check Nothing type for all expressions not only for calls and simple names

(but excluding statement expressions)

compiler/testData/diagnostics/tests/controlFlowAnalysis/DeadCode.kt

@@ -0,0 +1,23 @@
+package c
+
+fun test1() {
+    <!UNREACHABLE_CODE!>val <!UNUSED_VARIABLE!>r<!>: Nothing = null!!<!>
+}
+
+fun test2(a: A) {
+    a + a
+    <!UNREACHABLE_CODE!>bar()<!>
+}
+
+fun test3() {
+    null!!
+    <!UNREACHABLE_CODE!>bar()<!>
+}
+
+fun throwNPE() = null!!
+
+class A {
+    fun plus(<!UNUSED_PARAMETER!>a<!>: A): Nothing = throw Exception()
+}
+
+fun bar() {}

compiler/testData/diagnostics/tests/generics/varProjection/setterProjectedOutAssign.kt

@@ -1,3 +1,5 @@
+// !DIAGNOSTICS: -UNREACHABLE_CODE -UNUSED_PARAMETER
+// t is unused due to KT-4233
 trait Tr<T> {
     var v: T
 }

compiler/testData/diagnostics/tests/generics/varProjection/setterProjectedOutNoPlusAssign.kt

@@ -1,3 +1,4 @@
+// !DIAGNOSTICS: -UNREACHABLE_CODE
 trait Tr<T> {
     var v: T
 }

compiler/testData/diagnostics/tests/generics/varProjection/setterProjectedOutPlusAssignDefined.kt

@@ -1,3 +1,4 @@
+// !DIAGNOSTICS: -UNREACHABLE_CODE
 trait Tr<T> {
     var v: T
 }

compiler/testData/diagnostics/tests/inference/regressions/kt2445.kt

@@ -7,4 +7,5 @@ fun main(args: Array<String>) {
     }
 }
 
-fun test<R>(callback: (R) -> Unit):Unit = callback(null!!)
+// callback is unused due to KT-4233
+fun test<R>(<!UNUSED_PARAMETER!>callback<!>: (R) -> Unit):Unit = <!UNREACHABLE_CODE!>callback(null!!)<!>