Irrelevant wildcard causes compile error

[TheTribalK]

Hi.

Since I updated to ecj 3.40.0.v20241118-1641 I get several new compile errors which seem wrong.

For reproduction:

private interface A<T extends B<T>> {
}

private interface B<T> {
  T getT();
}

public static void test() {
  A<?> a = null;
  test(a);
}

public static <T extends A<U>, U extends B<U>> void test(T a) {
}

compiles fine.

private interface A<T extends B<T, ?>> {
}

private interface B<T, U> {
  T getT();
}

public static void test() {
  A<?> a = null;
  test(a);
}

public static <T extends A<U>, U extends B<U, ?>> void test(T a) {
}

The addition of the irrelevant generic type argument U to B causes a compile error.

The method test(T) in the type Test is not applicable for the arguments (Test.A<capture#4-of ?>)

In my opinion this is a bug?

Thanks in advance.

[TheTribalK]

Same Problem in Version 3.39.0.v20240820-0604

[Madjosz]

Can confirm that the problematic code compiles with javac in all versions (tested 7 - 24).

Looks like a regression. Code compiles in ecj-3.38.0-20240408.235704-30 but fails in ecj-3.38.100-20240620.121349-13.

[stephan-herrmann]

This has been fixed in 4.38 - 2025-12 - ecj 3.44.0