Iterative call chain handling to get rid of JetTypeInfoInsideCallChain and other nasty things #KT-9754 Fixed

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

@@ -22,11 +22,11 @@ import com.intellij.psi.util.PsiTreeUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.kotlin.descriptors.*;
-import org.jetbrains.kotlin.lexer.KtTokens;
 import org.jetbrains.kotlin.psi.*;
 import org.jetbrains.kotlin.resolve.BindingContext;
 import org.jetbrains.kotlin.resolve.BindingTrace;
 import org.jetbrains.kotlin.resolve.DescriptorUtils;
+import org.jetbrains.kotlin.resolve.bindingContextUtil.BindingContextUtilsKt;
 import org.jetbrains.kotlin.resolve.calls.callUtil.CallUtilKt;
 import org.jetbrains.kotlin.resolve.calls.context.BasicCallResolutionContext;
 import org.jetbrains.kotlin.resolve.calls.context.CheckArgumentTypesMode;
@@ -53,6 +53,7 @@ import org.jetbrains.kotlin.types.expressions.typeInfoFactory.TypeInfoFactoryKt;
 
 import javax.inject.Inject;
 import java.util.Collections;
+import java.util.Deque;
 import java.util.List;
 
 import static org.jetbrains.kotlin.diagnostics.Errors.*;
@@ -307,31 +308,6 @@ public class CallExpressionResolver {
         return TypeInfoFactoryKt.noTypeInfo(context);
     }
 
-    /**
-     * Extended variant of JetTypeInfo stores additional information
-     * about data flow info from the left-more receiver, e.g. x != null for
-     * foo(x!!)?.bar(y!!)?.baz()
-     */
-    private static class JetTypeInfoInsideSafeCall extends JetTypeInfo {
-
-        private final DataFlowInfo safeCallChainInfo;
-
-        private JetTypeInfoInsideSafeCall(@NotNull JetTypeInfo typeInfo, @Nullable DataFlowInfo safeCallChainInfo) {
-            super(typeInfo.getType(), typeInfo.getDataFlowInfo(), typeInfo.getJumpOutPossible(), typeInfo.getJumpFlowInfo());
-            this.safeCallChainInfo = safeCallChainInfo;
-        }
-
-        /**
-         * Returns safe call chain information which is taken from the left-most receiver of a chain
-         * foo(x!!)?.bar(y!!)?.gav() ==> x != null is safe call chain information
-         */
-        @Nullable
-        public DataFlowInfo getSafeCallChainInfo() {
-            return safeCallChainInfo;
-        }
-    }
-
-
     /**
      * Visits a qualified expression like x.y or x?.z controlling data flow information changes.
      *
@@ -341,97 +317,82 @@ public class CallExpressionResolver {
     public JetTypeInfo getQualifiedExpressionTypeInfo(
             @NotNull KtQualifiedExpression expression, @NotNull ExpressionTypingContext context
     ) {
-        // TODO : functions as values
-        KtExpression selectorExpression = expression.getSelectorExpression();
-        KtExpression receiverExpression = expression.getReceiverExpression();
-        boolean safeCall = (expression.getOperationSign() == KtTokens.SAFE_ACCESS);
-        ResolutionContext contextForReceiver = context.replaceExpectedType(NO_EXPECTED_TYPE).
-                replaceContextDependency(INDEPENDENT).
-                replaceInsideCallChain(true); // Enter call chain
-        // Visit receiver (x in x.y or x?.z) here. Recursion is possible.
-        JetTypeInfo receiverTypeInfo = expressionTypingServices.getTypeInfo(receiverExpression, contextForReceiver);
+        ExpressionTypingContext currentContext = context.replaceExpectedType(NO_EXPECTED_TYPE).replaceContextDependency(INDEPENDENT);
+        Deque<CallExpressionElement> elementChain = CallExpressionUnrollerKt.unroll(expression);
+
+        JetTypeInfo receiverTypeInfo = expressionTypingServices.getTypeInfo(elementChain.getFirst().getReceiver(), currentContext);
         KotlinType receiverType = receiverTypeInfo.getType();
-        QualifierReceiver qualifierReceiver = (QualifierReceiver) context.trace.get(BindingContext.QUALIFIER, receiverExpression);
-
-        if (receiverType == null) receiverType = ErrorUtils.createErrorType("Type for " + expression.getText());
-
-        ReceiverValue receiver = qualifierReceiver == null ? new ExpressionReceiver(receiverExpression, receiverType) : qualifierReceiver;
         DataFlowInfo receiverDataFlowInfo = receiverTypeInfo.getDataFlowInfo();
-        // Receiver changes should be always applied, at least for argument analysis
-        context = context.replaceDataFlowInfo(receiverDataFlowInfo);
+        JetTypeInfo resultTypeInfo = receiverTypeInfo;
 
