Captured value initialization is no more allowed #KT-10445 Fixed

compiler/frontend/src/org/jetbrains/kotlin/cfg/ControlFlowInformationProvider.java

@@ -391,6 +391,22 @@ public class ControlFlowInformationProvider {
         }
     }
 
+    private boolean isCapturedWrite(
+            @NotNull VariableDescriptor variableDescriptor,
+            @NotNull WriteValueInstruction writeValueInstruction
+    ) {
+        DeclarationDescriptor containingDeclarationDescriptor = variableDescriptor.getContainingDeclaration();
+        if (containingDeclarationDescriptor instanceof ClassDescriptor) return false;
+        KtElement ownerElement = writeValueInstruction.getOwner().getCorrespondingElement();
+        DeclarationDescriptor writeOwnerDescriptor = trace.get(BindingContext.DECLARATION_TO_DESCRIPTOR, ownerElement);
+        if (containingDeclarationDescriptor.equals(writeOwnerDescriptor)) return false;
+        if (writeOwnerDescriptor instanceof ClassDescriptor) {
+            ClassDescriptor writeOwnerClass = (ClassDescriptor) writeOwnerDescriptor;
+            if (containingDeclarationDescriptor.equals(writeOwnerClass.getUnsubstitutedPrimaryConstructor())) return false;
+        }
+        return true;
+    }
+
     private boolean checkValReassignment(
             @NotNull VariableInitContext ctxt,
             @NotNull KtExpression expression,
@@ -434,7 +450,8 @@ public class ControlFlowInformationProvider {
         }
         boolean isThisOrNoDispatchReceiver =
                 PseudocodeUtil.isThisOrNoDispatchReceiver(writeValueInstruction, trace.getBindingContext());
-        if ((mayBeInitializedNotHere || !hasBackingField || !isThisOrNoDispatchReceiver) && !variableDescriptor.isVar()) {
+        boolean captured = isCapturedWrite(variableDescriptor, writeValueInstruction);
+        if ((mayBeInitializedNotHere || !hasBackingField || !isThisOrNoDispatchReceiver || captured) && !variableDescriptor.isVar()) {
             boolean hasReassignMethodReturningUnit = false;
             KtSimpleNameExpression operationReference = null;
             PsiElement parent = expression.getParent();
@@ -465,7 +482,12 @@ public class ControlFlowInformationProvider {
             }
             if (!hasReassignMethodReturningUnit) {
                 if (!isThisOrNoDispatchReceiver || !varWithValReassignErrorGenerated.contains(variableDescriptor)) {
-                    report(Errors.VAL_REASSIGNMENT.on(expression, variableDescriptor), ctxt);
+                    if (captured && !mayBeInitializedNotHere && hasBackingField && isThisOrNoDispatchReceiver) {
+                        report(Errors.CAPTURED_VAL_INITIALIZATION.on(expression, variableDescriptor), ctxt);
+                    }
+                    else {
+                        report(Errors.VAL_REASSIGNMENT.on(expression, variableDescriptor), ctxt);
+                    }
                 }
                 if (isThisOrNoDispatchReceiver) {
                     // try to get rid of repeating VAL_REASSIGNMENT diagnostic only for vars with no receiver

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java

@@ -645,6 +645,7 @@ public interface Errors {
     DiagnosticFactory0<KtLambdaExpression> UNUSED_LAMBDA_EXPRESSION = DiagnosticFactory0.create(WARNING);
 
     DiagnosticFactory1<KtExpression, DeclarationDescriptor> VAL_REASSIGNMENT = DiagnosticFactory1.create(ERROR);
+    DiagnosticFactory1<KtExpression, DeclarationDescriptor> CAPTURED_VAL_INITIALIZATION = DiagnosticFactory1.create(ERROR);
     DiagnosticFactory1<KtExpression, DeclarationDescriptor> SETTER_PROJECTED_OUT = DiagnosticFactory1.create(ERROR);
 
