fix #27284, allow FutureUnionType to be preserved during generic inference

fix #27284, allow FutureUnionType to be preserved during generic inference

R=leafp@google.com

Committed: https://github.com/dart-lang/dev_compiler/commit/7b5e6be4a82b831751dee8e4728b8b8bd4e870c0

[Jennifer Messerly, 2016-10-18 01:22:02]

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

[Leaf, 2016-10-18 19:42:38]

lgtm.

https://codereview.chromium.org/2425143002/diff/40001/pkg/analyzer/lib/src/ge...
File pkg/analyzer/lib/src/generated/type_system.dart (right):

https://codereview.chromium.org/2425143002/diff/40001/pkg/analyzer/lib/src/ge...
pkg/analyzer/lib/src/generated/type_system.dart:1595: lowerBound =
DynamicTypeImpl.instance;
This is probably true as it stands, but it feels a little fragile.  A == bottom
breaks this if we start allowing bottom, and if we stop flattening, then
Future<Future<A>> | Future<A> also breaks it.  What about using LUB here?

[Jennifer Messerly, 2016-10-18 22:55:33]

Description was changed from

==========
fix #27284, allow FutureUnionType to be preserved during generic inference
==========

to

==========
fix #27284, allow FutureUnionType to be preserved during generic inference

R=leafp@google.com

Committed:
https://github.com/dart-lang/dev_compiler/commit/7b5e6be4a82b831751dee8e4728b...
==========

[Jennifer Messerly, 2016-10-18 22:55:34]

Committed patchset #3 (id:40001) manually as
7b5e6be4a82b831751dee8e4728b8b8bd4e870c0 (presubmit successful).

[Jennifer Messerly, 2016-10-18 22:55:42]

thanks!

https://codereview.chromium.org/2425143002/diff/40001/pkg/analyzer/lib/src/ge...
File pkg/analyzer/lib/src/generated/type_system.dart (right):

https://codereview.chromium.org/2425143002/diff/40001/pkg/analyzer/lib/src/ge...
pkg/analyzer/lib/src/generated/type_system.dart:1595: lowerBound =
DynamicTypeImpl.instance;
On 2016/10/18 19:42:38, Leaf wrote:
> This is probably true as it stands, but it feels a little fragile.  A ==
bottom
> breaks this if we start allowing bottom, and if we stop flattening, then
> Future<Future<A>> | Future<A> also breaks it.  What about using LUB here?

Good catch. I originally had it doing an LUB, not sure why I changed it. Fixed &
also fixed comment wording. :)