-        // Visit selector (y in x.y) here. Recursion is also possible.
-        JetTypeInfo selectorReturnTypeInfo = getSelectorReturnTypeInfo(
-                receiver, expression.getOperationTokenNode(), selectorExpression, context);
-        KotlinType selectorReturnType = selectorReturnTypeInfo.getType();
+        boolean unconditional = true;
+        DataFlowInfo unconditionalDataFlowInfo = receiverDataFlowInfo;
 
-        resolveDeferredReceiverInQualifiedExpression(qualifierReceiver, expression, context);
-        checkNestedClassAccess(expression, context);
+        for (CallExpressionElement element : elementChain) {
+            if (receiverType == null) {
+                receiverType = ErrorUtils.createErrorType("Type for " + expression.getText());
+            }
+            QualifierReceiver qualifierReceiver = (QualifierReceiver) context.trace.get(BindingContext.QUALIFIER, element.getReceiver());
 
-        //TODO move further
-        if (safeCall) {
-            if (selectorReturnType != null) {
-                if (TypeUtils.isNullableType(receiverType)) {
-                    selectorReturnType = TypeUtils.makeNullable(selectorReturnType);
-                    selectorReturnTypeInfo = selectorReturnTypeInfo.replaceType(selectorReturnType);
-                }
+            ReceiverValue receiver = qualifierReceiver == null ? new ExpressionReceiver(element.getReceiver(), receiverType) : qualifierReceiver;
+
+            boolean lastStage = element.getQualified() == expression;
+            assert lastStage == (element == elementChain.getLast());
+            // 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;
+            currentContext = baseContext.replaceDataFlowInfo(receiverDataFlowInfo);
+
+            KtExpression selectorExpression = element.getSelector();
+            JetTypeInfo selectorReturnTypeInfo = getSelectorReturnTypeInfo(receiver, element.getNode(), selectorExpression, currentContext);
+            KotlinType selectorReturnType = selectorReturnTypeInfo.getType();
+
+            resolveDeferredReceiverInQualifiedExpression(qualifierReceiver, element.getQualified(), currentContext);
+            checkNestedClassAccess(element.getQualified(), currentContext);
+
+            boolean safeCall = element.getSafe();
+            if (safeCall && selectorReturnType != null && TypeUtils.isNullableType(receiverType)) {
+                selectorReturnType = TypeUtils.makeNullable(selectorReturnType);
+                selectorReturnTypeInfo = selectorReturnTypeInfo.replaceType(selectorReturnType);
+            }
+
+            // TODO : this is suspicious: remove this code?
+            if (selectorExpression != null && selectorReturnType != null) {
+                currentContext.trace.recordType(selectorExpression, selectorReturnType);
+            }
+            resultTypeInfo = selectorReturnTypeInfo;
+            CompileTimeConstant<?> value = constantExpressionEvaluator.evaluateExpression(element.getQualified(), currentContext.trace, currentContext.expectedType);
+            if (value != null && value.isPure()) {
+                resultTypeInfo =  dataFlowAnalyzer.createCompileTimeConstantTypeInfo(value, element.getQualified(), currentContext);
+                if (lastStage) return resultTypeInfo;
+            }
+            if (currentContext.contextDependency == INDEPENDENT) {
+                dataFlowAnalyzer.checkType(resultTypeInfo.getType(), element.getQualified(), currentContext);
+            }
+            // For the next stage, if any, current stage selector is the receiver!
+            receiverTypeInfo = selectorReturnTypeInfo;
+            receiverType = selectorReturnType;
+            receiverDataFlowInfo = receiverTypeInfo.getDataFlowInfo();
+            // if we have only dots and not ?. move unconditional data flow info further
+            if (safeCall) {
+                unconditional = false;
+            }
+            else if (unconditional) {
+                unconditionalDataFlowInfo = receiverDataFlowInfo;
+            }
+            //noinspection ConstantConditions
+            if (!lastStage && !currentContext.trace.get(BindingContext.PROCESSED, element.getQualified())) {
