Forbid private functions with no body and private properties in traits which are abstract by default

compiler/testData/cli/jvm/multipleTextRangesInDiagnosticsOrder.out

@@ -10,4 +10,7 @@ compiler/testData/cli/jvm/multipleTextRangesInDiagnosticsOrder.kt:6:14: error: m
 compiler/testData/cli/jvm/multipleTextRangesInDiagnosticsOrder.kt:6:24: error: modifier 'private' is incompatible with 'override'
     override protected private val c: Int
                        ^
+compiler/testData/cli/jvm/multipleTextRangesInDiagnosticsOrder.kt:6:24: error: abstract property in an interface cannot be private
+    override protected private val c: Int
+                       ^
 COMPILATION_ERROR

compiler/testData/diagnostics/tests/modifiers/privateInInterface.kt

@@ -0,0 +1,12 @@
+interface My {
+    <!PRIVATE_PROPERTY_IN_TRAIT!>private<!> val x: Int
+    <!INCOMPATIBLE_MODIFIERS!>private<!> <!ABSTRACT_MODIFIER_IN_TRAIT, INCOMPATIBLE_MODIFIERS!>abstract<!> val xx: Int
+    private val xxx: Int
+        get() = 0
+    <!FINAL_PROPERTY_IN_TRAIT, DEPRECATED_MODIFIER_CONTAINING_DECLARATION!>final<!> val y: Int
+    <!DEPRECATED_MODIFIER_CONTAINING_DECLARATION!>final<!> val yy: Int
+        get() = 1
+    <!PRIVATE_FUNCTION_WITH_NO_BODY!>private<!> fun foo(): Int
+    // ok
+    private fun bar() = 42
+}

compiler/testData/diagnostics/tests/modifiers/privateInInterface.txt

@@ -0,0 +1,14 @@
+package
+
+public interface My {
+    private abstract val x: kotlin.Int
+    private abstract val xx: kotlin.Int
+    private final val xxx: kotlin.Int
+    public final val y: kotlin.Int
+    public final val yy: kotlin.Int
+    private final fun bar(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    private abstract fun foo(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/variance/Visibility.kt

@@ -2,7 +2,7 @@ interface Test<in I, out O> {
     val internal_val: <!TYPE_VARIANCE_CONFLICT!>I<!>
     public val public_val: <!TYPE_VARIANCE_CONFLICT!>I<!>
     <!DEPRECATED_MODIFIER_CONTAINING_DECLARATION!>protected<!> val protected_val: <!TYPE_VARIANCE_CONFLICT!>I<!>
-    private val private_val: I
+    <!PRIVATE_PROPERTY_IN_TRAIT!>private<!> val private_val: I
 
     var interlan_private_set: <!TYPE_VARIANCE_CONFLICT!>O<!>
         private set
@@ -10,11 +10,11 @@ interface Test<in I, out O> {
         private set
     <!DEPRECATED_MODIFIER_CONTAINING_DECLARATION!>protected<!> var protected_private_set: <!TYPE_VARIANCE_CONFLICT!>O<!>
         private set
-    private var private_private_set: O
+    <!PRIVATE_PROPERTY_IN_TRAIT!>private<!> var private_private_set: O
         private set
 
     fun internal_fun(i: <!TYPE_VARIANCE_CONFLICT!>O<!>) : <!TYPE_VARIANCE_CONFLICT!>I<!>
     public fun public_fun(i: <!TYPE_VARIANCE_CONFLICT!>O<!>) : <!TYPE_VARIANCE_CONFLICT!>I<!>
     <!DEPRECATED_MODIFIER_CONTAINING_DECLARATION!>protected<!> fun protected_fun(i: <!TYPE_VARIANCE_CONFLICT!>O<!>) : <!TYPE_VARIANCE_CONFLICT!>I<!>
-    private fun private_fun(i: O) : I
+    <!PRIVATE_FUNCTION_WITH_NO_BODY!>private<!> fun private_fun(i: O) : I
 }

compiler/testData/loadJava/compiledKotlin/fun/InheritMethodsDifferentReturnTypesAndVisibilities.kt

@@ -2,11 +2,11 @@ package test
 
 public interface Super1 {
     public fun foo(): CharSequence
-    private fun bar(): String
+    private fun bar(): String = ""
 }
 
 public interface Super2 {
-    private fun foo(): String
+    private fun foo(): String = ""
     public fun bar(): CharSequence
 }
 

compiler/testData/loadJava/compiledKotlin/fun/InheritMethodsDifferentReturnTypesAndVisibilities.txt

@@ -6,11 +6,11 @@ public interface Sub : test.Super1, test.Super2 {
 }
 
 public interface Super1 {
-    private abstract fun bar(): kotlin.String
+    private final fun bar(): kotlin.String
     public abstract fun foo(): kotlin.CharSequence
 }
 
 public interface Super2 {
     public abstract fun bar(): kotlin.CharSequence
-    private abstract fun foo(): kotlin.String
+    private final fun foo(): kotlin.String
 }