Adjusts dart2js SSA builder to tolerate method type arguments.

Adjusts dart2js SSA builder to tolerate method type arguments.

This CL changes `Types.getClassContext` to return null for method type
arguments (indicating that the given `type` does not contain any type
variables, which fits the current "ignore them" approach to that kind
of type variable). It introduces a new class `MethodTypeVariableType`
which models a method type variables and ensures that it is treated
as `dynamic` (such that type annotations are permissive, and usages
as a type expression `T` in `.. is T` or `.. as T` are treated like
a malformed type). For RTI, method type variables are ignored (such
that no additional classes are claimed to be needed for RTI due to
method type variables, no matter how they are used). Finally,
`SsaBuilder.addTypeVariableReference` generates code yielding the
value `dynamic` for method type variables.

Adresses issue 26436.

R=johnniwinther@google.com

Committed: https://github.com/dart-lang/sdk/commit/ee926fac8dd4fbc1b1cec9c8e836be916baf81b1

[eernst, 2016-05-11 12:42:18]

eernst@google.com changed reviewers:
+ johnniwinther@google.com

[eernst, 2016-05-11 12:42:18]

Needs sanity checking at builder.dart:4773-4779, which may touch invariants that
I don't know about (the test cases do not fail, though).

[Johnni Winther, 2016-05-11 12:58:30]

lgtm

https://codereview.chromium.org/1969753002/diff/1/pkg/compiler/lib/src/ssa/bu...
File pkg/compiler/lib/src/ssa/builder.dart (right):

https://codereview.chromium.org/1969753002/diff/1/pkg/compiler/lib/src/ssa/bu...
pkg/compiler/lib/src/ssa/builder.dart:4769: } else if (type is
MethodTypeVariableType) {
I think this should be the first test, so that we do not try to access the rti
value from elsewhere.

Maybe add a test for something like:

class Class<S> {
  factory Class(S s) { 
    foo<T>(var) => t is T; // Don't look for T in Class
    foo<S>(s);
  }
}

[eernst, 2016-05-11 13:04:24]

Description was changed from

==========
Adjusts dart2js SSA builder to tolerate method type arguments.

This CL changes `Types.getClassContext` to return null for method type
arguments (indicating that the given `type` does not contain any type
variables, which fits the current "ignore them" approach to that kind
of type variable). It introduces a new class `MethodTypeVariableType`
which models a method type variables and ensures that it is treated
as `dynamic` (such that type annotations are permissive, and usages
as a type expression `T` in `.. is T` or `.. as T` are treated like
a malformed type). For RTI, method type variables are ignored (such
that no additional classes are claimed to be needed for RTI due to
method type variables, no matter how they are used). Finally,
`SsaBuilder.addTypeVariableReference` generates code yielding the
value `dynamic` for method type variables.

Adresses issue 26436.
==========

to

==========
Adjusts dart2js SSA builder to tolerate method type arguments.

This CL changes `Types.getClassContext` to return null for method type
arguments (indicating that the given `type` does not contain any type
variables, which fits the current "ignore them" approach to that kind
of type variable). It introduces a new class `MethodTypeVariableType`
which models a method type variables and ensures that it is treated
as `dynamic` (such that type annotations are permissive, and usages
as a type expression `T` in `.. is T` or `.. as T` are treated like
a malformed type). For RTI, method type variables are ignored (such
that no additional classes are claimed to be needed for RTI due to
method type variables, no matter how they are used). Finally,
`SsaBuilder.addTypeVariableReference` generates code yielding the
value `dynamic` for method type variables.

Adresses issue 26436.

R=johnniwinther@google.com

Committed:
https://github.com/dart-lang/sdk/commit/ee926fac8dd4fbc1b1cec9c8e836be916baf81b1
==========

[eernst, 2016-05-11 13:04:25]

Committed patchset #1 (id:1) manually as
ee926fac8dd4fbc1b1cec9c8e836be916baf81b1 (presubmit successful).