+                // Store type information (to prevent problems in call completer)
+                currentContext.trace.record(BindingContext.PROCESSED, element.getQualified());
+                currentContext.trace.record(BindingContext.EXPRESSION_TYPE_INFO, element.getQualified(),
+                                            resultTypeInfo.replaceDataFlowInfo(unconditionalDataFlowInfo));
+                // save scope before analyze and fix debugger: see CodeFragmentAnalyzer.correctContextForExpression
+                BindingContextUtilsKt.recordScope(currentContext.trace, currentContext.scope, element.getQualified());
+                BindingContextUtilsKt.recordDataFlowInfo(currentContext.replaceDataFlowInfo(unconditionalDataFlowInfo), element.getQualified());
             }
         }
-        // TODO : this is suspicious: remove this code?
-        if (selectorExpression != null && selectorReturnType != null) {
-            context.trace.recordType(selectorExpression, selectorReturnType);
-        }
-
-        CompileTimeConstant<?> value = constantExpressionEvaluator.evaluateExpression(expression, context.trace, context.expectedType);
-        if (value != null && value.isPure()) {
-            return dataFlowAnalyzer.createCompileTimeConstantTypeInfo(value, expression, context);
-        }
-
-        JetTypeInfo typeInfo;
-        DataFlowInfo safeCallChainInfo;
-        if (receiverTypeInfo instanceof JetTypeInfoInsideSafeCall) {
-            safeCallChainInfo = ((JetTypeInfoInsideSafeCall) receiverTypeInfo).getSafeCallChainInfo();
-        }
-        else {
-            safeCallChainInfo = null;
-        }
-        if (safeCall) {
-            if (safeCallChainInfo == null) safeCallChainInfo = receiverDataFlowInfo;
-            if (context.insideCallChain) {
-                // If we are inside safe call chain, we SHOULD take arguments into account, for example
-                // x?.foo(y!!)?.bar(x.field)?.gav(y.field) (like smartCasts\safecalls\longChain)
-                // Also, we should provide further safe call chain data flow information or
-                // if we are in the most left safe call then just take it from receiver
-                typeInfo = new JetTypeInfoInsideSafeCall(selectorReturnTypeInfo, safeCallChainInfo);
-            }
-            else {
-                // Here we should not take selector data flow info into account because it's only one branch, see KT-7204
-                // x?.foo(y!!) // y becomes not-nullable during argument analysis
-                // y.bar()     // ERROR: y is nullable at this point
-                // So we should just take safe call chain data flow information, e.g. foo(x!!)?.bar()?.gav()
-                // If it's null, we must take receiver normal info, it's a chain with length of one like foo(x!!)?.bar() and
-                // safe call chain information does not yet exist
-                typeInfo = selectorReturnTypeInfo.replaceDataFlowInfo(safeCallChainInfo);
-            }
-        }
-        else {
-            // It's not a safe call, so we can take selector data flow information
-            // Safe call chain information also should be provided because it's can be a part of safe call chain
-            if (context.insideCallChain || safeCallChainInfo == null) {
-                // Not a safe call inside call chain with safe calls OR
-                // call chain without safe calls at all
-                typeInfo = new JetTypeInfoInsideSafeCall(selectorReturnTypeInfo, selectorReturnTypeInfo.getDataFlowInfo());
-            }
-            else {
-                // Exiting call chain with safe calls -- take data flow info from the lest-most receiver
-                // foo(x!!)?.bar().gav()
-                typeInfo = selectorReturnTypeInfo.replaceDataFlowInfo(safeCallChainInfo);
-            }
-        }
-        if (context.contextDependency == INDEPENDENT) {
-            dataFlowAnalyzer.checkType(typeInfo.getType(), expression, context);
-        }
-        return typeInfo;
+        // if we are at last stage, we should just take result type info and set unconditional data flow info
+        return resultTypeInfo.replaceDataFlowInfo(unconditionalDataFlowInfo);
     }
 
