If a type variable T is used in an `is` or `as` expression (e.g.
`42 is T` or `42 as T`) or is part of a subtype check, then any types
which may be substituted for T via instantiation must also be treated as
participating in a type check.
This CL ensures that the RTI need computation includes type arguments
for those substituted types and that those types are included in the
list of implicit checks.
Additionally, in order for this to work, this CL fixes a bug in which
the impact transformer was failing to register generic instantiations
occurring in (partial) constants.
Fixes: https://github.com/dart-lang/sdk/issues/45046
Change-Id: I98ae0eca0adcbbb26cdd664318da0da578b289b5
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/190460
Reviewed-by: Stephen Adams <sra@google.com>
Commit-Queue: Mayank Patke <fishythefish@google.com>
The current implementation of this check is incorrect and produces false
negatives. Conservatively assuming that one type is always a potential
subtype of another is a simple fix to get this working.
The main downsides are that we may emit signatures and provide type
arguments to functions even when they're not needed because we no longer
statically deduce that a type check must fail. This may cause size
regressions.
I've added a TODO to add proper constraint solving per the local type
inference spec, but this is not currently a priority since no regression
is observed on large Google apps.
Change-Id: Ie5065596331c33a030e06e66481f258ef937e659
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/155544
Reviewed-by: Stephen Adams <sra@google.com>
Commit-Queue: Mayank Patke <fishythefish@google.com>
Mayank Patke