[FIR] KT-55552: Ensure type mismatch is missing

compiler/testData/diagnostics/tests/delegationTypeMismatch.fir.kt

@@ -0,0 +1,13 @@
+// ISSUE: KT-55552
+
+interface B2 {
+  fun d()
+}
+
+class B
+
+open class C(b: B) : B2 by b {} //no error in K2, K1 - [TYPE_MISMATCH] Type mismatch: inferred type is B but B2 was expected
+
+fun main() {
+  val c = C(B()).d() //runtime AbstractMethodError
+}

compiler/testData/diagnostics/tests/delegationTypeMismatch.kt

@@ -0,0 +1,13 @@
+// ISSUE: KT-55552
+
+interface B2 {
+  fun d()
+}
+
+class B
+
+open class C(b: B) : B2 by <!TYPE_MISMATCH!>b<!> {} //no error in K2, K1 - [TYPE_MISMATCH] Type mismatch: inferred type is B but B2 was expected
+
+fun main() {
+  val c = C(B()).d() //runtime AbstractMethodError
+}