[NI] Soften restictions on using Nothing as proper constraint for full call completion

Consider lower `Nothing` constraint non-proper only if there is a dependant not analyzed postponed atom.
Early completion to `Nothing` provides data flow info for smart casts.

KT-35668 Fixed

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

@@ -15,7 +15,7 @@ val ww = if (true) {
     <!OI;TYPE_MISMATCH!>{ true }<!> <!USELESS_ELVIS!>?: null!!<!>
 }
 else if (true) {
-    <!NI;TYPE_MISMATCH, NI;TYPE_MISMATCH, TYPE_MISMATCH!>{ <!NI;CONSTANT_EXPECTED_TYPE_MISMATCH!>true<!> }<!> <!USELESS_ELVIS!>?: null!!<!>
+    <!OI;TYPE_MISMATCH!>{ true }<!> <!USELESS_ELVIS!>?: null!!<!>
 }
 else {
     null!!

compiler/testData/diagnostics/tests/inference/completion/lambdaWithVariableAndNothing.fir.kt

@@ -0,0 +1,52 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun <K> id(it: K) = it
+
+fun <E> smartCast(arg: E?, fn: () -> Any?): E = TODO()
+fun <E1> noSmartCast1(arg: E1?, fn: () -> E1): E1 = TODO()
+fun <E2> noSmartCast2(arg: E2?, fn: E2): E2 = TODO()
+fun <E3, F : E3> noSmartCast3(arg: E3?, fn: () -> F): E3 = TODO()
+fun <E4, F : E4> noSmartCast4(arg: E4?, fn: F): E4 = TODO()
+
+
+fun testSmartCast(s: String?) {
+    id(
+        if (s != null) ""
+        else smartCast(null) { "" }
+    )
+    s.length
+}
+
+fun testNoSmartCast1(s: String?) {
+    id(
+        if (s != null) ""
+        else noSmartCast1(null) { "" }
+    )
+    s.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
+
+fun testNoSmartCast2(s: String?) {
+    id(
+        if (s != null) ( {""} )
+        else noSmartCast2(null) { "" }
+    )
+    s.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
+
+fun testNoSmartCast3(s: String?) {
+    id(
+        if (s != null) ""
+        else noSmartCast3(null) { "" }
+    )
+    s.<!INAPPLICABLE_CANDIDATE!>length<!>
+}
+
+// KT-36069
+fun testNoSmartCast4(s: String?) {
+    id(
+        if (s != null) ( {""} )
+        else noSmartCast4(null) { "" }
+    )
+    s.<!INAPPLICABLE_CANDIDATE!>length<!>
+}

compiler/testData/diagnostics/tests/inference/completion/lambdaWithVariableAndNothing.kt

@@ -0,0 +1,52 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun <K> id(it: K) = it
+
+fun <E> smartCast(arg: E?, fn: () -> Any?): E = TODO()
+fun <E1> noSmartCast1(arg: E1?, fn: () -> E1): E1 = TODO()
+fun <E2> noSmartCast2(arg: E2?, fn: E2): E2 = TODO()
+fun <E3, F : E3> noSmartCast3(arg: E3?, fn: () -> F): E3 = TODO()
+fun <E4, F : E4> noSmartCast4(arg: E4?, fn: F): E4 = TODO()
+
+
+fun testSmartCast(s: String?) {
+    id(
+        if (s != null) ""
+        else <!IMPLICIT_NOTHING_AS_TYPE_PARAMETER!>smartCast<!>(null) { "" }
+    )
+    <!DEBUG_INFO_SMARTCAST!>s<!>.length
+}
+
+fun testNoSmartCast1(s: String?) {
+    id(
+        if (s != null) ""
+        else noSmartCast1(null) { "" }
+    )
+    s<!UNSAFE_CALL!>.<!>length
+}
+
+fun testNoSmartCast2(s: String?) {
+    id(
+        if (s != null) ( {""} )
+        else noSmartCast2(null) { "" }
+    )
+    s<!UNSAFE_CALL!>.<!>length
+}
+
+fun testNoSmartCast3(s: String?) {
+    id(
+        if (s != null) ""
+        else noSmartCast3(null) { "" }
+    )
+    s<!UNSAFE_CALL!>.<!>length
+}
+
+// KT-36069
+fun testNoSmartCast4(s: String?) {
+    id(
+        if (s != null) ( {""} )
+        else <!IMPLICIT_NOTHING_AS_TYPE_PARAMETER, IMPLICIT_NOTHING_AS_TYPE_PARAMETER!>noSmartCast4<!>(null) <!TYPE_MISMATCH!>{ <!TYPE_MISMATCH!>""<!> }<!>
+    )
+    s<!UNSAFE_CALL!>.<!>length
+}

