RFR: 8365676: javac incorrectly allows calling interface static method via type variable [v2]

[Chen Liang]

On Wed, 3 Sep 2025 21:07:48 GMT, Chen Liang <liach at openjdk.org> wrote:

>> The interface static methods added in Java 8 are never inherited in method resolution. However, javac incorrectly allowed them to be resolved against type variables with an interface as its only upper bound, which violates JLS 4.9:
>> 
>>> The members of an intersection type are the members of the class or interface it induces.
>> 
>> Combined with JLS 4.4:
>> 
>>> The members of a type variable X with bound T & I1 & ... & In are the members of the intersection type ([§4.9](https://docs.oracle.com/javase/specs/jls/se24/html/jls-4.html#jls-4.9)) T & I1 & ... & In appearing at the point where the type variable is declared
>> 
>> Last time this piece of code in Attr was updated was around Java 7, so this was probably missed in Java 8.
>> 
>> The test cases added showcases wrong ways to refer to interface static methods: `Collator`, a subtype of `Comparator`, cannot use `reverseOrder`, so shouldn't type variable `T` bounded by `Comparator<Integer>` be able to do so.
>> 
>> In addition, the error for private member access on type variables should probably have been symbol not found instead of access errors - we might revisit that later. I made the new error symbol not found for parity with interface static reference on classes, as showcased in the compiler output in this new test.
>
> Chen Liang has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:
> 
>  - Break up long conditional, add intersection bounded test case
>  - Merge branch 'master' of https://github.com/openjdk/jdk into fix/typevar-inherit-interface-static
>  - 8365676: javac incorrectly allows calling interface static method via type variable

I have created the CSR https://bugs.openjdk.org/browse/JDK-8366848. Please help review.

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PR Comment: https://git.openjdk.org/jdk/pull/27015#issuecomment-3251755049