usingComparator / isEqualTo fails due to Comparator inferred type parameter

[scordio]

Describe the bug

usingComparator does not work properly with certain combinations of numeric comparators from java.util.Comparator.

• AssertJ Core version: 3.23.1
• Java version: 11
• Test framework version: JUnit 5.8.2

Test case reproducing the bug

This:

assertThat(4L)
  .usingComparator(Comparator.comparingDouble(Number::doubleValue))
  .isEqualTo(4.0d);

and this:

Comparator<Long> comparator = Comparator.comparingDouble(Number::doubleValue);

assertThat(4L)
  .usingComparator(comparator)
  .isEqualTo(4.0d);

fail with:

java.lang.ClassCastException: class java.lang.Double cannot be cast to class java.lang.Long (java.lang.Double and java.lang.Long are in module java.base of loader 'bootstrap')

But this:

Comparator<Number> comparator = Comparator.comparingDouble(Number::doubleValue);

assertThat(4L)
  .usingComparator(comparator)
  .isEqualTo(4.0d);

and this:

Comparator comparator = Comparator.comparingDouble(Number::doubleValue); // raw type warning

assertThat(4L)
  .usingComparator(comparator) // unchecked warning
  .isEqualTo(4.0d);

work properly.

[Michael1993]

This is the same issue I encountered in this PR (#664). You pass a Comparator<? super Long> to your class but compare two Objects at runtime, making Java assume that your arguments are both Long, leading to a ClassCastException.

[Michael1993]

I think this can be solved by removing the type arguments of the Comparator passed to usingComparator. This shouldn't lead to any issue (I think?) because it's used to create a ComparatorBasedComparisonStrategy, which uses a rawtype Comparator anyways.