http://cr.openjdk.java.net/~vlivanov/8036117/webrev.00/
https://bugs.openjdk.java.net/browse/JDK-8036117
84 lines changed: 74 ins; 3 del; 7 mod
I have to revert a cleanup I did for 8027827.
MethodHandle.invokeWithArguments (and generic invocation) has
unpleasant
peculiarity in behavior when used with VarargsCollector. So,
unfortunately, invokeWithArguments is not an option there.
Looking at the API (excerpts from javadoc [1] [2]), the following
condition doesn't hold in that case:
"trailing parameter type of the caller is a reference type
identical
to or assignable to the trailing parameter type of the adapter".
Example:
target.invokeWithArguments((Object[])args)
=>
target.invoke((Object)o1,(Object)o2,(Object)o3)
=/>
target.invokeExact((Object)o1, (Object)o2, (Object[])o3)
because Object !<: Object[].
The fix is to skip unnecessary conversion when invoking a method
handle
and just do a pairwise type conversion.
Testing: failing test case, nashorn w/ experimental features (octane)
Thanks!
Best regards,
Vladimir Ivanov
[1] MethodHandle.invokeWithArguments
"Performs a variable arity invocation, ..., as if via an inexact
invoke
from a call site which mentions only the type Object, and whose
arity is
the length of the argument array."
[2] MethodHandle.asVarargsCollector
"When called with plain, inexact invoke, if the caller type is the
same
as the adapter, the adapter invokes the target as with invokeExact.
(This is the normal behavior for invoke when types match.)
Otherwise, if the caller and adapter arity are the same, and the
trailing parameter type of the caller is a reference type
identical to
or assignable to the trailing parameter type of the adapter, the
arguments and return values are converted pairwise, as if by
asType on a
fixed arity method handle.
Otherwise, the arities differ, or the adapter's trailing parameter
type
is not assignable from the corresponding caller type. In this
case, the
adapter replaces all trailing arguments from the original trailing
argument position onward, by a new array of type arrayType, whose
elements comprise (in order) the replaced arguments."
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