Frontend support for function as expression

compiler/testData/diagnostics/tests/functionAsExpression/Common.kt

@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+annotation class ann(val name: String)
+val ok = "OK"
+
+class A
+
+val withName = fun name() {}
+val extensionWithName = fun A.name() {}
+val withoutName = fun () {}
+val extensionWithoutName = fun A.() {}
+
+fun withAnnotation() = [ann(ok)] fun () {}
+val withReturn = fun (): Int { return 5}
+val withExpression = fun() = 5
+val funfun = fun() = fun() = 5
+
+val parentesized = (fun () {})
+val parentesizedWithType = (fun () {}) : () -> Unit
+val withType = (fun () {}) : () -> Unit