Thanks to https://bugs.openjdk.org/browse/JDK-8369517, I can now close several long-standing issues in #IntelliJIDEA bug tracker as 'third-party issue'. People reported that IntelliJ erroneously highlights compilable code as red. But it was not our mistake. The code in question should not be compilable, according to the specification! This is fixed in Java 26, so your code may become broken there.