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KT-7715 Highlight var's that can be replaced by val's
 #KT-7715 Fixed
1 parent e5b5a8d commit 28c5dde

28 files changed

+350
-15
lines changed

‎compiler/frontend/src/org/jetbrains/kotlin/psi/KtDestructuringDeclaration.java

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@@ -53,6 +53,11 @@ public KtExpression getInitializer() {
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return PsiTreeUtil.getNextSiblingOfType(eqNode.getPsi(), KtExpression.class);
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}
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public boolean isVar() {
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return getNode().findChildByType(KtTokens.VAR_KEYWORD) != null;
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}
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@Override
5661
@Nullable
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public PsiElement getValOrVarKeyword() {
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return findChildByType(TokenSet.create(VAL_KEYWORD, VAR_KEYWORD));

‎idea/resources/inspectionDescriptions/CanBeVal.html

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<html>
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<body>
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This inspection reports mutable local variables (declared with 'var' keyword) that can be made immutable.
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</body>
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</html>

‎idea/src/META-INF/plugin.xml

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@@ -1391,6 +1391,13 @@
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cleanupTool="false"
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level="WEAK WARNING"/>
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<localInspection implementationClass="org.jetbrains.kotlin.idea.inspections.CanBeValInspection"
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displayName="Local 'var' can be declared as 'val'"
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groupName="Kotlin"
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enabledByDefault="true"
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level="WARNING"
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/>
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<referenceImporter implementation="org.jetbrains.kotlin.idea.quickfix.KotlinReferenceImporter"/>
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<fileType.fileViewProviderFactory filetype="KJSM" implementationClass="com.intellij.psi.ClassFileViewProviderFactory"/>

