fix #28526 and fix #28527 FutureOr<T> in await and subtype

fix #28526, await FutureOr<T>
fix #28527, FutureOr<T> subtyping with type parameters

For subtyping: we've had a long standing issue in how inference reuses the <: operator code. Inference needs to make sure constraints are recorded on the type parameters we're inferring, but it also needs to correctly implement the future or union. This change addresses that & is a step towards the bigger inference change upcoming that tracks top/bottom constraints explicitly.

R=leafp@google.com

Committed: https://github.com/dart-lang/sdk/commit/39977ac6ec58516f5db5ac4df9fa2426fc19dac5

[Jennifer Messerly, 2017-01-27 20:54:59]

Description was changed from

==========
fix #28526, awiat FutureOr
==========

to

==========
fix #28526, await FutureOr<T>
fix #28527, FutureOr<T> interacts with type parameters
==========

[Jennifer Messerly, 2017-01-27 21:03:57]

Description was changed from

==========
fix #28526, await FutureOr<T>
fix #28527, FutureOr<T> interacts with type parameters
==========

to

==========
fix #28526, await FutureOr<T>
fix #28527, FutureOr<T> subtyping with type parameters

For subtyping: we've had a long standing issue in how inference reuses the <:
operator code. Inference needs to make sure constraints are recorded on the type
parameters we're inferring, but it also needs to correctly implement the future
or union. This change addresses that & is a step towards the bigger inference
change upcoming that tracks top/bottom constraints explicitly.
==========

[Jennifer Messerly, 2017-01-27 21:03:57]

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

[Jennifer Messerly, 2017-01-27 21:05:09]

Most of these test changes are from Bob, I've added a couple of cases. Thanks
Bob!

[Leaf, 2017-01-27 21:34:55]

lgtm

https://codereview.chromium.org/2655273008/diff/40001/pkg/analyzer/lib/src/ge...
File pkg/analyzer/lib/src/generated/type_system.dart (right):

https://codereview.chromium.org/2655273008/diff/40001/pkg/analyzer/lib/src/ge...
pkg/analyzer/lib/src/generated/type_system.dart:1556: // TODO(jmesserly): to
match old behavior, the trivial constraints are
What's the thing to be done in in this TODO?

https://codereview.chromium.org/2655273008/diff/40001/pkg/analyzer/test/gener...
File pkg/analyzer/test/generated/strong_mode_test.dart (right):

https://codereview.chromium.org/2655273008/diff/40001/pkg/analyzer/test/gener...
pkg/analyzer/test/generated/strong_mode_test.dart:1112: // Test a Future<T> can
be assigned to FutureOr<T>.
Comment is wrong?  Tests that await FutureOr<T> works?

[Jennifer Messerly, 2017-01-27 22:39:19]

thanks, fixed those comments

https://codereview.chromium.org/2655273008/diff/40001/pkg/analyzer/lib/src/ge...
File pkg/analyzer/lib/src/generated/type_system.dart (right):

https://codereview.chromium.org/2655273008/diff/40001/pkg/analyzer/lib/src/ge...
pkg/analyzer/lib/src/generated/type_system.dart:1556: // TODO(jmesserly): to
match old behavior, the trivial constraints are
On 2017/01/27 21:34:54, Leaf wrote:
> What's the thing to be done in in this TODO?  

it's not right once we pin based on downward constraints. So I need to fix it
then. (my other CL that hasn't landed yet.)

https://codereview.chromium.org/2655273008/diff/40001/pkg/analyzer/test/gener...
File pkg/analyzer/test/generated/strong_mode_test.dart (right):

https://codereview.chromium.org/2655273008/diff/40001/pkg/analyzer/test/gener...
pkg/analyzer/test/generated/strong_mode_test.dart:1112: // Test a Future<T> can
be assigned to FutureOr<T>.
On 2017/01/27 21:34:54, Leaf wrote:
> Comment is wrong?  Tests that await FutureOr<T> works?

I thought so too. It was from Bob's CL. Happy to fix.

[Jennifer Messerly, 2017-01-27 23:04:49]

Hi Leaf, can you take a quick look at the one small fix in TypeSystem.dart?

https://codereview.chromium.org/2655273008/diff/120001/pkg/analyzer/lib/src/g...
File pkg/analyzer/lib/src/generated/type_system.dart (right):

https://codereview.chromium.org/2655273008/diff/120001/pkg/analyzer/lib/src/g...
pkg/analyzer/lib/src/generated/type_system.dart:1498: bound.upper =
_typeSystem.getGreatestLowerBound(bound.upper,
this fix is new.

[Leaf, 2017-01-27 23:20:28]

lgtm.

[Jennifer Messerly, 2017-01-27 23:23:38]

Description was changed from

==========
fix #28526, await FutureOr<T>
fix #28527, FutureOr<T> subtyping with type parameters

For subtyping: we've had a long standing issue in how inference reuses the <:
operator code. Inference needs to make sure constraints are recorded on the type
parameters we're inferring, but it also needs to correctly implement the future
or union. This change addresses that & is a step towards the bigger inference
change upcoming that tracks top/bottom constraints explicitly.
==========

to

==========
fix #28526, await FutureOr<T>
fix #28527, FutureOr<T> subtyping with type parameters

For subtyping: we've had a long standing issue in how inference reuses the <:
operator code. Inference needs to make sure constraints are recorded on the type
parameters we're inferring, but it also needs to correctly implement the future
or union. This change addresses that & is a step towards the bigger inference
change upcoming that tracks top/bottom constraints explicitly.

R=leafp@google.com

Committed:
https://github.com/dart-lang/sdk/commit/39977ac6ec58516f5db5ac4df9fa2426fc19dac5
==========

[Jennifer Messerly, 2017-01-27 23:23:39]

Committed patchset #7 (id:120001) manually as
39977ac6ec58516f5db5ac4df9fa2426fc19dac5 (presubmit successful).