Using `kotlin.jvm.functions.Function{n+1}` (via
`getJvmSuspendFunctionClass`) for suspend functions was wrong in the
function reference lowering, because we didn't adapt the parameter types
by transforming the last type to Continuation and adding Object, and
generic signature ended up being incorrect.
Actually there was no need to use `kotlin.jvm.functions.Function{n+1}`
at all. We can just use the built-in
`kotlin.coroutines.SuspendFunction{n}` as a supertype, and it will be
mapped correctly later in codegen. It's not even needed to add the
`kotlin.coroutines.jvm.internal.SuspendFunction` marker manually, since
it's also handled by the codegen (see `IrTypeMapper.mapClassSignature`).
#KT-48732 Fixed
Keeping the origin as LOCAL_FUNCTION_FOR_LAMBDA was a mistake as this
tells codegen nothing. Changing the origin in allows, for example,
removing the hack that detaches inline lambdas from the IR tree before
verification and codegen, or treating inline lambdas and inline
anonymous functions the same way.
This includes fake functions created for inline callable references.
#KT-48319 Fixed
#KT-47279 Fixed?
The condition on the relationship between the current class and the type
of the receiver for protected members was the opposite of what the JVMS
says, and yet somehow mostly worked?
#KT-48331 Fixed
#KT-20542 Fixed
Do not check, that all Unit predecessors are POPs. This is safe for the
same reason, as it is safe to allow some of ARETURN sources not be
suspension point results.
To elaborate, before Unit, the stack is empty. This is because if there
are multiple paths to Unit and at least one of them comes from POP after
suspension point (we are interested in this case only - otherwise, the
call is not tail-call), in path from said POP the stack is empty, since
after suspension point the stack contains only one element. Thus, the
stack in other paths leading to Unit has to be empty, otherwise, merge
operation is not possible and ASM will report error during analysis.
Since the stack is empty in all paths, we can hoist Unit and following
ARETURN to predecessors, effectively turning path from suspension point
to tail-call.
Meaning, they never need continuation objects. This shouldn't affect
correctness (if the assumption is valid, the continuation object
should always have been removed in the end), but the phantom
continuation sometimes left behind unused accessors (and in case of
inline function references, those accessors would refer to non-existent
functions) - see the modified test and Kotlin/kotlinx.coroutines#2769.
Forbid mixing suspend and non-suspend functional supertypes.
Since JVM BE generates suspend functional types as non-suspend ones
with SuspendFunction marker interface, there is not way to distinguish
non-suspend functional type from suspend one if they are mixed.
#KT-18707 Fixed
Coroutine transform would occasionally *extend* the range of a
local instead of shrinking it (if the next suspension point
is after the end point for the local). That leads to the local
variable table having a local that covers code where it is not
defined. That is invalid and leads to D8 removing the locals
table from the code.
Igor Laevsky