From 13eddba1f2fc64f7f34c4cf54b32cc6066a0c9ef Mon Sep 17 00:00:00 2001
From: Mikhail Zarechenskiy <mikhail.zarechenskiy@jetbrains.com>
Date: Wed, 5 Apr 2017 04:59:16 +0300
Subject: [PATCH] Fix false warning about useless cast in property and property
 accessor

Note that there are some other problems, for example:
`val a = if (true) 1 as Number else 2`, here we'll get useless cast

 #KT-9551 Fixed
 #KT-9645 Fixed
---
 .../BasicExpressionTypingVisitor.java           |  4 ++++
 compiler/testData/diagnostics/tests/Casts.kt    |  2 +-
 .../cast/AsInPropertyAndPropertyAccessor.kt     | 17 +++++++++++++++++
 .../cast/AsInPropertyAndPropertyAccessor.txt    |  6 ++++++
 .../diagnostics/tests/cast/AsTypeAlias.kt       |  2 +-
 .../tests/cast/bare/FromErrorType.kt            |  2 +-
 .../checkers/DiagnosticsTestGenerated.java      |  6 ++++++
 7 files changed, 36 insertions(+), 3 deletions(-)
 create mode 100644 compiler/testData/diagnostics/tests/cast/AsInPropertyAndPropertyAccessor.kt
 create mode 100644 compiler/testData/diagnostics/tests/cast/AsInPropertyAndPropertyAccessor.txt

diff --git a/compiler/frontend/src/org/jetbrains/kotlin/types/expressions/BasicExpressionTypingVisitor.java b/compiler/frontend/src/org/jetbrains/kotlin/types/expressions/BasicExpressionTypingVisitor.java
index 194aa8abe5f..0afb36cb513 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/types/expressions/BasicExpressionTypingVisitor.java
+++ b/compiler/frontend/src/org/jetbrains/kotlin/types/expressions/BasicExpressionTypingVisitor.java
@@ -445,6 +445,10 @@ public class BasicExpressionTypingVisitor extends ExpressionTypingVisitor {
         if (parent instanceof KtBinaryExpression || parent instanceof KtUnaryExpression) {
             return true;
         }
+        // Previously we've checked that there is no expected type, therefore cast in property has an effect on inference
+        if (parent instanceof KtProperty || parent instanceof KtPropertyAccessor) {
+            return true;
+        }
         return false;
     }
 
diff --git a/compiler/testData/diagnostics/tests/Casts.kt b/compiler/testData/diagnostics/tests/Casts.kt
index 7e320605db1..ce45e53f0ce 100644
--- a/compiler/testData/diagnostics/tests/Casts.kt
+++ b/compiler/testData/diagnostics/tests/Casts.kt
@@ -15,7 +15,7 @@ fun test() : Unit {
   checkSubtype<Int?>(x <!USELESS_CAST!>as? Int?<!>)
   checkSubtype<Int?>(y as? Int?)
 
-  val <!UNUSED_VARIABLE!>s<!> = "" <!USELESS_CAST!>as Any<!>
+  val <!UNUSED_VARIABLE!>s<!> = "" as Any
   ("" as String?)?.length
   (data@("" as String?))?.length
   (<!WRONG_ANNOTATION_TARGET!>@MustBeDocumented()<!>( "" as String?))?.length
diff --git a/compiler/testData/diagnostics/tests/cast/AsInPropertyAndPropertyAccessor.kt b/compiler/testData/diagnostics/tests/cast/AsInPropertyAndPropertyAccessor.kt
new file mode 100644
index 00000000000..426da743e89
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/AsInPropertyAndPropertyAccessor.kt
@@ -0,0 +1,17 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+fun test() {
+    val a = 1 as Any?
+    val b: Number = 1 <!USELESS_CAST!>as Number<!>
+    val c = null as String?
+    val d: Number = 1 <!USELESS_CAST!>as Int<!>
+}
+
+val c1 get() = 1 as Number
+val c2: Number get() = 1 <!USELESS_CAST!>as Number<!>
+
+val d: Number
+    get() {
+        1 <!USELESS_CAST!>as Number<!>
+        return 1 <!USELESS_CAST!>as Number<!>
+    }
\ No newline at end of file
diff --git a/compiler/testData/diagnostics/tests/cast/AsInPropertyAndPropertyAccessor.txt b/compiler/testData/diagnostics/tests/cast/AsInPropertyAndPropertyAccessor.txt
new file mode 100644
index 00000000000..1b5a3b0878f
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/cast/AsInPropertyAndPropertyAccessor.txt
@@ -0,0 +1,6 @@
+package
+
+public val c1: kotlin.Number
+public val c2: kotlin.Number
+public val d: kotlin.Number
+public fun test(): kotlin.Unit
diff --git a/compiler/testData/diagnostics/tests/cast/AsTypeAlias.kt b/compiler/testData/diagnostics/tests/cast/AsTypeAlias.kt
index 321302d7f8d..6ae90b849fb 100644
--- a/compiler/testData/diagnostics/tests/cast/AsTypeAlias.kt
+++ b/compiler/testData/diagnostics/tests/cast/AsTypeAlias.kt
@@ -1,7 +1,7 @@
 typealias MyString = String
 
 val x: MyString = ""
-val y = x <!USELESS_CAST!>as Any<!>
+val y = x as Any
 
 interface Base
 class Derived : Base
diff --git a/compiler/testData/diagnostics/tests/cast/bare/FromErrorType.kt b/compiler/testData/diagnostics/tests/cast/bare/FromErrorType.kt
index 0a76ce0445c..edb31389f1b 100644
--- a/compiler/testData/diagnostics/tests/cast/bare/FromErrorType.kt
+++ b/compiler/testData/diagnostics/tests/cast/bare/FromErrorType.kt
@@ -3,6 +3,6 @@
 class G<T>
 
 fun foo(p: <!UNRESOLVED_REFERENCE!>P<!>) {
-    val v = <!DEBUG_INFO_ELEMENT_WITH_ERROR_TYPE!>p<!> <!USELESS_CAST!>as <!NO_TYPE_ARGUMENTS_ON_RHS!>G?<!><!>
+    val v = <!DEBUG_INFO_ELEMENT_WITH_ERROR_TYPE!>p<!> as <!NO_TYPE_ARGUMENTS_ON_RHS!>G?<!>
     checkSubtype<G<*>>(v!!)
 }
\ No newline at end of file
diff --git a/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java b/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java
index d6e998c330b..976929a4ad5 100644
--- a/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java
+++ b/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java
@@ -2686,6 +2686,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("AsInPropertyAndPropertyAccessor.kt")
+            public void testAsInPropertyAndPropertyAccessor() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/cast/AsInPropertyAndPropertyAccessor.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("AsNothing.kt")
             public void testAsNothing() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/cast/AsNothing.kt");