If the right-hand side of an equality comparison contains an assignment
to the variable used in the left-hand side, then implications about the
equality comparison within data-flow analysis cannot be applied, as the
value of the variable will be different after the comparison.
^KT-55096 Fixed
If a certain type statement is true on loop entry and all continue
paths, then it is also true on exit if the condition did not reassign
the variable.
^KT-7676 tag fixed-in-k2
`x?.y != null` does not imply that `x != null` if e.g. an argument to
`y` has reassigned `x` in the meantime.
The same is true for `x == y` and `functionWithContract(x, y)`, but
those are somewhat harder to implement since there is no easy way to
find the last node of a certain argument.
^KT-55096
val c = C("...")
val d = c
if (c.x == null) return
c.x.length // c.x has type String
d.x.length // d.x -> c.x through d -> c
c = C(null) // remove alias d -> c
d.x.length // info from c.x moved to d.x
^KT-54824 Fixed
For example:
val c = C("...")
val x = c.x // alias to variable for c.x, which depends on c
if (x == null) return
// now c.x has type Any
c = C(null)
// c has been reassigned => info for c.x is no longer valid;
// c itself has never had any statements made about it, but
// we must still call removeAllAboutVariable to clear the
// dependents
Handling try/catch and break/continue is too hard here, and failing to
do that properly can create incorrect smartcast. Better be conservative
and assume all code is live.
The logic should clear back aliases as well. To ensure all back aliases
don't lose any information, statements on the original variable are
copied over to its aliases.
The fix is a bit hacky, but it's very simple. In addition, it still does
not handle the case where the receiver is a lambda function. But such
case seems to be fairly rare in practice.
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)
To do so, inside the root cause of inapplicable candidate errors,
we will record expected/actual type of receiver, if any.
That will help identifying inapplicable calls on nullable receiver.
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
Nikolay Lunyak