The compiler should only report diagnostics for
comparisons over builtins and identity-less types,
other incompatibilities should be reported
via inspections.
It's ok that in `equalityChecksOnIntegerTypes`
instead of `EQUALITY_NOT_APPLICABLE_WARNING` we get
`EQUALITY_NOT_APPLICABLE`, because
`ProperEqualityChecksInBuilderInferenceCalls`
is already active by default.
This change also replaces the notion of a representative superclass
with the least upper bound.
This makes complex types like
intersection/flexible transparent to
RULES1-based compatibility checks.
One way to look at it is to think
that this is an automatic way of handling
type parameters: automatic picking of
"interesting" bounds, and checking them against one another.
Note that `TypeIntersector.intersectTypes`
for `Int` and `T` where `T` is a type parameter
may return both `{Int & T}` or `null`
depending on `T`-s bounds. At the same time,
for type parameters `T` and `K` it will
always return `{T & K}`.
`ConeTypeIntersector.intersectTypes`, on the
other hand, will always return `{Int & T}`
irrespectively of the bounds. Meaning, the two
intersectors differ in corner cases.
`lowerBoundIfFlexible` call in `isLiterallyTypeParameter` is backed by
the `equalityOfFlexibleTypeParameters` test.
^KT-35134 #fixed-in-k2
^KT-22499 #fixed-in-k2
^KT-46383 #fixed-in-k2
Added checker for FirEqualityOperatorCall. It's surfaced as one of the
following diagnostics depending on the PSI structure and types under
comparison:
* INCOMPATIBLE_TYPES(_WARNING)
* EQUALITY_NOT_APPLICABLE(_WARNING)
* INCOMPATIBLE_ENUM_COMPARISON_ERROR
Comparing with FE1.0, the current implementation is more conservative
and only highlights error if the types are known to follow certain
contracts with `equals` method. Otherwise, the checker reports warnings
instead.
However, the current checker is more strict in the following situations:
1. it now rejects incompatible enum types like `Enum<E1>` and
`Enum<E2>`, which was previously accepted
2. it now rejects incompatible class types like `Class<String>` and
`Class<Int>`, which was previously accepted
3. the check now takes smart cast into consideration, so
`if (x is String) x == 3` is now rejected
Previously helpers from checkType.kt was in special package, and
if directive was enabled then test runner (`AbstractDiagnosticTest`)
injected additional imports to test files and removed them after test
was completed.
It's very hard to support such behavior in new test infrastructure so
there was a decision about changing `CHECK_TYPE`:
1. All helpers from `checkType.kt` now stays in default package
2. `CHECK_TYPE` only adds `checkType.kt` to set of analyzed files
and don't modify their content
For test which are written in default package (most of tests actually)
there are no changes. On the other hand if there is a test where dev
want to use checkType functions in testfile with some package then he
should explicitly import functions which he needed (`checkSubtype`,
`checkType`, `_`)
Nikolay Lunyak