     private void resolveDeferredReceiverInQualifiedExpression(

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/CallExpressionUnroller.kt

@@ -0,0 +1,48 @@
+/*
+ * Copyright 2010-2015 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.kotlin.resolve.calls
+
+import com.intellij.lang.ASTNode
+import org.jetbrains.kotlin.lexer.KtTokens
+import org.jetbrains.kotlin.psi.KtExpression
+import org.jetbrains.kotlin.psi.KtQualifiedExpression
+import java.util.*
+
+internal fun unroll(root: KtQualifiedExpression): Deque<CallExpressionElement> {
+    var current: KtExpression = root
+    val result = linkedListOf<CallExpressionElement>()
+    while (current is KtQualifiedExpression) {
+        result.addFirst(CallExpressionElement(current))
+        current = result.first.receiver
+    }
+    return result
+}
+
+internal data class CallExpressionElement(val qualified: KtQualifiedExpression) {
+
+    val receiver: KtExpression
+        get() = qualified.receiverExpression
+
+    val selector: KtExpression?
+        get() = qualified.selectorExpression
+
+    val safe: Boolean
+        get() = qualified.operationSign == KtTokens.SAFE_ACCESS
+
+    val node: ASTNode
+        get() = qualified.operationTokenNode
+}

compiler/frontend/src/org/jetbrains/kotlin/types/expressions/JetTypeInfo.kt

@@ -30,7 +30,7 @@ import org.jetbrains.kotlin.types.KotlinType
  * At the end current data flow info is x != null && y != null, but jump data flow info is x != null only.
  * Both break and continue are counted as possible jump outside of a loop, but return is not.
  */
-/*package*/ open class JetTypeInfo(
+class JetTypeInfo(
         val type: KotlinType?,
         val dataFlowInfo: DataFlowInfo,
         val jumpOutPossible: Boolean = false,
@@ -39,7 +39,7 @@ import org.jetbrains.kotlin.types.KotlinType
 
     fun clearType() = replaceType(null)
 
-    // NB: do not compare type with this.type because this comparison is complex and unstabld
+    // NB: do not compare type with this.type because this comparison is complex and unstable
     fun replaceType(type: KotlinType?) = JetTypeInfo(type, dataFlowInfo, jumpOutPossible, jumpFlowInfo)
 
     fun replaceJumpOutPossible(jumpOutPossible: Boolean) =

compiler/testData/diagnostics/tests/smartCasts/extensionSafeCall.kt

@@ -0,0 +1,13 @@
+class Your
+
+fun Your.foo() = Any()
+
+fun <T> T?.let(f: (T) -> Unit) {
+    if (this != null) f(<!DEBUG_INFO_SMARTCAST!>this<!>)
+}
+
+fun test(your: Your?) {
+    (your?.foo() as? Any)?.let {}
+    // strange smart cast to 'Your' at this point
+    your<!UNSAFE_CALL!>.<!>hashCode()
+}

compiler/testData/diagnostics/tests/smartCasts/extensionSafeCall.txt

@@ -0,0 +1,12 @@
+package
+
+public fun test(/*0*/ your: Your?): kotlin.Unit
+public fun Your.foo(): kotlin.Any
+public fun </*0*/ T> T?.let(/*0*/ f: (T) -> kotlin.Unit): kotlin.Unit
+
+public final class Your {
+    public constructor Your()
+    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/tests/org/jetbrains/kotlin/checkers/JetDiagnosticsTestGenerated.java

@@ -14265,6 +14265,12 @@ public class JetDiagnosticsTestGenerated extends AbstractJetDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("extensionSafeCall.kt")
+            public void testExtensionSafeCall() throws Exception {
+                String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/extensionSafeCall.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("fieldExclExcl.kt")
             public void testFieldExclExcl() throws Exception {
                 String fileName = JetTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/smartCasts/fieldExclExcl.kt");