This seems a good improvement. I created
https://bugs.openjdk.java.net/browse/JDK-8267509 for this issue.
How did you run into this illegal varargs method? Is that class file
generated at runtime?
Mandy
On 5/20/21 10:18 AM, x4e_x4e wrote:
Hello,
If a MethodHandles.Lookup is used to locate a MethodHandle for a varargs method
who's final parameter is not an array an IllegalArgumentException will be
thrown:
java.lang.IllegalArgumentException: not an array type: int
at
java.base/java.lang.invoke.MethodHandleStatics.newIllegalArgumentException(MethodHandleStatics.java:138)
at
java.base/java.lang.invoke.MethodHandle.spreadArrayChecks(MethodHandle.java:1066)
at
java.base/java.lang.invoke.MethodHandle.asCollectorChecks(MethodHandle.java:1259)
at
java.base/java.lang.invoke.MethodHandle.asVarargsCollector(MethodHandle.java:1427)
at
java.base/java.lang.invoke.MethodHandle.withVarargs(MethodHandle.java:1111)
at
java.base/java.lang.invoke.MethodHandle.setVarargs(MethodHandle.java:1634)
at
java.base/java.lang.invoke.MethodHandles$Lookup.getDirectMethodCommon(MethodHandles.java:3755)
at
java.base/java.lang.invoke.MethodHandles$Lookup.getDirectMethod(MethodHandles.java:3691)
at
java.base/java.lang.invoke.MethodHandles$Lookup.findStatic(MethodHandles.java:2399)
This makes sense, however it seems that the exception is swallowed and instead
a generic IllegalAccessException is thrown:
Caused by: java.lang.IllegalAccessException: cannot make variable arity:
package.Class.method(Object[],int)Object/invokeStatic
at
java.base/java.lang.invoke.MemberName.makeAccessException(MemberName.java:957)
at
java.base/java.lang.invoke.MethodHandle.setVarargs(MethodHandle.java:1636)
at
java.base/java.lang.invoke.MethodHandles$Lookup.getDirectMethodCommon(MethodHandles.java:3755)
at
java.base/java.lang.invoke.MethodHandles$Lookup.getDirectMethod(MethodHandles.java:3691)
at
java.base/java.lang.invoke.MethodHandles$Lookup.findStatic(MethodHandles.java:2399)
It would probably be helpful to make the IllegalAccessException caused by the
IllegalArgumentException, or at the very least add it as a suppressed exception.
Otherwise the only way to find the helpful exception here is through runtime
debugging.
Relevant code:
https://github.com/openjdk/jdk/blob/7b98400c81900a8c779394d549b5fb61f1dd8638/src/java.base/share/classes/java/lang/invoke/MethodHandle.java#L1635
Thanks,
x4e
