Add "unnecessary local variable" inspection #KT-15958 Fixed

2017-07-12 11:26:51 +03:00
parent 9d06a80519
commit 987c7f5be8
16 changed files with 232 additions and 0 deletions
@@ -0,0 +1,6 @@
+<html>
+<body>
+This inspection reports local variables either used only in the very next return or exact copies of other variables.
+In both cases it's better to inline such a variable.
+</body>
+</html>
@@ -2400,6 +2400,15 @@
                     language="kotlin"
    />

+    <localInspection implementationClass="org.jetbrains.kotlin.idea.inspections.UnnecessaryVariableInspection"
+                     displayName="Unnecessary local variable"
+                     groupPath="Kotlin"
+                     groupName="Redundant constructs"
+                     enabledByDefault="true"
+                     level="WEAK WARNING"
+                     language="kotlin"
+    />
+
    <referenceImporter implementation="org.jetbrains.kotlin.idea.quickfix.KotlinReferenceImporter"/>

    <fileType.fileViewProviderFactory filetype="KJSM" implementationClass="com.intellij.psi.ClassFileViewProviderFactory"/>
@@ -0,0 +1,95 @@
+/*
+ * Copyright 2010-2017 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.idea.inspections
+
+import com.intellij.codeInspection.LocalQuickFix
+import com.intellij.codeInspection.ProblemDescriptor
+import com.intellij.codeInspection.ProblemHighlightType
+import com.intellij.codeInspection.ProblemsHolder
+import com.intellij.openapi.project.Project
+import com.intellij.psi.PsiElementVisitor
+import org.jetbrains.kotlin.descriptors.FunctionDescriptor
+import org.jetbrains.kotlin.descriptors.VariableDescriptor
+import org.jetbrains.kotlin.idea.caches.resolve.analyze
+import org.jetbrains.kotlin.idea.refactoring.inline.KotlinInlineValHandler
+import org.jetbrains.kotlin.psi.KtNameReferenceExpression
+import org.jetbrains.kotlin.psi.KtProperty
+import org.jetbrains.kotlin.psi.KtReturnExpression
+import org.jetbrains.kotlin.psi.KtVisitorVoid
+import org.jetbrains.kotlin.psi.psiUtil.getNextSiblingIgnoringWhitespaceAndComments
+import org.jetbrains.kotlin.psi.psiUtil.getParentOfType
+import org.jetbrains.kotlin.resolve.BindingContext.DECLARATION_TO_DESCRIPTOR
+import org.jetbrains.kotlin.resolve.BindingContext.REFERENCE_TARGET
+
+class UnnecessaryVariableInspection : AbstractKotlinInspection() {
+
+    override fun buildVisitor(holder: ProblemsHolder, isOnTheFly: Boolean): PsiElementVisitor =
+            object : KtVisitorVoid() {
+                override fun visitProperty(property: KtProperty) {
+                    super.visitProperty(property)
+
+                    if (!property.isLocal) return
+                    val initializer = property.initializer ?: return
+                    val nameIdentifier = property.nameIdentifier ?: return
+
+                    if (!property.isVar && initializer is KtNameReferenceExpression && property.typeReference == null) {
+                        val context = property.analyze()
+                        val initializerDescriptor = context[REFERENCE_TARGET, initializer]
+                        if (initializerDescriptor is VariableDescriptor) {
+                            if (!initializerDescriptor.isVar &&
+                                initializerDescriptor.containingDeclaration is FunctionDescriptor) {
+                                holder.registerProblem(
+                                        nameIdentifier,
+                                        "Variable is an exact copy of another variable and can be inlined",
+                                        ProblemHighlightType.GENERIC_ERROR_OR_WARNING,
+                                        InlineVariableFix()
+                                )
+                                return
+                            }
+                        }
+                    }
+
+                    val nextStatement = property.getNextSiblingIgnoringWhitespaceAndComments()
+                    if (nextStatement is KtReturnExpression) {
+                        val returned = nextStatement.returnedExpression
+                        if (returned is KtNameReferenceExpression) {
+                            val context = nextStatement.analyze()
+                            if (context[REFERENCE_TARGET, returned] == context[DECLARATION_TO_DESCRIPTOR, property]) {
+                                holder.registerProblem(
+                                        nameIdentifier,
+                                        "Variable used only in following return and can be inlined",
+                                        ProblemHighlightType.GENERIC_ERROR_OR_WARNING,
+                                        InlineVariableFix()
+                                )
+                            }
+                        }
+                    }
+                }
+            }
+
+    class InlineVariableFix : LocalQuickFix {
+
+        override fun getName() = "Inline variable"
+
+        override fun getFamilyName() = name
+
+        override fun applyFix(project: Project, descriptor: ProblemDescriptor) {
+            val property = descriptor.psiElement.getParentOfType<KtProperty>(strict = true) ?: return
+            KotlinInlineValHandler().inlineElement(project, property.findExistingEditor(), property)
+        }
+    }
+}
@@ -0,0 +1 @@
+org.jetbrains.kotlin.idea.inspections.UnnecessaryVariableInspection
@@ -0,0 +1,5 @@
+fun test(): Int {
+    val x = 1
+    val <caret>y = x
+    return x + y
+}
@@ -0,0 +1,4 @@
+fun test(): Int {
+    val x = 1
+    return x + x
+}
@@ -0,0 +1,8 @@
+// PROBLEM: none
+
+fun test(): Int {
+    val x = 1
+    // With explicitly given type looks dangerous
+    val <caret>y: Int = x
+    return x + y
+}
@@ -0,0 +1,8 @@
+// PROBLEM: none
+
+fun test(): Int {
+    var x = 1
+    val <caret>y = x
+    x++
+    return x + y
+}
@@ -0,0 +1,4 @@
+fun sqr(arg: Int): Int {
+    val <caret>other = arg
+    return other * other
+}
@@ -0,0 +1,3 @@
+fun sqr(arg: Int): Int {
+    return arg * arg
+}
@@ -0,0 +1,9 @@
+// PROBLEM: none
+
+class My(val x: Number)
+
+fun My.foo(): Int {
+    val <caret>y = x
+    if (y is Int) return y
+    return 0
+}
@@ -0,0 +1,4 @@
+fun sum(a: Int, b: Int): Int {
+    val <caret>c = a + b
+    return c
+}
@@ -0,0 +1,3 @@
+fun sum(a: Int, b: Int): Int {
+    return a + b
+}
@@ -0,0 +1,9 @@
+// PROBLEM: none
+
+val x: Number? = null
+
+fun foo(): Int {
+    val <caret>y = x
+    if (y is Int) return y
+    return 0
+}
@@ -0,0 +1,7 @@
+// PROBLEM: none
+
+fun sqrPlusOne(arg: Int): Int {
+    var <caret>other = arg
+    other++
+    return other * other
+}
@@ -1458,6 +1458,63 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
        }
    }

