FIR checker: warn unnecessary non-null assertions

compiler/testData/diagnostics/tests/smartCasts/elvis/basicOn.fir.kt

@@ -27,13 +27,13 @@ fun bar(o: Any) {
 
     }
     else {
-        order!!.doSomething()
+        order<!UNNECESSARY_NOT_NULL_ASSERTION!>!!<!>.doSomething()
     }
     if (order?.notExpired() ?: true) {
 
     }
     else {
-        order!!.doSomething()
+        order<!UNNECESSARY_NOT_NULL_ASSERTION!>!!<!>.doSomething()
     }
 }
 

compiler/testData/diagnostics/tests/smartCasts/inference/kt1355.fir.kt

@@ -25,7 +25,7 @@ public data class Tag(public var tagName: String) {
                 attributes.remove("id")
             }
             else {
-                attributes["id"] = value!!
+                attributes["id"] = value<!UNNECESSARY_NOT_NULL_ASSERTION!>!!<!>
                 attributes["id"] = value
             }
         }

compiler/testData/diagnostics/tests/smartCasts/inference/kt2851.fir.kt

@@ -5,7 +5,7 @@ fun main() {
     val value: String? = ""
     if (value != null) {
         foo(Pair("val", value))
-        foo(Pair("val", value!!))
+        foo(Pair("val", value<!UNNECESSARY_NOT_NULL_ASSERTION!>!!<!>))
         foo(Pair<String, String>("val", value))
     }
 }

compiler/testData/diagnostics/tests/smartCasts/kt2865.fir.kt

@@ -3,10 +3,10 @@ operator fun <K, V> MutableMap<K, V>.set(k: K, v: V) {}
 
 fun foo(a: MutableMap<String, String>, x: String?) {
     a[x!!] = x
-    a[x] = x!!
+    a[x] = x<!UNNECESSARY_NOT_NULL_ASSERTION!>!!<!>
 }
 
 fun foo1(a: MutableMap<String, String>, x: String?) {
     <!INAPPLICABLE_CANDIDATE!>a[x]<!> = x!!
-    a[x!!] = x
+    a[x<!UNNECESSARY_NOT_NULL_ASSERTION!>!!<!>] = x
 }

compiler/testData/diagnostics/tests/smartCasts/safecalls/argument.fir.kt

@@ -1,6 +0,0 @@
-fun calc(x: List<String>?): Int {
-    // After KT-5840 fix !! assertion should become unnecessary here
-    x?.get(x!!.size - 1)
-    // x?. or x!! above should not provide smart cast here
-    return x<!UNSAFE_CALL!>.<!>size
-}

compiler/testData/diagnostics/tests/smartCasts/safecalls/argument.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 fun calc(x: List<String>?): Int {
     // After KT-5840 fix !! assertion should become unnecessary here
     x?.get(x<!UNNECESSARY_NOT_NULL_ASSERTION!>!!<!>.size - 1)

compiler/testData/diagnostics/tests/smartCasts/safecalls/propertyChain.fir.kt

@@ -10,5 +10,5 @@ fun foo(y: MyClass?): Int {
 fun bar(y: MyClass?) {
     y?.x!!.length
     // !! is NOT necessary here, because y?.x != null
-    y!!.x
-}
+    y<!UNNECESSARY_NOT_NULL_ASSERTION!>!!<!>.x
+}