strong_mode.dart: remove extra asserts and throw

strong_mode.dart: remove extra asserts and throw
this was an old TODO we discussed a while back

R=brianwilkerson@google.com

Committed: https://github.com/dart-lang/sdk/commit/f82b8ae978edb85d31d87e93708c70a2d958c625

[Jennifer Messerly, 2016-01-16 00:30:58]

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

[Jennifer Messerly, 2016-01-16 00:30:58]

I was cleaning out old local branches, and found this basically finished CL for
a while ago. :)

BTW, there's further design discussion about "as" checks. They seem to be used
in a bunch of places, for better or worse. Ideally we could tighten the types of
the *Impl element model classes to return *Impl types, which would allow us to
avoid a lot of the downcasts.

Another idea was changing the "type" setter on fields, so the synthetic
getter/setter are automatically populated.

But those are a bit larger refactorings so I didn't want to tackle it without
running it by someone first.

[Jennifer Messerly, 2016-01-16 00:31:18]

On 2016/01/16 00:30:58, John Messerly wrote:
> I was cleaning out old local branches, and found this basically finished CL
for
> a while ago. :)
> 
> BTW, there's further design discussion about "as" checks. They seem to be used
> in a bunch of places, for better or worse. Ideally we could tighten the types
of
> the *Impl element model classes to return *Impl types, which would allow us to
> avoid a lot of the downcasts.
> 
> Another idea was changing the "type" setter on fields, so the synthetic
> getter/setter are automatically populated.
> 
> But those are a bit larger refactorings so I didn't want to tackle it without
> running it by someone first.

s/for a while ago/from a while ago/

[Brian Wilkerson, 2016-01-18 17:37:57]

LGTM

> Ideally we could tighten the types of the *Impl element model classes
> to return *Impl types, which would allow us to avoid a lot of the
> downcasts.

I'm not sure we can, given that summaries are being implemented by creating a
second implementation class for some of the element classes. We'll have to see
what the summaries work requires.

[Jennifer Messerly, 2016-01-19 16:45:36]

On 2016/01/18 17:37:57, Brian Wilkerson wrote:
> LGTM
> 
> > Ideally we could tighten the types of the *Impl element model classes
> > to return *Impl types, which would allow us to avoid a lot of the
> > downcasts.
> 
> I'm not sure we can, given that summaries are being implemented by creating a
> second implementation class for some of the element classes. We'll have to see
> what the summaries work requires.

That makes sense. But in that case, we probably won't want to downcast to *Impl
either, right? Because it would blow up.

There's got to be some way to express the static structure so casts aren't
necessary. Maybe we need an (internal) interface for "mutable elements"?

[Brian Wilkerson, 2016-01-19 16:57:44]

> There's got to be some way to express the static structure so casts aren't
> necessary. Maybe we need an (internal) interface for "mutable elements"?

I've been contemplating such a thing, I'll start a separate thread so we can
pull Paul in. Whatever we do, we have a lot of references to Impl classes to
clean up, so I wouldn't let that stop you from landing this CL.

[Jennifer Messerly, 2016-01-19 17:18:04]

Description was changed from

==========
strong_mode.dart: remove extra asserts and throw
this was an old TODO we discussed a while back
==========

to

==========
strong_mode.dart: remove extra asserts and throw
this was an old TODO we discussed a while back

R=brianwilkerson@google.com

Committed:
https://github.com/dart-lang/sdk/commit/f82b8ae978edb85d31d87e93708c70a2d958c625
==========

[Jennifer Messerly, 2016-01-19 17:18:05]

Committed patchset #2 (id:20001) manually as
f82b8ae978edb85d31d87e93708c70a2d958c625 (presubmit successful).