     DiagnosticFactory1<KtExpression, DeclarationDescriptor> INITIALIZATION_BEFORE_DECLARATION = DiagnosticFactory1.create(ERROR);

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java

@@ -268,6 +268,7 @@ public class DefaultErrorMessages {
         MAP.put(UNUSED_LAMBDA_EXPRESSION, "The lambda expression is unused. If you mean a block, you can use 'run { ... }'");
 
         MAP.put(VAL_REASSIGNMENT, "Val cannot be reassigned", NAME);
+        MAP.put(CAPTURED_VAL_INITIALIZATION, "Captured values initialization is forbidden due to possible reassignment", NAME);
         MAP.put(SETTER_PROJECTED_OUT, "Setter for ''{0}'' is removed by type projection", NAME);
         MAP.put(INVISIBLE_SETTER, "Cannot assign to ''{0}'': the setter is ''{1}'' in {2}", NAME, TO_STRING, NAME_OF_PARENT_OR_FILE);
         MAP.put(INITIALIZATION_BEFORE_DECLARATION, "Variable cannot be initialized before declaration", NAME);

compiler/testData/diagnostics/tests/controlFlowAnalysis/initInLambda.kt

@@ -0,0 +1,77 @@
+// !DIAGNOSTICS: -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE
+
+fun ignoreIt(<!UNUSED_PARAMETER!>f<!>: () -> Unit) {}
+
+fun exec(f: () -> Unit) = f()
+
+fun foo() {
+    var x: Int
+    ignoreIt() {
+        // Ok
+        x = 42
+    }
+    // Error!
+    <!UNINITIALIZED_VARIABLE!>x<!>.hashCode()
+}
+
+fun bar() {
+    val x: Int
+    exec {
+        <!CAPTURED_VAL_INITIALIZATION!>x<!> = 13
+    }
+}
+
+fun bar2() {
+    val x: Int
+    fun foo() {
+        <!CAPTURED_VAL_INITIALIZATION!>x<!> = 3
+    }
+    foo()
+}
+
+class My(val cond: Boolean) {
+
+    val y: Int
+
+    init {
+        val x: Int
+        if (cond) {
+            exec {
+
+            }
+            x = 1
+        }
+        else {
+            x = 2
+        }
+        y = x
+    }
+
+    constructor(): this(false) {
+        val x: Int
+        x = 2
+        exec {
+            x.hashCode()
+        }
+    }
+}
+
+class Your {
+    val y = if (true) {
+        val xx: Int
+        exec {
+            <!CAPTURED_VAL_INITIALIZATION!>xx<!> = 42
+        }
+        24
+    }
+    else 0
+}
+
+val z = if (true) {
+    val xx: Int
+    exec {
+        <!CAPTURED_VAL_INITIALIZATION!>xx<!> = 24
+    }
+    42
+}
+else 0

compiler/testData/diagnostics/tests/controlFlowAnalysis/initInLambda.txt

@@ -0,0 +1,26 @@
+package
+
+public val z: kotlin.Int
+public fun bar(): kotlin.Unit
+public fun bar2(): kotlin.Unit
+public fun exec(/*0*/ f: () -> kotlin.Unit): kotlin.Unit
+public fun foo(): kotlin.Unit
+public fun ignoreIt(/*0*/ f: () -> kotlin.Unit): kotlin.Unit
+
+public final class My {
+    public constructor My()
+    public constructor My(/*0*/ cond: kotlin.Boolean)
+    public final val cond: kotlin.Boolean
+    public final val y: kotlin.Int
+    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 Your {
+    public constructor Your()
+    public final val y: kotlin.Int
+    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/DiagnosticsTestGenerated.java

@@ -2889,9 +2889,15 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 doTest(fileName);
             }
 
