[FIR] Introduce unchecked not-null cast as internal operation for !!, ?:

compiler/fir/tree/src/org/jetbrains/kotlin/fir/FirRenderer.kt

@@ -919,4 +919,9 @@ class FirRenderer(builder: StringBuilder) : FirVisitorVoid() {
     override fun visitErrorExpression(errorExpression: FirErrorExpression) {
         print("ERROR_EXPR(${errorExpression.reason})")
     }
+
+    override fun visitUncheckedNotNullCast(uncheckedNotNullCast: FirUncheckedNotNullCast) {
+        uncheckedNotNullCast.expression.accept(this)
+        print("!")
+    }
 }

compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/FirUncheckedNotNullCast.kt

@@ -0,0 +1,14 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.fir.expressions
+
+import org.jetbrains.kotlin.fir.visitors.FirVisitor
+
+interface FirUncheckedNotNullCast : FirCall {
+    override fun <R, D> accept(visitor: FirVisitor<R, D>, data: D): R = visitor.visitUncheckedNotNullCast(this, data)
+
+    val expression: FirExpression get() = arguments[0]
+}

compiler/fir/tree/src/org/jetbrains/kotlin/fir/expressions/impl/FirUncheckedNotNullCastImpl.kt

@@ -0,0 +1,24 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.fir.expressions.impl
+
+import com.intellij.psi.PsiElement
+import org.jetbrains.kotlin.fir.FirSession
+import org.jetbrains.kotlin.fir.expressions.FirExpression
+import org.jetbrains.kotlin.fir.expressions.FirUncheckedNotNullCast
+import org.jetbrains.kotlin.fir.expressions.FirOperation
+import org.jetbrains.kotlin.fir.types.FirTypeRef
+
+class FirUncheckedNotNullCastImpl(
+    session: FirSession,
+    psi: PsiElement?,
+    expression: FirExpression
+) : FirAbstractCall(session, psi), FirUncheckedNotNullCast {
+    init {
+        arguments += expression
+    }
+}
+

compiler/fir/tree/visitors/org/jetbrains/kotlin/fir/visitors/FirTransformerGenerated.kt

@@ -236,6 +236,10 @@ abstract class FirTransformer<in D> : FirVisitor<CompositeTransformResult<FirEle
         return transformCall(stringConcatenationCall, data)
     }
 
+    open fun transformUncheckedNotNullCast(uncheckedNotNullCast: FirUncheckedNotNullCast, data: D): CompositeTransformResult<FirStatement> {
+        return transformCall(uncheckedNotNullCast, data)
+    }
+
     open fun transformClassReferenceExpression(classReferenceExpression: FirClassReferenceExpression, data: D): CompositeTransformResult<FirStatement> {
         return transformExpression(classReferenceExpression, data)
     }
@@ -732,6 +736,10 @@ abstract class FirTransformer<in D> : FirVisitor<CompositeTransformResult<FirEle
         return transformTypedDeclaration(typedDeclaration, data)
     }
 
+    final override fun visitUncheckedNotNullCast(uncheckedNotNullCast: FirUncheckedNotNullCast, data: D): CompositeTransformResult<FirElement> {
+        return transformUncheckedNotNullCast(uncheckedNotNullCast, data)
+    }
+
     final override fun visitUserTypeRef(userTypeRef: FirUserTypeRef, data: D): CompositeTransformResult<FirElement> {
         return transformUserTypeRef(userTypeRef, data)
     }

compiler/fir/tree/visitors/org/jetbrains/kotlin/fir/visitors/FirVisitorGenerated.kt

@@ -236,6 +236,10 @@ abstract class FirVisitor<out R, in D> {
         return visitCall(stringConcatenationCall, data)
     }
 
+    open fun visitUncheckedNotNullCast(uncheckedNotNullCast: FirUncheckedNotNullCast, data: D): R {
+        return visitCall(uncheckedNotNullCast, data)
+    }
+
     open fun visitClassReferenceExpression(classReferenceExpression: FirClassReferenceExpression, data: D): R {
         return visitExpression(classReferenceExpression, data)
     }

compiler/fir/tree/visitors/org/jetbrains/kotlin/fir/visitors/FirVisitorVoidGenerated.kt

@@ -236,6 +236,10 @@ abstract class FirVisitorVoid : FirVisitor<Unit, Nothing?>() {
         visitCall(stringConcatenationCall, null)
     }
 
+    open fun visitUncheckedNotNullCast(uncheckedNotNullCast: FirUncheckedNotNullCast) {
+        visitCall(uncheckedNotNullCast, null)
+    }
+
     open fun visitClassReferenceExpression(classReferenceExpression: FirClassReferenceExpression) {
         visitExpression(classReferenceExpression, null)
     }
@@ -732,6 +736,10 @@ abstract class FirVisitorVoid : FirVisitor<Unit, Nothing?>() {
         visitTypedDeclaration(typedDeclaration)
     }
 
+    final override fun visitUncheckedNotNullCast(uncheckedNotNullCast: FirUncheckedNotNullCast, data: Nothing?) {
+        visitUncheckedNotNullCast(uncheckedNotNullCast)
+    }
+
     final override fun visitUserTypeRef(userTypeRef: FirUserTypeRef, data: Nothing?) {
         visitUserTypeRef(userTypeRef)
     }