8287885: Local classes cause ClassLoader error if the type names are similar but not same

[archiecobbs]

The compiler doesn't really support case-insensitive filesystems. However, we can still avoid name clashes for local classes because their names are synthesized with indexed names like$1, $2, etc.

So previously, a class like this:

public class Test {

    void method1() {
        enum ABC { A, B, C; };
    }

    void method2() {
        enum Abc { A, B, C; };
    } 
}

would generate these classfiles:

Test.class
Test$1ABC.class
Test$1Abc.class

the latter two of which clash on case-insensitive filesystems. After this patch, these non-clashing classfiles are generated instead:

Test.class
Test$1ABC.class
Test$2Abc.class

The only thing slightly wonky about this patch is that clearLocalClassNameIndexes() since local classes ABC and Abc share the same index, clearing either one clears both. But this is harmless, because these indexes are cleared in a batch, during a final "cleanup" step after processing the containing class.

To avoid any locale weirdness, we only collapse ASCII letters A-Z/a-z. So this is clearly a limited, tactical fix.

---

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Issue

• JDK-8287885: Local classes cause ClassLoader error if the type names are similar but not same

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Webrevs

• 00: Full (68a76851)

[archiecobbs]

Withdrawing this PR - too much of a hack and it doesn't really solve the underlying problem.

To be discussed further on compiler-dev.