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
Mikhail Glukhikh
2680c8effd