RFR: 8356942: invokeinterface Throws AbstractMethodError Instead of IncompatibleClassChangeError [v2]

[Coleen Phillimore]

On Tue, 8 Jul 2025 07:10:24 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> In [JDK-8186092](https://bugs.openjdk.org/browse/JDK-8186092) (way back in JDK 10) we elided loader constraint checks for overpass methods related to default methods by skipping them when initializing the itable for the interface. But that was the wrong thing to do. The overpass method is setup when there is a resolution/selection error so that the correct exception is thrown if the problematic method is invoked (like the ICCE reporting conflicting methods) and by eliding that entry we instead get the `AbstractMethhodError`.
>> 
>> The fix here is to revert that change from [JDK-8186092](https://bugs.openjdk.org/browse/JDK-8186092), and to address the loader constraint problem by adding the same check for overpass methods in `klassItable::check_constraints` that exists for `klassVtable::check_constraints`.
>> 
>> Testing:
>>  - modified existing regression test
>>  - tiers 1-4
>> 
>> EDIT: originally there was a new regression test for this, but this area is already covered by the `vmTestBase` "`defmeth` tests. That test was missing the necessary invocation modes to expose the bug, so they have been added.
>> 
>> Thanks
>> 
>> PS. The diff is much smaller if you disable whitespace differences.
>
> David Holmes has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Replaced new test by updating existing defmeth case that was missing the invokeinterface variants of the
>   test scenario. Also updated all tests therein to use `throwsExact` so that the wrong kind of ICCE does not
>   cause the test to pass by mistake.

test/hotspot/jtreg/vmTestbase/vm/runtime/defmeth/ConflictingDefaultsTest.java line 86:

> 84:      * TEST: C c = new C(); c.m() ==> ICCE
> 85:      * TEST: I c = new C(); c.m() ==> ICCE
> 86:      * TEST: J c = new C(); c.m() ==> ICCE

So this is the generator code that generates the defmeth tests, but iirc, the tests are regenerated and the generated tests were the ones checked in and run.

And shouldn't the test from commit 87e30fd80172c5bd6748f140ddf6cd19adb62764 now fail?

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PR Review Comment: https://git.openjdk.org/jdk/pull/26122#discussion_r2192297473