Effects: add diagnostic tests on contracts

- Make AbstractDiagnosticsTest dump function contracts
- Add diagnostics tests on parsing contracts
- Add diagnostics tests on smartcats in presence of functions with
contracts
- Add diagnostics tests on initialization and flow in presence of
in-place called lambdas

==========
Introduction of EffectSystem: 16/18

compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/when/withSubject.kt

@@ -0,0 +1,35 @@
+// !LANGUAGE: +ReturnsEffect
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.internal.contracts.*
+
+fun isString(x: Any?): Boolean {
+    contract {
+        returns(true) implies (x is String)
+    }
+    return x is String
+}
+
+fun exhaustive(x: Any?) {
+    when (isString(x)) {
+        true -> <!DEBUG_INFO_SMARTCAST!>x<!>.length
+        false -> x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+
+    when(!isString(x)) {
+        true -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        false -> <!DEBUG_INFO_SMARTCAST!>x<!>.length
+    }
+}
+
+fun smartcastInElse(x: Any?) {
+    when (isString(x)) {
+        false -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        else -> <!DEBUG_INFO_SMARTCAST!>x<!>.length
+    }
+
+    when (!isString(x)) {
+        true -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        else -> <!DEBUG_INFO_SMARTCAST!>x<!>.length
+    }
+}

compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/when/withSubject.txt

@@ -0,0 +1,7 @@
+package
+
+public fun exhaustive(/*0*/ x: kotlin.Any?): kotlin.Unit
+public fun isString(/*0*/ x: kotlin.Any?): kotlin.Boolean
+    Returns(TRUE) -> x is String
+
+public fun smartcastInElse(/*0*/ x: kotlin.Any?): kotlin.Unit

compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/when/withSubjectNullableBoolean.kt

@@ -0,0 +1,55 @@
+// !LANGUAGE: +ReturnsEffect
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.internal.contracts.*
+
+fun safeIsString(x: Any?): Boolean? {
+    contract {
+        returns(true) implies (x is String)
+    }
+    return x?.let { it is String }
+}
+
+fun elseWithNullableResult(x: Any?) {
+    when (safeIsString(x)) {
+        false -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        else -> x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+
+    when (safeIsString(x)) {
+        true -> <!DEBUG_INFO_SMARTCAST!>x<!>.length
+        else -> x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+
+    when (safeIsString(x)) {
+        true -> <!DEBUG_INFO_SMARTCAST!>x<!>.length
+        false -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        else -> x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+
+    when (safeIsString(x)) {
+        true -> <!DEBUG_INFO_SMARTCAST!>x<!>.length
+        null -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        else -> x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+}
+
+fun exhaustiveWithNullableResult(x: Any?) {
+    when (safeIsString(x)) {
+        true -> <!DEBUG_INFO_SMARTCAST!>x<!>.length
+        false -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        null -> x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+
+    when (safeIsString(x)) {
+        false -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        true -> <!DEBUG_INFO_SMARTCAST!>x<!>.length
+        null -> x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+
+    when (safeIsString(x)) {
+        false -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        null -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        true -> <!DEBUG_INFO_SMARTCAST!>x<!>.length
+    }
+}

compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/when/withSubjectNullableBoolean.txt

@@ -0,0 +1,6 @@
+package
+
+public fun elseWithNullableResult(/*0*/ x: kotlin.Any?): kotlin.Unit
+public fun exhaustiveWithNullableResult(/*0*/ x: kotlin.Any?): kotlin.Unit
+public fun safeIsString(/*0*/ x: kotlin.Any?): kotlin.Boolean?
+    Returns(TRUE) -> x is String

compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/when/withoutSubject.kt

@@ -0,0 +1,30 @@
+// !LANGUAGE: +ReturnsEffect
+// !DIAGNOSTICS: -INVISIBLE_REFERENCE -INVISIBLE_MEMBER
+
+import kotlin.internal.contracts.*
+
+fun isString(x: Any?): Boolean {
+    contract {
+        returns(true) implies (x is String)
+    }
+    return x is String
+}
+
+fun exhaustive(x: Any?) {
+    when {
+        isString(x) -> <!DEBUG_INFO_SMARTCAST!>x<!>.length
+        !isString(x) -> x.<!UNRESOLVED_REFERENCE!>length<!>
+    }
+
+    when {
+        !isString(x) -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        isString(x) -> <!DEBUG_INFO_SMARTCAST!>x<!>.length
+    }
+}
+
+fun smartcastInElse(x: Any?) {
+    when {
+        !isString(x) -> x.<!UNRESOLVED_REFERENCE!>length<!>
+        else -> <!DEBUG_INFO_SMARTCAST!>x<!>.length
+    }
+}

compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/when/withoutSubject.txt

@@ -0,0 +1,7 @@
+package
+
+public fun exhaustive(/*0*/ x: kotlin.Any?): kotlin.Unit
+public fun isString(/*0*/ x: kotlin.Any?): kotlin.Boolean
+    Returns(TRUE) -> x is String
+
+public fun smartcastInElse(/*0*/ x: kotlin.Any?): kotlin.Unit