NI. Coerce return type of lambda function descriptor to Unit. #KT-30242 Fixed

compiler/testData/diagnostics/tests/inference/coercionToUnit/kt30242.kt

@@ -0,0 +1,64 @@
+// !WITH_NEW_INFERENCE
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+// ISSUE: KT-30242
+
+class A
+
+fun println(s: String = "") {}
+
+fun foo(f: () -> Any) {}
+
+fun test1(b: Boolean) {
+    foo {
+        if (b) {
+            println("meh")
+        }
+    }
+}
+
+fun test2(b: Boolean) {
+    foo {
+        when {
+            b -> println("meh")
+        }
+    }
+}
+
+fun test3(b: Boolean) {
+    foo {
+        <!INVALID_IF_AS_EXPRESSION!>if<!> (b) {
+            return@foo A()
+        }
+    }
+}
+
+fun test4(b: Boolean) {
+    foo {
+        if (b) {
+            return@foo println("meh")
+        }
+
+        if (b) {
+            println()
+        }
+    }
+}
+
+fun bar(block: () -> String) {}
+
+fun test_5(b: Boolean) {
+    bar {
+        <!NI;TYPE_MISMATCH, TYPE_MISMATCH!>if (b) {
+            println("meh")
+        }<!>
+    }
+}
+
+fun test_6(b: Boolean) {
+    foo {
+        if (b) {
+            return@foo Unit
+        }
+        if (b) {}
+    }
+}