-            @TestMetadata("initializationInLambda.kt")
-            public void testInitializationInLambda() throws Exception {
-                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/controlFlowAnalysis/initializationInLambda.kt");
+            @TestMetadata("initInLambda.kt")
+            public void testInitInLambda() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/controlFlowAnalysis/initInLambda.kt");
+                doTest(fileName);
+            }
+
+            @TestMetadata("initializationInLocalFun.kt")
+            public void testInitializationInLocalFun() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/controlFlowAnalysis/initializationInLocalFun.kt");
                 doTest(fileName);
             }
 

idea/src/org/jetbrains/kotlin/idea/j2k/J2kPostProcessings.kt

@@ -93,16 +93,21 @@ object J2KPostProcessingRegistrar {
         }
 
         registerDiagnosticBasedProcessingFactory(
-                Errors.VAL_REASSIGNMENT,
-                fun (element: KtSimpleNameExpression, diagnostic: Diagnostic): (() -> Unit)? {
-                    val property = element.mainReference.resolve() as? KtProperty ?: return null
-                    return {
-                        if (!property.isVar) {
-                            property.valOrVarKeyword.replace(KtPsiFactory(element.project).createVarKeyword())
-                        }
+                Errors.VAL_REASSIGNMENT, Errors.CAPTURED_VAL_INITIALIZATION
+        ) {
+            element: KtSimpleNameExpression, diagnostic: Diagnostic ->
+            val property = element.mainReference.resolve() as? KtProperty
+            if (property == null) {
+                null
+            }
+            else {
+                {
+                    if (!property.isVar) {
+                        property.valOrVarKeyword.replace(KtPsiFactory(element.project).createVarKeyword())
                     }
                 }
-        )
+            }
+        }
     }
 
     private inline fun <reified TElement : KtElement, TIntention: SelfTargetingRangeIntention<TElement>> registerIntentionBasedProcessing(
@@ -132,20 +137,20 @@ object J2KPostProcessingRegistrar {
     }
 
     private inline fun <reified TElement : KtElement> registerDiagnosticBasedProcessing(
-            diagnosticFactory: DiagnosticFactory<*>,
+            vararg diagnosticFactory: DiagnosticFactory<*>,
             crossinline fix: (TElement, Diagnostic) -> Unit
     ) {
-        registerDiagnosticBasedProcessingFactory(diagnosticFactory) { element: TElement, diagnostic: Diagnostic -> { fix(element, diagnostic) } }
+        registerDiagnosticBasedProcessingFactory(*diagnosticFactory) { element: TElement, diagnostic: Diagnostic -> { fix(element, diagnostic) } }
     }
 
     private inline fun <reified TElement : KtElement> registerDiagnosticBasedProcessingFactory(
-            diagnosticFactory: DiagnosticFactory<*>,
+            vararg diagnosticFactory: DiagnosticFactory<*>,
             crossinline fixFactory: (TElement, Diagnostic) -> (() -> Unit)?
     ) {
         _processings.add(object : J2kPostProcessing {
             override fun createAction(element: KtElement, diagnostics: Diagnostics): (() -> Unit)? {
                 if (!TElement::class.java.isInstance(element)) return null
-                val diagnostic = diagnostics.forElement(element).firstOrNull { it.factory == diagnosticFactory } ?: return null
+                val diagnostic = diagnostics.forElement(element).firstOrNull { it.factory in diagnosticFactory } ?: return null
                 return fixFactory(element as TElement, diagnostic)
             }
         })

idea/src/org/jetbrains/kotlin/idea/quickfix/ChangeVariableMutabilityFix.kt

@@ -20,7 +20,9 @@ import com.intellij.codeInsight.intention.IntentionAction
 import com.intellij.openapi.editor.Editor
 import com.intellij.openapi.project.Project
 import com.intellij.psi.PsiFile
+import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
 import org.jetbrains.kotlin.diagnostics.Diagnostic
+import org.jetbrains.kotlin.diagnostics.DiagnosticFactory1
 import org.jetbrains.kotlin.diagnostics.Errors
 import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.psi.*
@@ -51,14 +53,18 @@ class ChangeVariableMutabilityFix(element: KtValVarKeywordOwner, private val mak
             }
         }
 
