Fix analyzer's treatment of mixin constructors.

Fix analyzer's treatment of mixin constructors.

This changes analyzer to match the spec (and the VM behavior) with
regard to which base class constructors are forwarded through mixin
applications: only those constructors that take zero optional
parameters are forwarded.  In addition, the tests in tests/language/
are updated to match analyzer and the VM.

There is one small difference between analyzer and the VM behavior:
the spec says that if no constructors are forwarded at all, then the
mixin application will automatically acquire an implicit default
constructor.  The VM behavior is to issue an error in this
circumstance.  After consulting with Gilad, it seems like the VM
behavior is more consistent with the intent, so I've chosen to make
analyzer and the tests match the VM behavior, in the hopes that the
spec can be changed accordingly.

Should we change our minds in the future and decide that we want to
keep the spec as is, the tests and analyzer behavior can easily be
changed.

BUG=dartbug.com/19576
R=brianwilkerson@google.com

Committed: https://code.google.com/p/dart/source/detail?r=41645

[Paul Berry, 2014-11-07 01:02:53]

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

[Paul Berry, 2014-11-07 01:02:53]

Note: this will fix bug 19576 and render bug 13641 obsolete.

See also bug 15101.

[Brian Wilkerson, 2014-11-07 16:59:32]

https://codereview.chromium.org/707073002/diff/20001/pkg/analyzer/lib/src/gen...
File pkg/analyzer/lib/src/generated/error.dart (right):

https://codereview.chromium.org/707073002/diff/20001/pkg/analyzer/lib/src/gen...
pkg/analyzer/lib/src/generated/error.dart:1435: "parameter.");
I find this message to be confusing and think that users will too. The "this
class" refers to the class containing the mixins, but we're not creating
constructors for that class, we're creating constructors for the implicit
superclass of that class.

https://codereview.chromium.org/707073002/diff/20001/pkg/analyzer/test/genera...
File pkg/analyzer/test/generated/compile_time_error_code_test.dart (right):

https://codereview.chromium.org/707073002/diff/20001/pkg/analyzer/test/genera...
pkg/analyzer/test/generated/compile_time_error_code_test.dart:1403:
CompileTimeErrorCode.MIXIN_HAS_NO_CONSTRUCTORS]);
It would be good to disable the second error if the first has already been
produced because it seems like a duplicate to me.

[Brian Wilkerson, 2014-11-07 17:10:12]

LGTM

[Paul Berry, 2014-11-07 17:31:01]

https://codereview.chromium.org/707073002/diff/20001/pkg/analyzer/lib/src/gen...
File pkg/analyzer/lib/src/generated/error.dart (right):

https://codereview.chromium.org/707073002/diff/20001/pkg/analyzer/lib/src/gen...
pkg/analyzer/lib/src/generated/error.dart:1435: "parameter.");
On 2014/11/07 16:59:32, Brian Wilkerson wrote:
> I find this message to be confusing and think that users will too. The "this
> class" refers to the class containing the mixins, but we're not creating
> constructors for that class, we're creating constructors for the implicit
> superclass of that class.

Good point.  I've changed it to "This mixin application is invalid because all
of the constructors in the base class '{0}' have optional parameters."

https://codereview.chromium.org/707073002/diff/20001/pkg/analyzer/test/genera...
File pkg/analyzer/test/generated/compile_time_error_code_test.dart (right):

https://codereview.chromium.org/707073002/diff/20001/pkg/analyzer/test/genera...
pkg/analyzer/test/generated/compile_time_error_code_test.dart:1403:
CompileTimeErrorCode.MIXIN_HAS_NO_CONSTRUCTORS]);
On 2014/11/07 16:59:32, Brian Wilkerson wrote:
> It would be good to disable the second error if the first has already been
> produced because it seems like a duplicate to me.

Good point.  I'll do this in a follow-up CL, as well as the other improvements
we discussed in person.

[Paul Berry, 2014-11-10 19:28:54]

Committed patchset #3 (id:40001) manually as 41645 (presubmit successful).