This new kind of expression encompasses the nullability of the original
expression after null check (or equivalent `is Nothing?` check).
Unlike FirExpressionWithSmartcast, this expression won't be materialized
during conversion to backend IR. Also, Nothing? is discarded when
computing the intersection of possible types from smartcast info.
In that way, Nothing? is not used during resolution, while such
smartcast info is stored in it (and the expression kind itself).
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
This commit adds diagnostics for the following
* DELEGATE_SPECIAL_FUNCTION_MISSING
* DELEGATE_SPECIAL_FUNCTION_AMBIGUITY
* DELEGATE_SPECIAL_FUNCTION_NONE_APPLICABLE
Previously if an unsafe call is to an overloaded function, FIR checkers
report NONE_APPLICABLE. This change instead report them as UNSAFE_CALL
or its variants.
Previously unsafe call is reported as part of InapplicableWrongReceiver.
This makes it difficult for the downstream checkers to report different
diagnostics.
Specifically, the report the following 4 errors.
* NON_VARARG_SPREAD
* ARGUMENT_PASSED_TWICE
* TOO_MANY_ARGUMENTS
* NO_VALUE_FOR_PARAMETER
Also added/updated the following position strategies.
* NAME_OF_NAMED_ARGUMENT
* VALUE_ARGUMENTS
Currently, FIR reports errors caused by previous resolution failure. For
example with unresolved `a` and `b` in code `a.b`, both `a` and `b` are
highlighted. FE1.0 only highlights `a` since it's the root cause. This
change applies this heuristics when reporting FirDiagnostics.
Mikhail Glukhikh