Before this commit, K2 always applied coercion-to-unit for
callable references if expected type was Unit, and actual non-Unit.
However, this may not work in case when actual return type is
a type parameter and it must be inferred into Unit.
In this commit we started to disallow coercion-to-unit
for references with synthetic outer call (~ top-level in K1)
AND a type parameter as a return type (both should be true to disallow).
This provides better K1 consistency,
while still keeping some broken K1 cases working in K2.
See also added comment in CallableReferenceResolution.kt.
#KT-62565 Fixed
When reporting INFERRED_TYPE_VARIABLE_INTO_EMPTY_INTERSECTION, search
for a call to a declaration with the type parameter that got inferred
into an empty intersection inside the expression.
#KT-56377 Fixed
Note: here we set sinceVersion = null for this feature.
However, we plan in 1.9.* - 2.0 time frame to solve KT-56377
and to enable this feature in 2.0, the latest in 2.1.
When expected type is known, use it as expected type for branch bodies.
While it indeed becomes different from the usual select call resolution,
where expected type is applied only after completion starts,
it helps to support, e.g. callable references resolution just as powerful
as it was in K1.
Also, in some cases where diagnostics have been changed, they become
a bit more helpful since they are reported closer
to the problematic places
cannotCastToFunction.kt test has been removed because it relied
on the case erroneously supported by the hack removed from
the FirCallResolver in this commit.
^KT-45989 Fixed
^KT-55936 Fixed
^KT-56445 Fixed
^KT-54709 Related
^KT-55931 Related
For example, NEW_INFERENCE_NO_INFORMATION_FOR_PARAMETER
It became especially relevant after 0e84bf2053
that together with later commits bring a lot of unnecessary
NEW_INFERENCE_NO_INFORMATION_FOR_PARAMETER diagnostic
Apparently if you add an empty line at the start of the FIR file, that's
not enough of a difference for the test suite to complain about, but
enough for it to not add the FIR_IDENTICAL directive...
While it is theoretically useful to know that `{ while(true) {} }`
returns Nothing, CFG node deadness is not precise enough to do that: if
the entire lambda is dead, it's no longer possible to find out whether
the loop is terminating. Besides, `while (true)` and `if (true)` are
pretty much the only constructs like that anyway.
Note that this commit does not affect resolution for lambdas that end in
a Nothing-returning expression, e.g. `throw`.
* `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
This directive anyway does not make test run twice with OI, and with NI
It only once run the test with specific settings (// LANGUAGE)
and ignores irrelevant (OI or NI tags)
Update includes:
- Changing syntax of `OI/`NI` tags from `<!NI;TAG!>` to `<!TAG{NI}!>`
- Fix some incorrect directives
- Change order of diagnostics in some places
- Remove ignored diagnostics from FIR test data (previously `DIAGNOSTICS` didn't work)
- Update FIR dumps in some places and add `FIR_IDENTICAL` if needed
- Replace all JAVAC_SKIP with SKIP_JAVAC directive
Don't add `Unit` if variable has an upper constraint T <: A.
It's impossible to coerce variable T to Unit as constraint system will
be always contradictory: T := Unit => Unit should be subtype of A
#KT-39900 Fixed
Coersion to Unit from error type leads to misleading type mismatches:
"expected <expected lambda return type> found Unit", despite no user-provided Unit / empty lambda.
These diagnostics were collected, but not reported before, and that had been disguising the issue for a while.
KT-34729 Fixed
Expression will be checked against expected type later.
Theoretically, this is not very good, but it aligns with the old
inference, plus it helps avoiding multiple type mismatch diagnostics.
Mikhail Glukhikh