207 lines · cpp
1//===--- CloneChecker.cpp - Clone detection checker -------------*- C++ -*-===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8///9/// \file10/// CloneChecker is a checker that reports clones in the current translation11/// unit.12///13//===----------------------------------------------------------------------===//14 15#include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"16#include "clang/Analysis/CloneDetection.h"17#include "clang/Basic/Diagnostic.h"18#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"19#include "clang/StaticAnalyzer/Core/Checker.h"20#include "clang/StaticAnalyzer/Core/CheckerManager.h"21#include "clang/StaticAnalyzer/Core/PathSensitive/AnalysisManager.h"22#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"23 24using namespace clang;25using namespace ento;26 27namespace {28class CloneChecker29 : public Checker<check::ASTCodeBody, check::EndOfTranslationUnit> {30public:31 // Checker options.32 int MinComplexity;33 bool ReportNormalClones = false;34 StringRef IgnoredFilesPattern;35 36private:37 mutable CloneDetector Detector;38 const BugType BT_Exact{this, "Exact code clone", "Code clone"};39 const BugType BT_Suspicious{this, "Suspicious code clone", "Code clone"};40 41public:42 void checkASTCodeBody(const Decl *D, AnalysisManager &Mgr,43 BugReporter &BR) const;44 45 void checkEndOfTranslationUnit(const TranslationUnitDecl *TU,46 AnalysisManager &Mgr, BugReporter &BR) const;47 48 /// Reports all clones to the user.49 void reportClones(BugReporter &BR, AnalysisManager &Mgr,50 std::vector<CloneDetector::CloneGroup> &CloneGroups) const;51 52 /// Reports only suspicious clones to the user along with information53 /// that explain why they are suspicious.54 void reportSuspiciousClones(55 BugReporter &BR, AnalysisManager &Mgr,56 std::vector<CloneDetector::CloneGroup> &CloneGroups) const;57};58} // end anonymous namespace59 60void CloneChecker::checkASTCodeBody(const Decl *D, AnalysisManager &Mgr,61 BugReporter &BR) const {62 // Every statement that should be included in the search for clones needs to63 // be passed to the CloneDetector.64 Detector.analyzeCodeBody(D);65}66 67void CloneChecker::checkEndOfTranslationUnit(const TranslationUnitDecl *TU,68 AnalysisManager &Mgr,69 BugReporter &BR) const {70 // At this point, every statement in the translation unit has been analyzed by71 // the CloneDetector. The only thing left to do is to report the found clones.72 73 // Let the CloneDetector create a list of clones from all the analyzed74 // statements. We don't filter for matching variable patterns at this point75 // because reportSuspiciousClones() wants to search them for errors.76 std::vector<CloneDetector::CloneGroup> AllCloneGroups;77 78 Detector.findClones(79 AllCloneGroups, FilenamePatternConstraint(IgnoredFilesPattern),80 RecursiveCloneTypeIIHashConstraint(), MinGroupSizeConstraint(2),81 MinComplexityConstraint(MinComplexity),82 RecursiveCloneTypeIIVerifyConstraint(), OnlyLargestCloneConstraint());83 84 reportSuspiciousClones(BR, Mgr, AllCloneGroups);85 86 // We are done for this translation unit unless we also need to report normal87 // clones.88 if (!ReportNormalClones)89 return;90 91 // Now that the suspicious clone detector has checked for pattern errors,92 // we also filter all clones who don't have matching patterns93 CloneDetector::constrainClones(AllCloneGroups,94 MatchingVariablePatternConstraint(),95 MinGroupSizeConstraint(2));96 97 reportClones(BR, Mgr, AllCloneGroups);98}99 100static PathDiagnosticLocation makeLocation(const StmtSequence &S,101 AnalysisManager &Mgr) {102 ASTContext &ACtx = Mgr.getASTContext();103 return PathDiagnosticLocation::createBegin(104 S.front(), ACtx.getSourceManager(),105 Mgr.getAnalysisDeclContext(ACtx.getTranslationUnitDecl()));106}107 108void CloneChecker::reportClones(109 