* `return` should only be added to the last statement if the return
type is not Unit
* If there is a `return` without an argument, then the expected return
type is Unit and the last expression is not a return argument (unless
it's an incomplete call, in which case it is inferred to return Unit;
this behavior is questionable, but inherited from K1)
* There should be a constraint on return arguments even if the expected
type is Unit, otherwise errors will be missed
* When the expected type is known, using the call completion results
writer is pointless (and probably subtly wrong).
^KT-54742 Fixed
Also remove incorrect subtype check checkers
Test unsafeVarianceInAliasedFunctionalType.kt started to fail because
of KT-54894. This bug existed before, changes from this commit just
unhided it (previously it was hidden because incorrect subtype check
in `isSubtypeForTypeMismatch` which is used by FirFunctionReturnTypeMismatchChecker
Several tests are affected by the usage of fixation direction calculator in FIR.
Restored to mimimize test data changes.
It is unnecessary in FE10 because a type variable with unknown type
is inferred into an error type, but affects test data in FIR where
Nothing/Any is selected by direction (as a temporary measure).
CR candidate in spec test is Unresolved in FIR because top-level CRs are resolved as call arguments.
Resolution ambiguity is also present in FE10 when CR is wrapped into an id call.
Introduce seven stages:
1) Analyze postponed arguments with fixed parameter types
2) Collect parameter types from constraints and lambda parameters' declaration
3) Fix not postponed variables for parameter types of all postponed arguments
4) Create atoms with revised expected types if needed
5) Analyze the first ready postponed argument and rerun stages if it has been analyzed
6) Force fixation remaining type variables: fix if possible or report not enough information
7) Force analysis remaining not analyzed postponed arguments and rerun stages if there are
^KT-37952 Fixed
^KT-32156 Fixed
^KT-37249 Fixed
^KT-37341 Fixed
Kirill Rakhman