Files
kotlin-fork/compiler/testData/codegen/box/polymorphicSignature/insideWhen.kt
T
Alexander Udalov 1cb1420e43 JVM: push down implicit coercion to Unit in IR
This is basically a workaround for a slightly different IR generated by
fir2ir vs psi2ir. Simplified, psi2ir generates something like this for
the sample from KT-59218:

  TRY type=Unit
    try: BLOCK type=Unit
      VAR methodHandle [...]
      TYPE_OP type=Unit origin=IMPLICIT_COERCION_TO_UNIT
        CALL invokeExact [...]

While fir2ir generates the following:

  TYPE_OP type=Unit origin=IMPLICIT_COERCION_TO_UNIT
    TRY type=Any?
      try: BLOCK type=Any?
        VAR methodHandle [...]
        CALL invokeExact [...]

The lowering relies on the fact that a polymorphic call (`invokeExact`
in this case) is a direct argument to the TYPE_OP, to determine the
correct return type (Unit in this case) to be generated in the bytecode.

The solution here is to push the type coercion "through" all the
block-like structures (`try`, `when`, container expression) so that if
the last statement in the block is a polymorphic call, it gets properly
converted even if the whole block is under a type coercion operation, as
it happens in fir2ir. We achieve that by using the "data" parameter of
the IR transformer: appropriate immediate children of
IrTypeOperatorCall/IrTry/IrWhen/IrContainerExpression get the type that
the expression needs to be coerced to, and all the other expressions
ignore that type and set it to null when transforming their children.

A proper solution would be to ensure fir2ir generates exactly the same
IR as psi2ir (KT-59781), but since PolymorphicSignatureLowering is the
only lowering affected so far, and polymorphic calls occur very rarely,
it seems safe to workaround it in the lowering for now.

 #KT-59218 Fixed
2023-07-18 11:37:42 +00:00

26 lines
450 B
Kotlin
Vendored

// TARGET_BACKEND: JVM
// WITH_STDLIB
// FULL_JDK
import java.lang.invoke.MethodHandles
import java.lang.invoke.MethodType
object O {
fun main() {}
}
fun f() = 2
fun box(): String {
when (f()) {
1 -> {}
2 -> {
val mh = MethodHandles.lookup().findVirtual(O::class.java, "main", MethodType.methodType(Void.TYPE))
mh.invokeExact(O)
}
3 -> {}
else -> {}
}
return "OK"
}