Diagnostic tests for duplicate JVM signatures

compiler/testData/diagnostics/tests/duplicateJvmSignature/traitImpl/oneTrait.kt

@@ -0,0 +1,7 @@
+trait T {
+    fun getX() = 1
+}
+
+class C : T {
+    <!CONFLICTING_PLATFORM_DECLARATIONS!>val x = 1<!>
+}

compiler/testData/diagnostics/tests/duplicateJvmSignature/traitImpl/twoTraits.kt

@@ -0,0 +1,11 @@
+trait T1 {
+    fun getX() = 1
+}
+
+trait T2 {
+    val x: Int
+        get() = 1
+}
+
+<!CONFLICTING_PLATFORM_DECLARATIONS!>class C : T1, T2<!> {
+}