From ac0db5ce807b6637326f89edb74e7f630594f8b0 Mon Sep 17 00:00:00 2001
From: Alexander Udalov <Alexander.Udalov@jetbrains.com>
Date: Sat, 4 Jul 2015 03:18:50 +0300
Subject: [PATCH] Fix incorrect TypeCastException message when casting null

 #KT-5121 Fixed
---
 .../kotlin/codegen/ExpressionCodegen.java     |  7 ++-----
 .../regressions/typeCastException.kt          | 20 ++++++++++++++++---
 2 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/compiler/backend/src/org/jetbrains/kotlin/codegen/ExpressionCodegen.java b/compiler/backend/src/org/jetbrains/kotlin/codegen/ExpressionCodegen.java
index 47dc409c800..99be45477c4 100644
--- a/compiler/backend/src/org/jetbrains/kotlin/codegen/ExpressionCodegen.java
+++ b/compiler/backend/src/org/jetbrains/kotlin/codegen/ExpressionCodegen.java
@@ -3727,7 +3727,7 @@ The "returned" value of try expression with no finally is either the last expres
 
     @Override
     public StackValue visitBinaryWithTypeRHSExpression(@NotNull JetBinaryExpressionWithTypeRHS expression, StackValue receiver) {
-        final JetExpression left = expression.getLeft();
+        JetExpression left = expression.getLeft();
         final IElementType opToken = expression.getOperationReference().getReferencedNameElementType();
         if (opToken == JetTokens.COLON) {
             return gen(left);
@@ -3752,10 +3752,7 @@ The "returned" value of try expression with no finally is either the last expres
                         v.dup();
                         Label nonnull = new Label();
                         v.ifnonnull(nonnull);
-                        JetType leftType = bindingContext.getType(left);
-                        assert leftType != null;
-                        genThrow(v, "kotlin/TypeCastException", DescriptorRenderer.FQ_NAMES_IN_TYPES.renderType(leftType) +
-                                                                " cannot be cast to " +
+                        genThrow(v, "kotlin/TypeCastException", "null cannot be cast to non-null type " +
                                                                 DescriptorRenderer.FQ_NAMES_IN_TYPES.renderType(rightType));
                         v.mark(nonnull);
                     }
diff --git a/compiler/testData/codegen/boxWithStdlib/regressions/typeCastException.kt b/compiler/testData/codegen/boxWithStdlib/regressions/typeCastException.kt
index e67ff8472d5..5a25780bb51 100644
--- a/compiler/testData/codegen/boxWithStdlib/regressions/typeCastException.kt
+++ b/compiler/testData/codegen/boxWithStdlib/regressions/typeCastException.kt
@@ -1,4 +1,7 @@
+import java.util.ArrayList
+
 // KT-2823 TypeCastException has no message
+// KT-5121 Better error message in on casting null to non-null type
 
 fun box(): String {
     try {
@@ -6,9 +9,20 @@ fun box(): String {
         a as Array<String>
     }
     catch (e: TypeCastException) {
-        if (e.getMessage() == "kotlin.Any? cannot be cast to kotlin.Array<kotlin.String>") {
-            return "OK"
+        if (e.getMessage() != "null cannot be cast to non-null type kotlin.Array<kotlin.String>") {
+            return "Fail 1: $e"
         }
     }
-    return "fail"
+
+    try {
+        val x: String? = null
+        x as String
+    }
+    catch (e: TypeCastException) {
+        if (e.getMessage() != "null cannot be cast to non-null type kotlin.String") {
+            return "Fail 2: $e"
+        }
+    }
+
+    return "OK"
 }