compiler/testData/diagnostics/tests/inference/completion/lambdaWithVariableAndNothing.txt

@@ -0,0 +1,13 @@
+package
+
+public fun </*0*/ K> id(/*0*/ it: K): K
+public fun </*0*/ E1> noSmartCast1(/*0*/ arg: E1?, /*1*/ fn: () -> E1): E1
+public fun </*0*/ E2> noSmartCast2(/*0*/ arg: E2?, /*1*/ fn: E2): E2
+public fun </*0*/ E3, /*1*/ F : E3> noSmartCast3(/*0*/ arg: E3?, /*1*/ fn: () -> F): E3
+public fun </*0*/ E4, /*1*/ F : E4> noSmartCast4(/*0*/ arg: E4?, /*1*/ fn: F): E4
+public fun </*0*/ E> smartCast(/*0*/ arg: E?, /*1*/ fn: () -> kotlin.Any?): E
+public fun testNoSmartCast1(/*0*/ s: kotlin.String?): kotlin.Unit
+public fun testNoSmartCast2(/*0*/ s: kotlin.String?): kotlin.Unit
+public fun testNoSmartCast3(/*0*/ s: kotlin.String?): kotlin.Unit
+public fun testNoSmartCast4(/*0*/ s: kotlin.String?): kotlin.Unit
+public fun testSmartCast(/*0*/ s: kotlin.String?): kotlin.Unit

compiler/testData/diagnostics/tests/regressions/kt35668.fir.kt

@@ -0,0 +1,20 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun main() {
+    val baseDir: String? = ""
+    val networkParameters: String? = ""
+    if (baseDir != null) {
+        if (networkParameters != null) {
+            Unit
+        } else if (true){
+            return
+        } else {
+            return
+        }
+    } else {
+        return
+    }
+
+    networkParameters.length // unsafe call
+}

compiler/testData/diagnostics/tests/regressions/kt35668.kt

@@ -0,0 +1,20 @@
+// !LANGUAGE: +NewInference
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+fun main() {
+    val baseDir: String? = ""
+    val networkParameters: String? = ""
+    if (baseDir != null) {
+        if (networkParameters != null) {
+            Unit
+        } else if (true){
+            return
+        } else {
+            return
+        }
+    } else {
+        return
+    }
+
+    <!DEBUG_INFO_SMARTCAST!>networkParameters<!>.length // unsafe call
+}

compiler/testData/diagnostics/tests/regressions/kt35668.txt

@@ -0,0 +1,3 @@
+package
+
+public fun main(): kotlin.Unit

compiler/testData/diagnostics/tests/when/kt9929.kt

@@ -1,5 +1,5 @@
 // !WITH_NEW_INFERENCE
-val test: Int = <!NI;TYPE_MISMATCH, NI;TYPE_MISMATCH, NI;TYPE_MISMATCH!>if (true) {
+val test: Int = <!NI;TYPE_MISMATCH, NI;TYPE_MISMATCH!>if (true) {
     when (2) {
         1 -> 1
         else -> <!OI;NULL_FOR_NONNULL_TYPE!>null<!>