RFR: JDK-8277451: java.lang.reflect.Field::set on static field with invalid argument type should throw IAE

[Jaikiran Pai]

On Sat, 20 Nov 2021 19:13:43 GMT, Mandy Chung <mchung at openjdk.org> wrote:

> java.lang.reflect.Field::set on static field with invalid argument type should throw IAE.  But this regression is introduced by JEP 416 throwing NPE instead.
> 
> `ensureObj` is called as the first check of the `Field::set` method to ensure the receiver object is checked first before the argument.   For a Field instance with write-access, the method handle invocation will check the receiver.  Therefore for `Field::setXXX` methods to set a primitive value, `ensureObj` is only called if it's a read-only Field instance to ensure IllegalArgumentException is thrown first before IllegalAccessException to keep the existing behavior to avoid duplicated receiver check.

src/java.base/share/classes/jdk/internal/reflect/MethodHandleFieldAccessorImpl.java line 72:

> 70:      */
> 71:     protected IllegalArgumentException newGetIllegalArgumentException(Object o) {
> 72:         return new IllegalArgumentException(getMessage(true, o != null ? o.getClass().getName() : ""));

Hello Mandy,
With this change the `getMessage` may get passed an empty string, so it would end up printing something like `Can not get ... field <fieldname> on`. Do you think the `getMessage` implementation should be tweaked not to print the "on" if the `attemptedType` is empty?

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PR: https://git.openjdk.java.net/jdk/pull/6490