RFR: 8365676: javac incorrectly allows calling interface static method via type variable
Chen Liang
liach at openjdk.org
Sat Aug 30 00:44:21 UTC 2025
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.
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Commit messages:
- 8365676: javac incorrectly allows calling interface static method via type variable
Changes: https://git.openjdk.org/jdk/pull/27015/files
Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27015&range=00
Issue: https://bugs.openjdk.org/browse/JDK-8365676
Stats: 30 lines in 3 files changed: 27 ins; 0 del; 3 mod
Patch: https://git.openjdk.org/jdk/pull/27015.diff
Fetch: git fetch https://git.openjdk.org/jdk.git pull/27015/head:pull/27015
PR: https://git.openjdk.org/jdk/pull/27015
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