/test/src/task/strong/checker_test.dart (right):

https://codereview.chromium.org/2675963004/diff/20001/pkg/analyzer/test/src/t...
pkg/analyzer/test/src/task/strong/checker_test.dart:1677: f =
/*error:INVALID_CAST_METHOD*/c.top;
On 2017/02/03 20:28:41, Leaf wrote:
> This isn't right.    This error is only for casts that are guaranteed to fail.

> Here,  c could be a subtype of C which tightens the return type so that the
cast
> will succeed.

yeah, that's why I'd split out like that initially. Happy to keep the
distinction, though I may just inline that "hasKnownFunction" method so we don't
hit the problem again of using it inappropriately.

Eventually we want to remove implicit casts though, right? at which point it
will become an error?

[Jennifer Messerly, 2017-02-03 21:05:41]

PTAL, I've addressed your comments :)

[Leaf, 2017-02-03 21:17:51]

lgtm

[Jennifer Messerly, 2017-02-03 21:21:27]

Description was changed from

==========
fix #28630, instance method tear-offs are treated as strict arrows
==========

to

==========
fix #28630, instance method tear-offs are treated as strict arrows

R=leafp@google.com

Committed:
https://github.com/dart-lang/sdk/commit/ac85576979a199b3d9307448077a2792eec7acff
==========

[Jennifer Messerly, 2017-02-03 21:21:28]

Committed patchset #4 (id:60001) manually as
ac85576979a199b3d9307448077a2792eec7acff (presubmit successful).