Java: Fix ClassInstanceExpr::isDiamond not working for anonymous classes

[Marcono1234]

Previously it was only working for non anonymous classes because it required that getType() instanceof ParameterizedClass which does not hold for anonymous classes.

[Marcono1234]

Possibly a bit irritating that the test is under /java7/ but now requires Java 9. But is this fine nonetheless since the diamond syntax was introduced in Java 7 (but extended in Java 9)?

[smowton]

@igfoo is there a quick fix for the Kotlin case rather than hack Kotlin source out like this? @Marcono1234 for clarity could you show a Kotlin snippet that otherwise behaves badly?

[Marcono1234]

If I omit that exclusion of Kotlin source files and then run the following query on the database for https://github.com/Kotlin/kotlinx.coroutines (latest database from GitHub was built with CodeQL CLI 2.16.1)

import java

from ClassInstanceExpr e
where
  e.isDiamond() and
  e.getCompilationUnit().isKotlinSourceFile()
select e

it finds for example this expression with an explicit type argument:
https://github.com/Kotlin/kotlinx.coroutines/blob/8c516f5ab1fcc39629d2838489598135eedd7b80/kotlinx-coroutines-core/common/test/AbstractCoroutineTest.kt#L13C25-L13C59

Though maybe the isDiamond predicate does not make sense for Kotlin in the first place; at least there is (to my knowledge) no <> syntax but instead the type arguments are simply omitted if they can be inferred by the compiler.
Or at least the name isDiamond might be a bit confusing then.

[igfoo]

Yep, that looks like a bug in our Kotlin support at the moment. Excluding like this looks fine for now. I've made an internal ticket to remind us to come back to this.