FIR checker: differentiate UNSAFE_CALL from INAPPLICABLE_CANDIDATE

To do so, inside the root cause of inapplicable candidate errors,
we will record expected/actual type of receiver, if any.
That will help identifying inapplicable calls on nullable receiver.

compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/isNullOrBlank.fir.kt

@@ -3,7 +3,7 @@
 
 fun testIsNullOrBlank(x: String?) {
     if (x.isNullOrBlank()) {
-        x.<!INAPPLICABLE_CANDIDATE!>length<!>
+        x.<!UNSAFE_CALL!>length<!>
     }
     else {
         x.length
@@ -15,6 +15,6 @@ fun testIsNotNullOrBlank(x: String?) {
         x.length
     }
 
-    x.<!INAPPLICABLE_CANDIDATE!>length<!>
+    x.<!UNSAFE_CALL!>length<!>
 }
 

compiler/testData/diagnostics/testsWithStdLib/contracts/fromStdlib/isNullOrEmpty.fir.kt

@@ -3,7 +3,7 @@
 
 fun testIsNullOrEmpty(x: String?) {
     if (x.isNullOrEmpty()) {
-        x.<!INAPPLICABLE_CANDIDATE!>length<!>
+        x.<!UNSAFE_CALL!>length<!>
     }
     else {
         x.length
@@ -15,6 +15,6 @@ fun testIsNotNullOrEmpty(x: String?) {
         x.length
     }
 
-    x.<!INAPPLICABLE_CANDIDATE!>length<!>
+    x.<!UNSAFE_CALL!>length<!>
 }
 

compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/extensionReceiver.fir.kt

@@ -17,7 +17,7 @@ fun CharSequence?.isNullOrEmpty(): Boolean {
 fun smartcastOnReceiver(s: String?) {
     with(s) {
         if (isNullOrEmpty()) {
-            <!INAPPLICABLE_CANDIDATE!>length<!>
+            <!UNSAFE_CALL!>length<!>
         }
         else {
             length
@@ -32,7 +32,7 @@ fun mixedReceiver(s: String?) {
         }
     } else {
         with(s) {
-            <!INAPPLICABLE_CANDIDATE!>length<!>
+            <!UNSAFE_CALL!>length<!>
         }
     }
 }

compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/extensionReceiver_after.fir.kt

@@ -17,7 +17,7 @@ fun CharSequence?.isNullOrEmpty(): Boolean {
 fun smartcastOnReceiver(s: String?) {
     with(s) {
         if (isNullOrEmpty()) {
-            <!INAPPLICABLE_CANDIDATE!>length<!>
+            <!UNSAFE_CALL!>length<!>
         }
         else {
             length
@@ -32,7 +32,7 @@ fun mixedReceiver(s: String?) {
         }
     } else {
         with(s) {
-            <!INAPPLICABLE_CANDIDATE!>length<!>
+            <!UNSAFE_CALL!>length<!>
         }
     }
 }

compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/nullabilitySmartcastWhenNullability.fir.kt

@@ -14,7 +14,7 @@ fun nullWhenNull(x: Int?): Int? {
 
 fun testNullWhenNull(x: Int?) {
     if (nullWhenNull(x) == null) {
-        x.<!INAPPLICABLE_CANDIDATE!>dec<!>()
+        x.<!UNSAFE_CALL!>dec<!>()
     }
     else {
         x.dec()
@@ -24,10 +24,10 @@ fun testNullWhenNull(x: Int?) {
         x.dec()
     }
     else {
-        x.<!INAPPLICABLE_CANDIDATE!>dec<!>()
+        x.<!UNSAFE_CALL!>dec<!>()
     }
 
-    x.<!INAPPLICABLE_CANDIDATE!>dec<!>()
+    x.<!UNSAFE_CALL!>dec<!>()
 }
 
 // NB. it is the same function as `nullWhenNull`, but annotations specifies other facet of the function behaviour
@@ -43,15 +43,15 @@ fun testNotNullWhenNotNull (x: Int?) {
         x == null
     }
     else {
-        x.<!INAPPLICABLE_CANDIDATE!>dec<!>()
+        x.<!UNSAFE_CALL!>dec<!>()
     }
 
     if (notNullWhenNotNull(x) != null) {
-        x.<!INAPPLICABLE_CANDIDATE!>dec<!>()
+        x.<!UNSAFE_CALL!>dec<!>()
     }
     else {
         x == null
     }
 
-    x.<!INAPPLICABLE_CANDIDATE!>dec<!>()
+    x.<!UNSAFE_CALL!>dec<!>()
 }

compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/operatorsTests/equalsOperator.fir.kt

@@ -20,28 +20,28 @@ fun myEqualsNotNull(x: Int?): Boolean {
 }
 
 fun testBasicEquals(x: Int?) {
-    x.<!INAPPLICABLE_CANDIDATE!>inc<!>()
+    x.<!UNSAFE_CALL!>inc<!>()
 
     if (myEqualsNull(x)) {
-        x.<!INAPPLICABLE_CANDIDATE!>inc<!>()
+        x.<!UNSAFE_CALL!>inc<!>()
     }
     else {
         x.inc()
     }
 
-    x.<!INAPPLICABLE_CANDIDATE!>inc<!>()
+    x.<!UNSAFE_CALL!>inc<!>()
 }
 
 fun testBasicNotEquals(x: Int?) {
-    x.<!INAPPLICABLE_CANDIDATE!>inc<!>()
+    x.<!UNSAFE_CALL!>inc<!>()
 
     if (myEqualsNotNull(x)) {
         x.inc()
     }
     else {
-        x.<!INAPPLICABLE_CANDIDATE!>inc<!>()
+        x.<!UNSAFE_CALL!>inc<!>()
     }
 
-    x.<!INAPPLICABLE_CANDIDATE!>inc<!>()
+    x.<!UNSAFE_CALL!>inc<!>()
 }
 

compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/receiver.fir.kt

@@ -14,7 +14,7 @@ fun Any?.isNull(): Boolean {
 
 fun smartcastOnReceiver(x: Int?) {
     if (x.isNull()) {
-        x.<!INAPPLICABLE_CANDIDATE!>inc<!>()
+        x.<!UNSAFE_CALL!>inc<!>()
     }
     else {
         x.dec()
@@ -26,10 +26,10 @@ class UnstableReceiver {
 
     fun smartcastOnUnstableReceiver() {
         if (x.isNull()) {
-            x.<!INAPPLICABLE_CANDIDATE!>inc<!>()
+            x.<!UNSAFE_CALL!>inc<!>()
         }
         else {
-            x.<!INAPPLICABLE_CANDIDATE!>dec<!>()
+            x.<!UNSAFE_CALL!>dec<!>()
         }
     }
 }

compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/valueOfContractedFunctionIngored.fir.kt

@@ -6,6 +6,6 @@ import kotlin.contracts.*
 
 fun f3(value: String?) {
     if (!value.isNullOrEmpty() is Boolean) {
-        value.<!INAPPLICABLE_CANDIDATE!>length<!>
+        value.<!UNSAFE_CALL!>length<!>
     }
 }