‎idea/src/org/jetbrains/kotlin/idea/inspections/CanBeValInspection.kt

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/*
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* Copyright 2010-2016 JetBrains s.r.o.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.jetbrains.kotlin.idea.inspections
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import com.intellij.codeInspection.IntentionWrapper
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import com.intellij.codeInspection.ProblemHighlightType
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import com.intellij.codeInspection.ProblemsHolder
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import com.intellij.psi.PsiElementVisitor
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import com.intellij.psi.search.searches.ReferencesSearch
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import org.jetbrains.kotlin.cfg.pseudocode.Pseudocode
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import org.jetbrains.kotlin.cfg.pseudocode.PseudocodeUtil
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import org.jetbrains.kotlin.cfg.pseudocode.containingDeclarationForPseudocode
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import org.jetbrains.kotlin.cfg.pseudocode.instructions.Instruction
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import org.jetbrains.kotlin.cfg.pseudocode.instructions.InstructionWithNext
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import org.jetbrains.kotlin.cfg.pseudocode.instructions.eval.AccessTarget
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import org.jetbrains.kotlin.cfg.pseudocode.instructions.eval.WriteValueInstruction
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import org.jetbrains.kotlin.idea.caches.resolve.analyze
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import org.jetbrains.kotlin.idea.quickfix.ChangeVariableMutabilityFix
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import org.jetbrains.kotlin.idea.references.KtSimpleNameReference
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import org.jetbrains.kotlin.idea.references.readWriteAccess
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import org.jetbrains.kotlin.psi.*
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import org.jetbrains.kotlin.resolve.BindingContext
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import org.jetbrains.kotlin.resolve.lazy.BodyResolveMode
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import java.util.*
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class CanBeValInspection : AbstractKotlinInspection() {
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override fun buildVisitor(holder: ProblemsHolder, isOnTheFly: Boolean): PsiElementVisitor {
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return object: KtVisitorVoid() {
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private val pseudocodeCache = HashMap<KtDeclaration, Pseudocode>()
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override fun visitDeclaration(declaration: KtDeclaration) {
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super.visitDeclaration(declaration)
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when (declaration) {
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is KtProperty -> {
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if (declaration.isVar && declaration.isLocal && canBeVal(declaration, declaration.hasInitializer(), listOf(declaration))) {
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reportCanBeVal(declaration)
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}
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}
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is KtDestructuringDeclaration -> {
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val entries = declaration.entries
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if (declaration.isVar && entries.all { canBeVal(it, true, entries) }) {
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reportCanBeVal(declaration)
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}
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}
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}
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}
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private fun canBeVal(declaration: KtVariableDeclaration, hasInitializer: Boolean, allDeclarations: Collection<KtVariableDeclaration>): Boolean {
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if (allDeclarations.all { ReferencesSearch.search(it, it.useScope).none() }) {
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// do not report for unused var's (otherwise we'll get it highlighted immediately after typing the declaration
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return false
68+
}
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if (hasInitializer) {
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val hasWriteUsages = ReferencesSearch.search(declaration, declaration.useScope).any {
72+
(it as? KtSimpleNameReference)?.element?.readWriteAccess(useResolveForReadWrite = true)?.isWrite == true
73+
}
74+
return !hasWriteUsages
75+
}
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else {
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val bindingContext = declaration.analyze(BodyResolveMode.FULL)
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val pseudocode = pseudocode(declaration, bindingContext) ?: return false
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val descriptor = bindingContext[BindingContext.DECLARATION_TO_DESCRIPTOR, declaration] ?: return false
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val writeInstructions = pseudocode.instructionsIncludingDeadCode
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.filterIsInstance<WriteValueInstruction>()
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.filter { (it.target as? AccessTarget.Call)?.resolvedCall?.resultingDescriptor == descriptor }
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.toSet()
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if (writeInstructions.isEmpty()) return false // incorrect code - do not report
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return writeInstructions.none { canReach(it, writeInstructions) }
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}
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}
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private fun pseudocode(element: KtElement, bindingContext: BindingContext): Pseudocode? {
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val declaration = element.containingDeclarationForPseudocode ?: return null
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return pseudocodeCache.getOrPut(declaration) { PseudocodeUtil.generatePseudocode(declaration, bindingContext) }
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}
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private fun canReach(from: Instruction, targets: Set<Instruction>, visited: HashSet<Instruction> = HashSet<Instruction>()): Boolean {
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// special algorithm for linear code to avoid too deep recursion
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var instruction = from
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while (instruction is InstructionWithNext) {
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val next = instruction.next ?: return false
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if (next in visited) continue
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if (next in targets) return true
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visited.add(next)
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instruction = next
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}
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for (next in instruction.nextInstructions) {
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if (next in visited) continue
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if (next in targets) return true
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visited.add(next)
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if (canReach(next, targets)) return true
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}
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return false
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}
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private fun reportCanBeVal(declaration: KtValVarKeywordOwner) {
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val problemDescriptor = holder.manager.createProblemDescriptor(
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declaration,
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declaration.valOrVarKeyword!!,
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"Can be declared as 'val'",
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ProblemHighlightType.GENERIC_ERROR_OR_WARNING,
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isOnTheFly,
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IntentionWrapper(ChangeVariableMutabilityFix(declaration, false), declaration.containingFile)
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)
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holder.registerProblem(problemDescriptor)
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}
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}
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}
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}

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

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@@ -24,32 +24,23 @@ import org.jetbrains.kotlin.diagnostics.Diagnostic
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import org.jetbrains.kotlin.diagnostics.Errors
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import org.jetbrains.kotlin.lexer.KtTokens
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import org.jetbrains.kotlin.psi.*
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import org.jetbrains.kotlin.psi.psiUtil.getStrictParentOfType
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import org.jetbrains.kotlin.resolve.DescriptorToSourceUtils
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30-
class ChangeVariableMutabilityFix(element: KtNamedDeclaration, private val makeVar: Boolean) : KotlinQuickFixAction<KtNamedDeclaration>(element) {
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class ChangeVariableMutabilityFix(element: KtValVarKeywordOwner, private val makeVar: Boolean) : KotlinQuickFixAction<KtValVarKeywordOwner>(element) {
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override fun getText() = if (makeVar) "Make variable mutable" else "Make variable immutable"
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override fun getFamilyName(): String = text
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override fun isAvailable(project: Project, editor: Editor?, file: PsiFile): Boolean {
37-
return when (element) {
38-
is KtProperty -> element.isVar != makeVar
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is KtParameter ->
40-
element.getStrictParentOfType<KtPrimaryConstructor>()?.valueParameterList == element.parent
41-
&& (element.valOrVarKeyword == KtTokens.VAR_KEYWORD) != makeVar
42-
else -> false
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}
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val valOrVar = element.valOrVarKeyword?.node?.elementType ?: return false
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return (valOrVar == KtTokens.VAR_KEYWORD) != makeVar
4438
}
4539

