From 15c83abfd89db32fdb6d1f01fcb7c4ba7e8ffc9a Mon Sep 17 00:00:00 2001
From: Ivan Kochurkin <ivan.kochurkin@jetbrains.com>
Date: Thu, 11 Nov 2021 19:13:05 +0300
Subject: [PATCH] [FIR] Throw UNCHECKED_CAST instead of
 NO_TYPE_ARGUMENTS_ON_RHS closer to FE 1.0

---
 .../resolve/FirExpressionsResolveTransformer.kt  | 16 ++++++++++------
 .../capturedParameters/uncheckedCast.fir.kt      |  4 ++--
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/body/resolve/FirExpressionsResolveTransformer.kt b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/body/resolve/FirExpressionsResolveTransformer.kt
index 6b787020c32..6321e4017a4 100644
--- a/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/body/resolve/FirExpressionsResolveTransformer.kt
+++ b/compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/body/resolve/FirExpressionsResolveTransformer.kt
@@ -10,6 +10,7 @@ import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.fakeElement
 import org.jetbrains.kotlin.fir.*
 import org.jetbrains.kotlin.fir.declarations.*
+import org.jetbrains.kotlin.fir.declarations.utils.isLocal
 import org.jetbrains.kotlin.fir.diagnostics.*
 import org.jetbrains.kotlin.fir.expressions.*
 import org.jetbrains.kotlin.fir.expressions.builder.buildErrorExpression
@@ -603,7 +604,7 @@ open class FirExpressionsResolveTransformer(transformer: FirBodyResolveTransform
         override fun <T> shouldRunCompletion(call: T): Boolean where T : FirStatement, T : FirResolvable = false
     }
 
-    private fun FirTypeRef.withTypeArgumentsForBareType(argument: FirExpression): FirTypeRef {
+    private fun FirTypeRef.withTypeArgumentsForBareType(argument: FirExpression, operation: FirOperation): FirTypeRef {
         val type = coneTypeSafe<ConeClassLikeType>() ?: return this
         if (type.typeArguments.isNotEmpty()) return this
 
@@ -611,10 +612,13 @@ open class FirExpressionsResolveTransformer(transformer: FirBodyResolveTransform
         if (firClass.typeParameters.isEmpty()) return this
 
         val originalType = argument.unwrapSmartcastExpression().typeRef.coneTypeSafe<ConeKotlinType>() ?: return this
-        val newType = components.computeRepresentativeTypeForBareType(type, originalType) ?: return buildErrorTypeRef {
-            source = this@withTypeArgumentsForBareType.source
-            diagnostic = ConeNoTypeArgumentsOnRhsError(firClass.typeParameters.size, firClass.symbol)
-        }
+        val newType = components.computeRepresentativeTypeForBareType(type, originalType)
+            ?: if (firClass.isLocal && (operation == FirOperation.AS || operation == FirOperation.SAFE_AS)) {
+                (firClass as FirClass).defaultType()
+            } else return buildErrorTypeRef {
+                source = this@withTypeArgumentsForBareType.source
+                diagnostic = ConeNoTypeArgumentsOnRhsError(firClass.typeParameters.size, firClass.symbol)
+            }
         return if (newType.typeArguments.isEmpty()) this else withReplacedConeType(newType)
     }
 
@@ -632,7 +636,7 @@ open class FirExpressionsResolveTransformer(transformer: FirBodyResolveTransform
             }
         }.transformTypeOperatorCallChildren()
 
-        val conversionTypeRef = resolved.conversionTypeRef.withTypeArgumentsForBareType(resolved.argument)
+        val conversionTypeRef = resolved.conversionTypeRef.withTypeArgumentsForBareType(resolved.argument, typeOperatorCall.operation)
         resolved.transformChildren(object : FirDefaultTransformer<Any?>() {
             override fun <E : FirElement> transformElement(element: E, data: Any?): E {
                 return element
diff --git a/compiler/testData/diagnostics/tests/generics/capturedParameters/uncheckedCast.fir.kt b/compiler/testData/diagnostics/tests/generics/capturedParameters/uncheckedCast.fir.kt
index 1c0cb0eec96..6d7618c501e 100644
--- a/compiler/testData/diagnostics/tests/generics/capturedParameters/uncheckedCast.fir.kt
+++ b/compiler/testData/diagnostics/tests/generics/capturedParameters/uncheckedCast.fir.kt
@@ -6,11 +6,11 @@ fun <E> foo(x: Any, y: Any) : Any {
     }
 
     if (1 == 2) {
-        x as <!NO_TYPE_ARGUMENTS_ON_RHS!>C<!>
+        x <!UNCHECKED_CAST!>as C<!>
     }
 
     if (2 == 3) {
-        x as? <!NO_TYPE_ARGUMENTS_ON_RHS, NO_TYPE_ARGUMENTS_ON_RHS!>C<!>
+        x <!UNCHECKED_CAST!>as? C<!>
     }
 
     class Outer<F> {