BugReporter &BR, AnalysisManager &Mgr,110 std::vector<CloneDetector::CloneGroup> &CloneGroups) const {111 for (const CloneDetector::CloneGroup &Group : CloneGroups) {112 // We group the clones by printing the first as a warning and all others113 // as a note.114 auto R = std::make_unique<BasicBugReport>(115 BT_Exact, "Duplicate code detected", makeLocation(Group.front(), Mgr));116 R->addRange(Group.front().getSourceRange());117 118 for (unsigned i = 1; i < Group.size(); ++i)119 R->addNote("Similar code here", makeLocation(Group[i], Mgr),120 Group[i].getSourceRange());121 BR.emitReport(std::move(R));122 }123}124 125void CloneChecker::reportSuspiciousClones(126 BugReporter &BR, AnalysisManager &Mgr,127 std::vector<CloneDetector::CloneGroup> &CloneGroups) const {128 std::vector<VariablePattern::SuspiciousClonePair> Pairs;129 130 for (const CloneDetector::CloneGroup &Group : CloneGroups) {131 for (unsigned i = 0; i < Group.size(); ++i) {132 VariablePattern PatternA(Group[i]);133 134 for (unsigned j = i + 1; j < Group.size(); ++j) {135 VariablePattern PatternB(Group[j]);136 137 VariablePattern::SuspiciousClonePair ClonePair;138 // For now, we only report clones which break the variable pattern just139 // once because multiple differences in a pattern are an indicator that140 // those differences are maybe intended (e.g. because it's actually a141 // different algorithm).142 // FIXME: In very big clones even multiple variables can be unintended,143 // so replacing this number with a percentage could better handle such144 // cases. On the other hand it could increase the false-positive rate145 // for all clones if the percentage is too high.146 if (PatternA.countPatternDifferences(PatternB, &ClonePair) == 1) {147 Pairs.push_back(ClonePair);148 break;149 }150 }151 }152 }153 154 ASTContext &ACtx = BR.getContext();155 SourceManager &SM = ACtx.getSourceManager();156 AnalysisDeclContext *ADC =157 Mgr.getAnalysisDeclContext(ACtx.getTranslationUnitDecl());158 159 for (VariablePattern::SuspiciousClonePair &Pair : Pairs) {160 // FIXME: We are ignoring the suggestions currently, because they are161 // only 50% accurate (even if the second suggestion is unavailable),162 // which may confuse the user.163 // Think how to perform more accurate suggestions?164 165 auto R = std::make_unique<BasicBugReport>(166 BT_Suspicious,167 "Potential copy-paste error; did you really mean to use '" +168 Pair.FirstCloneInfo.Variable->getNameAsString() + "' here?",169 PathDiagnosticLocation::createBegin(Pair.FirstCloneInfo.Mention, SM,170 ADC));171 R->addRange(Pair.FirstCloneInfo.Mention->getSourceRange());172 173 R->addNote("Similar code using '" +174 Pair.SecondCloneInfo.Variable->getNameAsString() + "' here",175 PathDiagnosticLocation::createBegin(Pair.SecondCloneInfo.Mention,176 SM, ADC),177 Pair.SecondCloneInfo.Mention->getSourceRange());178 179 BR.emitReport(std::move(R));180 }181}182 183//===----------------------------------------------------------------------===//184// Register CloneChecker185//===----------------------------------------------------------------------===//186 187void ento::registerCloneChecker(CheckerManager &Mgr) {188 auto *Checker = Mgr.registerChecker<CloneChecker>();189 190 Checker->MinComplexity = Mgr.getAnalyzerOptions().getCheckerIntegerOption(191 Checker, "MinimumCloneComplexity");192 193 if (Checker->MinComplexity < 0)194 Mgr.reportInvalidCheckerOptionValue(195 Checker, "MinimumCloneComplexity", "a non-negative value");196 197 Checker->ReportNormalClones = Mgr.getAnalyzerOptions().getCheckerBooleanOption(198 Checker, "ReportNormalClones");199 200 Checker->IgnoredFilesPattern = Mgr.getAnalyzerOptions()201 .getCheckerStringOption(Checker, "IgnoredFilesPattern");202}203 204bool ento::shouldRegisterCloneChecker(const CheckerManager &mgr) {205 return true;206}207