+    @TestMetadata("idea/testData/inspectionsLocal/unnecessaryVariable")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class UnnecessaryVariable extends AbstractLocalInspectionTest {
+        public void testAllFilesPresentInUnnecessaryVariable() throws Exception {
+            KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("idea/testData/inspectionsLocal/unnecessaryVariable"), Pattern.compile("^([\\w\\-_]+)\\.kt$"), TargetBackend.ANY, true);
+        }
+
+        @TestMetadata("copyOfVal.kt")
+        public void testCopyOfVal() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/unnecessaryVariable/copyOfVal.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("copyOfValWithExplicitType.kt")
+        public void testCopyOfValWithExplicitType() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/unnecessaryVariable/copyOfValWithExplicitType.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("copyOfVar.kt")
+        public void testCopyOfVar() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/unnecessaryVariable/copyOfVar.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("paramCopy.kt")
+        public void testParamCopy() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/unnecessaryVariable/paramCopy.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("propertyCopy.kt")
+        public void testPropertyCopy() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/unnecessaryVariable/propertyCopy.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("simpleReturn.kt")
+        public void testSimpleReturn() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/unnecessaryVariable/simpleReturn.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("topLevelCopy.kt")
+        public void testTopLevelCopy() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/unnecessaryVariable/topLevelCopy.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("varCopy.kt")
+        public void testVarCopy() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/unnecessaryVariable/varCopy.kt");
+            doTest(fileName);
+        }
+    }
+
    @TestMetadata("idea/testData/inspectionsLocal/useExpressionBody")
    @TestDataPath("$PROJECT_ROOT")
    @RunWith(JUnit3RunnerWithInners.class)
				`@@ -0,0 +1 @@`
				`org.jetbrains.kotlin.idea.inspections.UnnecessaryVariableInspection`