4640
override fun invoke(project: Project, editor: Editor?, file: KtFile) {
4741
val factory = KtPsiFactory(project)
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val newKeyword = if (makeVar) factory.createVarKeyword() else factory.createValKeyword()
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when (element) {
50-
is KtProperty -> element.valOrVarKeyword.replace(newKeyword)
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is KtParameter -> element.valOrVarKeyword!!.replace(newKeyword)
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}
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element.valOrVarKeyword!!.replace(newKeyword)
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}
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5546
companion object {
@@ -63,7 +54,7 @@ class ChangeVariableMutabilityFix(element: KtNamedDeclaration, private val makeV
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val VAL_REASSIGNMENT_FACTORY: KotlinSingleIntentionActionFactory = object: KotlinSingleIntentionActionFactory() {
6455
override fun createAction(diagnostic: Diagnostic): IntentionAction? {
6556
val propertyDescriptor = Errors.VAL_REASSIGNMENT.cast(diagnostic).a
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val declaration = DescriptorToSourceUtils.descriptorToDeclaration(propertyDescriptor) as? KtNamedDeclaration ?: return null
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val declaration = DescriptorToSourceUtils.descriptorToDeclaration(propertyDescriptor) as? KtValVarKeywordOwner ?: return null
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return ChangeVariableMutabilityFix(declaration, true)
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}
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}
@@ -72,7 +63,7 @@ class ChangeVariableMutabilityFix(element: KtNamedDeclaration, private val makeV
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override fun createAction(diagnostic: Diagnostic): IntentionAction? {
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val element = diagnostic.psiElement
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return when (element) {
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is KtProperty, is KtParameter -> ChangeVariableMutabilityFix(element as KtNamedDeclaration, true)
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is KtProperty, is KtParameter -> ChangeVariableMutabilityFix(element as KtValVarKeywordOwner, true)
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else -> null
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}
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}

‎idea/testData/inspections/canBeVal/alwaysAssigned.kt

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fun foo(p: Int) {
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var v1: Int
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var v2: Int = 0
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if (p > 0) v1 = 1 else v1 = 2
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v2 = 1
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}

‎idea/testData/inspections/canBeVal/assignedInLoop.kt

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fun foo(p: Int) {
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var v: Int
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for (i in 1..10) {
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v = i
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}
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}

‎idea/testData/inspections/canBeVal/assignedTwice.kt

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fun foo(p: Int) {
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var v: Int
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v = 0
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if (p > 0) v = 1
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}

‎idea/testData/inspections/canBeVal/desctructuringDeclaration1.kt

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fun foo(p: Int) {
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var (v1, v2) = getPair()
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print(v1)
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}
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fun getPair(): Pair<Int, String> = 1 to ""

‎idea/testData/inspections/canBeVal/desctructuringDeclaration2.kt

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fun foo(p: Int) {
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var (v1, v2) = getPair()
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print(v1)
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v2 = ""
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}
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fun getPair(): Pair<Int, String> = 1 to ""

‎idea/testData/inspections/canBeVal/desctructuringDeclarationUnused.kt

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fun foo(p: Int) {
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var (v1, v2) = getPair()
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}
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fun getPair(): Pair<Int, String> = 1 to ""

