From 96a7febd09f94a58530ff6ba3a0303737abbafa0 Mon Sep 17 00:00:00 2001
From: Mikhail Glukhikh <Mikhail.Glukhikh@jetbrains.com>
Date: Tue, 1 Mar 2016 17:10:15 +0300
Subject: [PATCH] Smart cast is performed now inside 'x as? Type ?: return'
 safe as / elvis combination #KT-10992 Fixed

---
 .../BasicExpressionTypingVisitor.java         | 24 +++++++++++++++++++
 .../diagnostics/tests/smartCasts/safeAs.kt    | 17 +++++++++++++
 .../diagnostics/tests/smartCasts/safeAs.txt   |  5 ++++
 .../checkers/DiagnosticsTestGenerated.java    |  6 +++++
 4 files changed, 52 insertions(+)
 create mode 100644 compiler/testData/diagnostics/tests/smartCasts/safeAs.kt
 create mode 100644 compiler/testData/diagnostics/tests/smartCasts/safeAs.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 50a1a7c4c5e..59752209134 100644
--- a/compiler/frontend/src/org/jetbrains/kotlin/types/expressions/BasicExpressionTypingVisitor.java
+++ b/compiler/frontend/src/org/jetbrains/kotlin/types/expressions/BasicExpressionTypingVisitor.java
@@ -1304,6 +1304,9 @@ public class BasicExpressionTypingVisitor extends ExpressionTypingVisitor {
             // left argument is considered not-null if it's not-null also in right part or if we have jump in right part
             if (jumpInRight || !rightDataFlowInfo.getPredictableNullability(leftValue).canBeNull()) {
                 dataFlowInfo = dataFlowInfo.disequate(leftValue, nullValue);
+                if (left instanceof KtBinaryExpressionWithTypeRHS) {
+                    dataFlowInfo = establishSubtypingForTypeRHS((KtBinaryExpressionWithTypeRHS) left, dataFlowInfo, context);
+                }
             }
             DataFlowValue resultValue = DataFlowValueFactory.createDataFlowValue(expression, type, context);
             dataFlowInfo = dataFlowInfo.assign(resultValue, leftValue).disequate(resultValue, nullValue);
@@ -1331,6 +1334,27 @@ public class BasicExpressionTypingVisitor extends ExpressionTypingVisitor {
                                                 context.dataFlowInfo);
     }
 
+    @NotNull
+    private static DataFlowInfo establishSubtypingForTypeRHS(
+            @NotNull KtBinaryExpressionWithTypeRHS left,
+            @NotNull DataFlowInfo dataFlowInfo,
+            @NotNull ExpressionTypingContext context
+    ) {
+        IElementType operationType = left.getOperationReference().getReferencedNameElementType();
+        if (operationType == AS_SAFE) {
+            KtExpression underSafeAs = left.getLeft();
+            KotlinType underSafeAsType = context.trace.getType(underSafeAs);
+            if (underSafeAsType != null) {
+                DataFlowValue underSafeAsValue = createDataFlowValue(underSafeAs, underSafeAsType, context);
+                KotlinType targetType = context.trace.get(BindingContext.TYPE, left.getRight());
+                if (targetType != null) {
+                    return dataFlowInfo.establishSubtyping(underSafeAsValue, targetType);
+                }
+            }
+        }
+        return dataFlowInfo;
+    }
+
     @NotNull
     public KotlinTypeInfo checkInExpression(
             @NotNull KtElement callElement,
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safeAs.kt b/compiler/testData/diagnostics/tests/smartCasts/safeAs.kt
new file mode 100644
index 00000000000..50250d74c35
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safeAs.kt
@@ -0,0 +1,17 @@
+// See also KT-10992: we should have no errors for all unsafe hashCode() calls
+
+fun foo(arg: Any?) {
+    val x = arg as? Any ?: return
+    <!DEBUG_INFO_SMARTCAST!>arg<!>.hashCode()
+    x.hashCode()
+}
+
+fun bar(arg: Any?) {
+    arg as? Any ?: return
+    <!DEBUG_INFO_SMARTCAST!>arg<!>.hashCode()
+}
+
+fun gav(arg: Any?) {
+    arg as? String ?: return
+    <!DEBUG_INFO_SMARTCAST!>arg<!>.length
+}
diff --git a/compiler/testData/diagnostics/tests/smartCasts/safeAs.txt b/compiler/testData/diagnostics/tests/smartCasts/safeAs.txt
new file mode 100644
index 00000000000..cc247d832be
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/smartCasts/safeAs.txt
@@ -0,0 +1,5 @@
+package
+
+public fun bar(/*0*/ arg: kotlin.Any?): kotlin.Unit
+public fun foo(/*0*/ arg: kotlin.Any?): kotlin.Unit
+public fun gav(/*0*/ arg: kotlin.Any?): kotlin.Unit
diff --git a/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java b/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java
index 7dd52e6d963..84912ad796d 100644
--- a/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java
+++ b/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java
@@ -16455,6 +16455,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("safeAs.kt")
+            public void testSafeAs() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/safeAs.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("shortIfExprNotNull.kt")
             public void testShortIfExprNotNull() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/shortIfExprNotNull.kt");