Call chains: receiver data flow info is dropped for extensions with nullable receiver #KT-10056 Fixed

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/CallExpressionResolver.java

@@ -413,9 +413,15 @@ public class CallExpressionResolver {
 
             boolean lastStage = element.getQualified() == expression;
             // Drop NO_EXPECTED_TYPE / INDEPENDENT at last stage
-            // But receiver data flow info changes should be always applied, while we are inside call chain
             ExpressionTypingContext baseContext = lastStage ? context : currentContext;
-            contextForSelector = baseContext.replaceDataFlowInfo(receiverDataFlowInfo);
+            if (TypeUtils.isNullableType(receiverType) && !element.getSafe()) {
+                // Call with nullable receiver: take unconditional data flow info
+                contextForSelector = baseContext.replaceDataFlowInfo(unconditionalDataFlowInfo);
+            }
+            else {
+                // Take data flow info from the current receiver
+                contextForSelector = baseContext.replaceDataFlowInfo(receiverDataFlowInfo);
+            }
 
             if (receiver.exists() && receiver instanceof ReceiverValue) {
                 DataFlowValue receiverDataFlowValue = DataFlowValueFactory.createDataFlowValue((ReceiverValue) receiver, context);

compiler/testData/diagnostics/tests/smartCasts/safecalls/chainMixedUnsafe.kt

@@ -1,6 +1,5 @@
 fun calc(x: List<String>?): Int {
-    // x should be non-null in arguments list, despite of a chain
-    x?.subList(0, 1)<!UNSAFE_CALL!>.<!>get(<!DEBUG_INFO_SMARTCAST!>x<!>.size)
-    // But not here!
+    // x is not-null only inside subList
+    x?.subList(0, <!DEBUG_INFO_SMARTCAST!>x<!>.size - 1)<!UNSAFE_CALL!>.<!>get(x<!UNSAFE_CALL!>.<!>size)
     return x!!.size
 }

compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiver.kt

@@ -0,0 +1,15 @@
+// See KT-10056
+class Foo(val bar: String)
+
+public inline fun <T, R> T.let(f: (T) -> R): R = f(this)
+
+fun test(foo: Foo?) {
+    foo?.bar.let {
+        // Error, foo?.bar is nullable
+        it<!UNSAFE_CALL!>.<!>length
+        // Error, foo is nullable
+        foo<!UNSAFE_CALL!>.<!>bar.length
+        // Correct
+        foo?.bar?.length
+    }
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiver.txt

@@ -0,0 +1,12 @@
+package
+
+public fun test(/*0*/ foo: Foo?): kotlin.Unit
+public inline fun </*0*/ T, /*1*/ R> T.let(/*0*/ f: (T) -> R): R
+
+public final class Foo {
+    public constructor Foo(/*0*/ bar: kotlin.String)
+    public final val bar: kotlin.String
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiverInLongChain.kt

@@ -0,0 +1,44 @@
+class Bar(val gav: String)
+
+class Foo(val bar: Bar, val nbar: Bar?) {
+    fun baz(s: String) = if (s != "") Bar(s) else null
+}
+
+public inline fun <T, R> T.let(f: (T) -> R): R = f(this)
+
+fun String?.call(f: (String?) -> String?) = f(this)
+
+fun String.notNullLet(f: (String) -> Unit) = f(this)
+
+fun test(foo: Foo?) {
+    foo?.bar?.gav.let {
+        // Error, foo?.bar?.gav is nullable
+        it<!UNSAFE_CALL!>.<!>length
+        // Error, foo is nullable
+        foo<!UNSAFE_CALL!>.<!>bar.gav.length
+        // Correct
+        foo?.bar?.gav?.length
+    }
+    foo?.bar?.gav.call { it }?.notNullLet {
+        foo<!UNSAFE_CALL!>.<!>hashCode()
+        foo<!UNSAFE_CALL!>.<!>bar.hashCode()
+    }
+}
+
+fun testNotNull(foo: Foo) {
+    val s: String? = ""
+    foo.baz(s!!)?.gav.let {
+        it<!UNSAFE_CALL!>.<!>length
+        // Ok because of foo.
+        <!DEBUG_INFO_SMARTCAST!>s<!>.length.hashCode()
+    }
+}
+
+fun testNullable(foo: Foo?) {
+    val s: String? = ""
+    foo?.baz(s!!)?.gav.let {
+        it<!UNSAFE_CALL!>.<!>length
+        // Ok because of foo?.
+        s?.length?.hashCode()
+    }
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiverInLongChain.txt

