| /* |
| * Copyright (C) 2014 The Android Open Source Project |
| * |
| * 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 com.android.tools.lint.checks; |
| |
| import static com.android.tools.lint.detector.api.LintUtils.isNullLiteral; |
| |
| import com.android.annotations.NonNull; |
| import com.android.annotations.Nullable; |
| import com.android.tools.lint.detector.api.Category; |
| import com.android.tools.lint.detector.api.Detector; |
| import com.android.tools.lint.detector.api.Detector.JavaPsiScanner; |
| import com.android.tools.lint.detector.api.Implementation; |
| import com.android.tools.lint.detector.api.Issue; |
| import com.android.tools.lint.detector.api.JavaContext; |
| import com.android.tools.lint.detector.api.Scope; |
| import com.android.tools.lint.detector.api.Severity; |
| import com.intellij.psi.JavaElementVisitor; |
| import com.intellij.psi.PsiAssertStatement; |
| import com.intellij.psi.PsiBinaryExpression; |
| import com.intellij.psi.PsiElement; |
| import com.intellij.psi.PsiExpression; |
| import com.intellij.psi.PsiLiteral; |
| |
| import java.util.Collections; |
| import java.util.List; |
| |
| /** |
| * Looks for assertion usages. |
| */ |
| public class AssertDetector extends Detector implements JavaPsiScanner { |
| /** Using assertions */ |
| public static final Issue ISSUE = Issue.create( |
| "Assert", //$NON-NLS-1$ |
| "Assertions", |
| |
| "Assertions are not checked at runtime. There are ways to request that they be used " + |
| "by Dalvik (`adb shell setprop debug.assert 1`), but the property is ignored in " + |
| "many places and can not be relied upon. Instead, perform conditional checking " + |
| "inside `if (BuildConfig.DEBUG) { }` blocks. That constant is a static final boolean " + |
| "which is true in debug builds and false in release builds, and the Java compiler " + |
| "completely removes all code inside the if-body from the app.\n" + |
| "\n" + |
| "For example, you can replace `assert speed > 0` with " + |
| "`if (BuildConfig.DEBUG && !(speed > 0)) { throw new AssertionError() }`.\n" + |
| "\n" + |
| "(Note: This lint check does not flag assertions purely asserting nullness or " + |
| "non-nullness; these are typically more intended for tools usage than runtime " + |
| "checks.)", |
| |
| Category.CORRECTNESS, |
| 6, |
| Severity.WARNING, |
| new Implementation( |
| AssertDetector.class, |
| Scope.JAVA_FILE_SCOPE)) |
| .addMoreInfo( |
| "https://code.google.com/p/android/issues/detail?id=65183"); //$NON-NLS-1$ |
| |
| /** Constructs a new {@link AssertDetector} check */ |
| public AssertDetector() { |
| } |
| |
| // ---- Implements JavaScanner ---- |
| |
| |
| @Override |
| public List<Class<? extends PsiElement>> getApplicablePsiTypes() { |
| return Collections.<Class<? extends PsiElement>>singletonList(PsiAssertStatement.class); |
| } |
| |
| @Nullable |
| @Override |
| public JavaElementVisitor createPsiVisitor(@NonNull final JavaContext context) { |
| if (!context.getMainProject().isAndroidProject()) { |
| return null; |
| } |
| |
| return new JavaElementVisitor() { |
| @Override |
| public void visitAssertStatement(PsiAssertStatement node) { |
| PsiExpression assertion = node.getAssertCondition(); |
| // Allow "assert true"; it's basically a no-op |
| if (assertion instanceof PsiLiteral) { |
| Object value = ((PsiLiteral)assertion).getValue(); |
| if (Boolean.TRUE.equals(value)) { |
| return; |
| } |
| } else { |
| // Allow assertions of the form "assert foo != null" because they are often used |
| // to make statements to tools about known nullness properties. For example, |
| // findViewById() may technically return null in some cases, but a developer |
| // may know that it won't be when it's called correctly, so the assertion helps |
| // to clear nullness warnings. |
| if (isNullCheck(assertion)) { |
| return; |
| } |
| } |
| String message |
| = "Assertions are unreliable. Use `BuildConfig.DEBUG` conditional checks instead."; |
| context.report(ISSUE, node, context.getLocation(node), message); |
| } |
| }; |
| } |
| |
| /** |
| * Checks whether the given expression is purely a non-null check, e.g. it will return |
| * true for expressions like "a != null" and "a != null && b != null" and |
| * "b == null || c != null". |
| */ |
| private static boolean isNullCheck(PsiExpression expression) { |
| if (expression instanceof PsiBinaryExpression) { |
| PsiBinaryExpression binExp = (PsiBinaryExpression) expression; |
| PsiExpression lOperand = binExp.getLOperand(); |
| PsiExpression rOperand = binExp.getROperand(); |
| if (isNullLiteral(lOperand) || isNullLiteral(rOperand)) { |
| return true; |
| } else { |
| return isNullCheck(lOperand) && isNullCheck(rOperand); |
| } |
| } else { |
| return false; |
| } |
| } |
| } |