[FIR] Add tests highlighting false errors in K2 regarding equalities

Some overlooked corner-cases found by Denis.

compiler/testData/diagnostics/testsWithStdLib/equalityCompatibilityCommonCases.fir.kt

@@ -96,3 +96,17 @@ fun incompatibleIdentityRegardlessNullabilityWithValueClassesSmartCast(c: Any?,
         <!FORBIDDEN_IDENTITY_EQUALS_WARNING!>c === d<!>
     }
 }
+
+enum class F
+
+fun <T: E, K: F> incompatibleEnumComparisonWithTypeParameters(e: T, f: K) {
+    <!INCOMPATIBLE_ENUM_COMPARISON_ERROR!>e == f<!>
+}
+
+interface A
+enum class G : B
+
+fun <I : A> incompatibleEnumAndUnrelatedInterfaceThroughTypeParameter(x: G?, i: I?) {
+    <!INCOMPATIBLE_ENUM_COMPARISON_ERROR!>x == i<!>
+}
+

compiler/testData/diagnostics/testsWithStdLib/equalityCompatibilityCommonCases.kt

@@ -96,3 +96,17 @@ fun incompatibleIdentityRegardlessNullabilityWithValueClassesSmartCast(c: Any?,
         c === d
     }
 }
+
+enum class F
+
+fun <T: E, K: F> incompatibleEnumComparisonWithTypeParameters(e: T, f: K) {
+    e == f
+}
+
+interface A
+enum class G : B
+
+fun <I : A> incompatibleEnumAndUnrelatedInterfaceThroughTypeParameter(x: G?, i: I?) {
+    x == i
+}
+