@@ -0,0 +1,26 @@
+package
+
+public fun test(/*0*/ foo: Foo?): kotlin.Unit
+public fun testNotNull(/*0*/ foo: Foo): kotlin.Unit
+public fun testNullable(/*0*/ foo: Foo?): kotlin.Unit
+public fun kotlin.String?.call(/*0*/ f: (kotlin.String?) -> kotlin.String?): kotlin.String?
+public inline fun </*0*/ T, /*1*/ R> T.let(/*0*/ f: (T) -> R): R
+public fun kotlin.String.notNullLet(/*0*/ f: (kotlin.String) -> kotlin.Unit): kotlin.Unit
+
+public final class Bar {
+    public constructor Bar(/*0*/ gav: kotlin.String)
+    public final val gav: kotlin.String
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public final class Foo {
+    public constructor Foo(/*0*/ bar: Bar, /*1*/ nbar: Bar?)
+    public final val bar: Bar
+    public final val nbar: Bar?
+    public final fun baz(/*0*/ s: kotlin.String): Bar?
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiverWithExclExcl.kt

@@ -0,0 +1,13 @@
+class Foo(val bar: String?)
+
+public inline fun <T, R> T.let(f: (T) -> R): R = f(this)
+
+fun test(foo: Foo?) {
+    foo!!.bar.let {
+        // Correct
+        <!DEBUG_INFO_SMARTCAST!>foo<!>.bar?.length
+        // Unnecessary
+        foo<!UNNECESSARY_SAFE_CALL!>?.<!>bar?.length
+    }
+    <!DEBUG_INFO_SMARTCAST!>foo<!>.bar?.length
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiverWithExclExcl.txt

@@ -0,0 +1,12 @@
+package
+
+public fun test(/*0*/ foo: Foo?): kotlin.Unit
+public inline fun </*0*/ T, /*1*/ R> T.let(/*0*/ f: (T) -> R): R
+
+public final class Foo {
+    public constructor Foo(/*0*/ bar: kotlin.String?)
+    public final val bar: kotlin.String?
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiverWithFlexible.kt

@@ -0,0 +1,27 @@
+// FILE: Foo.java
+public class Foo {
+    public String bar;
+
+    private Foo(String bar) {
+        this.bar = bar;
+    }
+
+    public static Foo create(String bar) {
+        return new Foo(bar);
+    }
+}
+
+// FILE: Test.kt
+public inline fun <T, R> T.let(f: (T) -> R): R = f(this)
+
+fun test() {
+    val foo = Foo.create(null)
+    foo?.bar.let {
+        // Error, foo?.bar is nullable
+        it<!UNSAFE_CALL!>.<!>length
+        // Foo is nullable but flexible, so call is considered safe here
+        foo.bar.length
+        // Correct
+        foo?.bar?.length
+    }
+}

compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiverWithFlexible.txt

@@ -0,0 +1,15 @@
+package
+
+public fun test(): kotlin.Unit
+public inline fun </*0*/ T, /*1*/ R> T.let(/*0*/ f: (T) -> R): R
+
+public open class Foo {
+    private constructor Foo(/*0*/ bar: kotlin.String!)
+    public final var bar: kotlin.String!
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+
+    // Static members
+    public open fun create(/*0*/ bar: kotlin.String!): Foo!
+}

compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -15608,6 +15608,30 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                     doTest(fileName);
                 }
 
+                @TestMetadata("nullableReceiver.kt")
+                public void testNullableReceiver() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiver.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("nullableReceiverInLongChain.kt")
+                public void testNullableReceiverInLongChain() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiverInLongChain.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("nullableReceiverWithExclExcl.kt")
+                public void testNullableReceiverWithExclExcl() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiverWithExclExcl.kt");
+                    doTest(fileName);
+                }
+
+                @TestMetadata("nullableReceiverWithFlexible.kt")
+                public void testNullableReceiverWithFlexible() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/safecalls/nullableReceiverWithFlexible.kt");
+                    doTest(fileName);
+                }
+
                 @TestMetadata("property.kt")
                 public void testProperty() throws Exception {
                     String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/safecalls/property.kt");