‎idea/testData/inspections/canBeVal/inspectionData/expected.xml

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<problems>
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<problem>
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<file>withInitializer.kt</file>
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<line>4</line>
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<module>light_idea_test_case</module>
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<entry_point TYPE="file" FQNAME="withInitializer.kt" />
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<problem_class severity="WARNING" attribute_key="WARNING_ATTRIBUTES">Local 'var' can be declared as 'val'</problem_class>
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<description>Can be declared as 'val'</description>
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</problem>
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<problem>
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<file>alwaysAssigned.kt</file>
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<line>2</line>
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<module>light_idea_test_case</module>
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<entry_point TYPE="file" FQNAME="alwaysAssigned.kt" />
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<problem_class severity="WARNING" attribute_key="WARNING_ATTRIBUTES">Local 'var' can be declared as 'val'</problem_class>
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<description>Can be declared as 'val'</description>
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</problem>
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<problem>
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<file>notAssignedWhenNotUsed.kt</file>
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<line>2</line>
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<module>light_idea_test_case</module>
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<entry_point TYPE="file" FQNAME="notAssignedWhenNotUsed.kt" />
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<problem_class severity="WARNING" attribute_key="WARNING_ATTRIBUTES">Local 'var' can be declared as 'val'</problem_class>
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<description>Can be declared as 'val'</description>
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</problem>
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<problem>
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<file>twoVariables.kt</file>
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<line>2</line>
32+
<module>light_idea_test_case</module>
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<entry_point TYPE="file" FQNAME="twoVariables.kt" />
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<problem_class severity="WARNING" attribute_key="WARNING_ATTRIBUTES">Local 'var' can be declared as 'val'</problem_class>
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<description>Can be declared as 'val'</description>
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</problem>
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<problem>
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<file>twoVariables.kt</file>
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<line>3</line>
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<module>light_idea_test_case</module>
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<entry_point TYPE="file" FQNAME="twoVariables.kt" />
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<problem_class severity="WARNING" attribute_key="WARNING_ATTRIBUTES">Local 'var' can be declared as 'val'</problem_class>
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<description>Can be declared as 'val'</description>
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</problem>
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<problem>
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<file>desctructuringDeclaration1.kt</file>
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<line>2</line>
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<module>light_idea_test_case</module>
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<entry_point TYPE="file" FQNAME="desctructuringDeclaration1.kt" />
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<problem_class severity="WARNING" attribute_key="WARNING_ATTRIBUTES">Local 'var' can be declared as 'val'</problem_class>
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<description>Can be declared as 'val'</description>
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</problem>
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</problems>

‎idea/testData/inspections/canBeVal/inspectionData/inspections.test

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// INSPECTION_CLASS: org.jetbrains.kotlin.idea.inspections.CanBeValInspection

‎idea/testData/inspections/canBeVal/notAssignedWhenNotUsed.kt

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fun foo(p: Int) {
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var v: Int
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if (p > 0) {
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v = 1
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print(v)
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}
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}

‎idea/testData/inspections/canBeVal/onlyLocal.kt

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var global = 1
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class C {
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var field = 2
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fun foo() {
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print(field)
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print(global)
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}
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}

‎idea/testData/inspections/canBeVal/onlyVar.kt

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fun foo() {
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val v = 1
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print(v)
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}

‎idea/testData/inspections/canBeVal/twoVariables.kt

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fun foo(p: Int) {
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var v1: Int
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var v2: Int
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if (p > 0) v1 = 1 else v1 = 2
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v2 = 1
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}

‎idea/testData/inspections/canBeVal/unused.kt

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fun foo() {
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var v: Int
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}

‎idea/testData/inspections/canBeVal/unusedWithInitializer.kt

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fun foo() {
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var v = 1
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}

‎idea/testData/inspections/canBeVal/withInitializer.kt

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fun foo() {
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var v1 = 1
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var v2 = 2
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var v3 = 3
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v1 = 1
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v2++
7+
print(v3)
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}

‎idea/testData/quickfix/variables/changeMutability/canBeVal/.inspection

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org.jetbrains.kotlin.idea.inspections.CanBeValInspection

‎idea/testData/quickfix/variables/changeMutability/canBeVal/multiVariable.kt

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// "Make variable immutable" "true"
2+
fun foo(p: Int) {
3+
<caret>var (v1, v2) = getPair()!!
4+
v1
5+
}
6+
7+
fun getPair(): Pair<Int, String>? = null
8+
9+
data class Pair<T1, T2>(val a: T1, val b: T2)

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