-        val VAL_REASSIGNMENT_FACTORY: KotlinSingleIntentionActionFactory = object: KotlinSingleIntentionActionFactory() {
+        class ReassignmentActionFactory(val factory: DiagnosticFactory1<*, DeclarationDescriptor>) : KotlinSingleIntentionActionFactory() {
             override fun createAction(diagnostic: Diagnostic): IntentionAction? {
-                val propertyDescriptor = Errors.VAL_REASSIGNMENT.cast(diagnostic).a
+                val propertyDescriptor = factory.cast(diagnostic).a
                 val declaration = DescriptorToSourceUtils.descriptorToDeclaration(propertyDescriptor) as? KtValVarKeywordOwner ?: return null
                 return ChangeVariableMutabilityFix(declaration, true)
             }
         }
 
+        val VAL_REASSIGNMENT_FACTORY = ReassignmentActionFactory(Errors.VAL_REASSIGNMENT)
+
+        val CAPTURED_VAL_INITIALIZATION_FACTORY = ReassignmentActionFactory(Errors.CAPTURED_VAL_INITIALIZATION)
+
         val VAR_OVERRIDDEN_BY_VAL_FACTORY: KotlinSingleIntentionActionFactory = object: KotlinSingleIntentionActionFactory() {
             override fun createAction(diagnostic: Diagnostic): IntentionAction? {
                 val element = diagnostic.psiElement

idea/src/org/jetbrains/kotlin/idea/quickfix/QuickFixRegistrar.kt

@@ -166,6 +166,7 @@ class QuickFixRegistrar : QuickFixContributor {
 
         VAL_WITH_SETTER.registerFactory(ChangeVariableMutabilityFix.VAL_WITH_SETTER_FACTORY)
         VAL_REASSIGNMENT.registerFactory(ChangeVariableMutabilityFix.VAL_REASSIGNMENT_FACTORY)
+        CAPTURED_VAL_INITIALIZATION.registerFactory(ChangeVariableMutabilityFix.CAPTURED_VAL_INITIALIZATION_FACTORY)
         VAR_OVERRIDDEN_BY_VAL.registerFactory(ChangeVariableMutabilityFix.VAR_OVERRIDDEN_BY_VAL_FACTORY)
 
         VAL_OR_VAR_ON_FUN_PARAMETER.registerFactory(RemoveValVarFromParameterFix)

idea/testData/quickfix/variables/changeMutability/capturedValInitialization.kt

@@ -0,0 +1,9 @@
+// "Make variable mutable" "true"
+fun exec(f: () -> Unit) = f()
+
+fun foo() {
+    val x: Int
+    exec {
+        <caret>x = 42
+    }
+}

idea/testData/quickfix/variables/changeMutability/capturedValInitialization.kt.after

@@ -0,0 +1,9 @@
+// "Make variable mutable" "true"
+fun exec(f: () -> Unit) = f()
+
+fun foo() {
+    var x: Int
+    exec {
+        x = 42
+    }
+}

idea/tests/org/jetbrains/kotlin/idea/quickfix/QuickFixTestGenerated.java

@@ -7728,6 +7728,12 @@ public class QuickFixTestGenerated extends AbstractQuickFixTest {
                 KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("idea/testData/quickfix/variables/changeMutability"), Pattern.compile("^([\\w\\-_]+)\\.kt$"), true);
             }
 
+            @TestMetadata("capturedValInitialization.kt")
+            public void testCapturedValInitialization() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("idea/testData/quickfix/variables/changeMutability/capturedValInitialization.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("funParameter.kt")
             public void testFunParameter() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("idea/testData/quickfix/variables/changeMutability/funParameter.kt");