member visibility inheritance; check visibility is not weaken added

compiler/testData/diagnostics/tests/scopes/visibility_inherit_modifier.jet

@@ -0,0 +1,85 @@
+package b
+
+open class A {
+    internal open fun foo() {}
+}
+
+class B : A() {
+    <!CANNOT_CHANGE_ACCESS_PRIVILEGE!>protected<!> override fun foo() {}
+}
+
+class C : A() {
+    internal override fun foo() {}
+}
+
+//------------
+open class D {
+    private open fun self() : D = this
+}
+
+class E : D() {
+    internal override fun self() = this
+
+    fun test() {
+        val <!UNUSED_VARIABLE!>s<!> : E = self()
+    }
+}
+
+//------------
+open class F {
+    protected open fun protected_fun() {}
+}
+
+class G : F() {
+    override fun protected_fun() {}
+}
+
+fun test_fun_stays_protected(g: G) {
+    g.<!UNRESOLVED_REFERENCE!>protected_fun<!>()
+}
+
+//------------
+open class H {
+    internal protected open fun pi_fun() {}
+}
+
+class I : H() {
+    protected override fun pi_fun() {}
+}
+
+class J : H() {
+    internal override fun pi_fun() {}
+}
+
+class K : H() {
+    public override fun pi_fun() {}
+}
+
+//-------------
+trait T {
+    public fun foo() {}
+}
+
+open class L : T {
+    override fun foo() {}
+}
+
+class M : L() {
+    <!CANNOT_WEAKEN_ACCESS_PRIVILEGE!>internal<!> override fun foo() {}
+}
+//---------------
+trait R {
+    internal protected fun foo() {}
+}
+
+trait P : R {
+    internal override fun foo() {}
+}
+
+trait Q : R {
+    protected override fun foo() {}
+}
+
+class S : P, Q {
+    <!CANNOT_CHANGE_ACCESS_PRIVILEGE!>internal<!> override fun foo() {}
+}