From f19ede0637ea97db3f3a4f8f07626abd8f232e52 Mon Sep 17 00:00:00 2001
From: Alexander Udalov <Alexander.Udalov@jetbrains.com>
Date: Wed, 4 Dec 2013 19:13:39 +0400
Subject: [PATCH] Don't treat values of type "Unit?" to be always equal to
 Unit.VALUE

Two changes here: StackValue.Constant does cast iff value is non-null (if null,
no cast between classes is really needed, as null can be an instance of
anything), and codegen for safe qualified expressions uses correct type for the
expression

 #KT-4265 Fixed
---
 .../jet/codegen/ExpressionCodegen.java        |  3 +--
 .../org/jetbrains/jet/codegen/StackValue.java |  5 ++++-
 compiler/testData/codegen/box/unit/kt4265.kt  | 14 +++++++++++++
 .../testData/codegen/box/unit/nullableUnit.kt | 20 +++++++++++++++++++
 .../BlackBoxCodegenTestGenerated.java         | 10 ++++++++++
 5 files changed, 49 insertions(+), 3 deletions(-)
 create mode 100644 compiler/testData/codegen/box/unit/kt4265.kt
 create mode 100644 compiler/testData/codegen/box/unit/nullableUnit.kt

diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/ExpressionCodegen.java b/compiler/backend/src/org/jetbrains/jet/codegen/ExpressionCodegen.java
index b765d1ce7f0..f7649be6416 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/ExpressionCodegen.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/ExpressionCodegen.java
@@ -2622,13 +2622,13 @@ public class ExpressionCodegen extends JetVisitor<StackValue, StackValue> implem
     public StackValue visitSafeQualifiedExpression(@NotNull JetSafeQualifiedExpression expression, StackValue unused) {
         JetExpression receiver = expression.getReceiverExpression();
         JetExpression selector = expression.getSelectorExpression();
+        Type type = boxType(expressionType(expression));
         Type receiverType = expressionType(receiver);
 
         gen(receiver, receiverType);
 
         if (isPrimitive(receiverType)) {
             StackValue propValue = genQualified(StackValue.onStack(receiverType), selector);
-            Type type = boxType(propValue.type);
             propValue.put(type, v);
 
             return StackValue.onStack(type);
@@ -2639,7 +2639,6 @@ public class ExpressionCodegen extends JetVisitor<StackValue, StackValue> implem
         v.dup();
         v.ifnull(ifnull);
         StackValue propValue = genQualified(StackValue.onStack(receiverType), selector);
-        Type type = boxType(propValue.type);
         propValue.put(type, v);
         v.goTo(end);
 
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/StackValue.java b/compiler/backend/src/org/jetbrains/jet/codegen/StackValue.java
index 4d02fd2749d..c69abf2286f 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/StackValue.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/StackValue.java
@@ -430,7 +430,10 @@ public abstract class StackValue {
             else {
                 v.aconst(value);
             }
-            coerceTo(type, v);
+
+            if (value != null) {
+                coerceTo(type, v);
+            }
         }
 
         @Override
diff --git a/compiler/testData/codegen/box/unit/kt4265.kt b/compiler/testData/codegen/box/unit/kt4265.kt
new file mode 100644
index 00000000000..3c1aaf9d462
--- /dev/null
+++ b/compiler/testData/codegen/box/unit/kt4265.kt
@@ -0,0 +1,14 @@
+fun <T : Any, R> T.let(f: (T) -> R): R = f(this)
+
+fun box(): String {
+    val o: String? = null
+
+    var state = 0
+
+    o?.let {
+        state = 1
+    } ?: ({ state = 2 })()
+
+    if (state != 2) return "Fail: $state"
+    return "OK"
+}
diff --git a/compiler/testData/codegen/box/unit/nullableUnit.kt b/compiler/testData/codegen/box/unit/nullableUnit.kt
new file mode 100644
index 00000000000..12abddc9695
--- /dev/null
+++ b/compiler/testData/codegen/box/unit/nullableUnit.kt
@@ -0,0 +1,20 @@
+fun isNull(x: Unit?) = x == null
+
+fun isNullGeneric<T : Any>(x: T?) = x == null
+
+fun deepIsNull0(x: Unit?) = isNull(x)
+fun deepIsNull(x: Unit?) = deepIsNull0(x)
+
+fun box(): String {
+    if (!isNull(null)) return "Fail 1"
+
+    val x: Unit? = null
+    if (!isNull(x)) return "Fail 2"
+
+    val y = x
+    if (!isNullGeneric(y)) return "Fail 3"
+
+    if (!deepIsNull((null : Unit?) ?: null)) return "Fail 4"
+
+    return "OK"
+}
diff --git a/compiler/tests/org/jetbrains/jet/codegen/generated/BlackBoxCodegenTestGenerated.java b/compiler/tests/org/jetbrains/jet/codegen/generated/BlackBoxCodegenTestGenerated.java
index 50db654cffc..8b07fd0f152 100644
--- a/compiler/tests/org/jetbrains/jet/codegen/generated/BlackBoxCodegenTestGenerated.java
+++ b/compiler/tests/org/jetbrains/jet/codegen/generated/BlackBoxCodegenTestGenerated.java
@@ -4764,6 +4764,16 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), "org.jetbrains.jet.generators.tests.GenerateTests", new File("compiler/testData/codegen/box/unit"), Pattern.compile("^(.+)\\.kt$"), true);
         }
         
+        @TestMetadata("kt4265.kt")
+        public void testKt4265() throws Exception {
+            doTest("compiler/testData/codegen/box/unit/kt4265.kt");
+        }
+        
+        @TestMetadata("nullableUnit.kt")
+        public void testNullableUnit() throws Exception {
+            doTest("compiler/testData/codegen/box/unit/nullableUnit.kt");
+        }
+        
         @TestMetadata("unitClassObject.kt")
         public void testUnitClassObject() throws Exception {
             doTest("compiler/testData/codegen/box/unit/unitClassObject.kt");