fix #26992, inference failures are now an error

fix #26992, inference failures are now an error

R=leafp@google.com

Committed: https://github.com/dart-lang/sdk/commit/f57ed4d8945427ab03d54a2bd449fbb2201391fd

[Jennifer Messerly, 2016-08-30 16:42:02]

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

[Leaf, 2016-08-30 21:41:37]

lgtm

https://codereview.chromium.org/2295853002/diff/20001/pkg/analyzer/lib/src/ge...
File pkg/analyzer/lib/src/generated/type_system.dart (right):

https://codereview.chromium.org/2295853002/diff/20001/pkg/analyzer/lib/src/ge...
pkg/analyzer/lib/src/generated/type_system.dart:1453: // the actually lower
type, result type it's more likely to be
To be pedantic, I don't think either is guaranteed to be lower.  They can be
completely unrelated, right?

https://codereview.chromium.org/2295853002/diff/20001/pkg/analyzer/test/src/t...
File pkg/analyzer/test/src/task/strong/inferred_type_test.dart (right):

https://codereview.chromium.org/2295853002/diff/20001/pkg/analyzer/test/src/t...
pkg/analyzer/test/src/task/strong/inferred_type_test.dart:1696: var nameInfo =
"";//!!!(upwards == "Future") ? "" : "/*error:COULD_NOT_INFER*/";
Is this vestigial debugging code?

[Jennifer Messerly, 2016-09-01 20:31:19]

Thanks! Not sure if you want to take another look. Happy to tweak the wording as
well in a follow up :)

https://codereview.chromium.org/2295853002/diff/20001/pkg/analyzer/lib/src/ge...
File pkg/analyzer/lib/src/generated/type_system.dart (right):

https://codereview.chromium.org/2295853002/diff/20001/pkg/analyzer/lib/src/ge...
pkg/analyzer/lib/src/generated/type_system.dart:1453: // the actually lower
type, result type it's more likely to be
On 2016/08/30 21:41:37, Leaf wrote:
> To be pedantic, I don't think either is guaranteed to be lower.  They can be
> completely unrelated, right?

Doh. Yeah, great point. I wonder if it would be worth GLB or LUB to pick a type?
It's such guesswork because we know the code is erroneous...

I think the reason this heuristic worked here is because the "lower" bound tends
to come from passed-in things (arguments) vs the "upper" bound that tends to
come from return value. When an error happens, we put the blame on the
arguments, rather than the context type.

I will try and clarify the comment at least :)

https://codereview.chromium.org/2295853002/diff/20001/pkg/analyzer/test/src/t...
File pkg/analyzer/test/src/task/strong/inferred_type_test.dart (right):

https://codereview.chromium.org/2295853002/diff/20001/pkg/analyzer/test/src/t...
pkg/analyzer/test/src/task/strong/inferred_type_test.dart:1696: var nameInfo =
"";//!!!(upwards == "Future") ? "" : "/*error:COULD_NOT_INFER*/";
On 2016/08/30 21:41:37, Leaf wrote:
> Is this vestigial debugging code?  

yeah. fixed!

[Jennifer Messerly, 2016-09-01 20:38:15]

Description was changed from

==========
fix #26992, inference failures are now an error
==========

to

==========
fix #26992, inference failures are now an error

R=leafp@google.com

Committed:
https://github.com/dart-lang/sdk/commit/f57ed4d8945427ab03d54a2bd449fbb2201391fd
==========

[Jennifer Messerly, 2016-09-01 20:38:16]

Committed patchset #3 (id:40001) manually as
f57ed4d8945427ab03d54a2bd449fbb2201391fd (presubmit successful).

[vsm, 2016-09-01 20:48:59]

On 2016/09/01 20:38:16, John Messerly wrote:
> Committed patchset #3 (id:40001) manually as
> f57ed4d8945427ab03d54a2bd449fbb2201391fd (presubmit successful).

DBC - consider running ./tools/build_sdk.sh whenever you change inference :-)

[Jennifer Messerly, 2016-09-01 20:54:41]

On 2016/09/01 20:48:59, vsm wrote:
> On 2016/09/01 20:38:16, John Messerly wrote:
> > Committed patchset #3 (id:40001) manually as
> > f57ed4d8945427ab03d54a2bd449fbb2201391fd (presubmit successful).
> 
> DBC - consider running ./tools/build_sdk.sh whenever you change inference :-)

oh nice, that's a thing now. yay!