clang-tools-extra/clang-tidy/readability/StringCompareCheck.cpp

   1 //===-- StringCompareCheck.cpp - clang-tidy--------------------------------===//
   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-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "StringCompareCheck.h"
  10 #include "../utils/OptionsUtils.h"
  11 #include "clang/AST/ASTContext.h"
  12 #include "clang/ASTMatchers/ASTMatchFinder.h"
  13 #include "clang/ASTMatchers/ASTMatchers.h"
  14 #include "clang/Tooling/FixIt.h"
  15 #include "llvm/ADT/StringRef.h"
  16
  17 using namespace clang::ast_matchers;
  18 namespace optutils = clang::tidy::utils::options;
  19
  20 namespace clang::tidy::readability {
  21
  22 static const StringRef CompareMessage = "do not use 'compare' to test equality "
  23                                         "of strings; use the string equality "
  24                                         "operator instead";
  25
  26 static const StringRef DefaultStringLikeClasses = "::std::basic_string;"
  27                                                   "::std::basic_string_view";
  28
  29 StringCompareCheck::StringCompareCheck(StringRef Name,
  30                                        ClangTidyContext *Context)
  31     : ClangTidyCheck(Name, Context),
  32       StringLikeClasses(optutils::parseStringList(
  33           Options.get("StringLikeClasses", DefaultStringLikeClasses))) {}
  34
  35 void StringCompareCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
  36   Options.store(Opts, "StringLikeClasses",
  37                 optutils::serializeStringList(StringLikeClasses));
  38 }
  39
  40 void StringCompareCheck::registerMatchers(MatchFinder *Finder) {
  41   if (StringLikeClasses.empty()) {
  42     return;
  43   }
  44   const auto StrCompare = cxxMemberCallExpr(
  45       callee(cxxMethodDecl(hasName("compare"), ofClass(cxxRecordDecl(hasAnyName(
  46                                                    StringLikeClasses))))),
  47       hasArgument(0, expr().bind("str2")), argumentCountIs(1),
  48       callee(memberExpr().bind("str1")));
  49
  50   // First and second case: cast str.compare(str) to boolean.
  51   Finder->addMatcher(
  52       traverse(TK_AsIs,
  53                implicitCastExpr(hasImplicitDestinationType(booleanType()),
  54                                 has(StrCompare))
  55                    .bind("match1")),
  56       this);
  57
  58   // Third and fourth case: str.compare(str) == 0 and str.compare(str) != 0.
  59   Finder->addMatcher(
  60       binaryOperator(hasAnyOperatorName("==", "!="),
  61                      hasOperands(StrCompare.bind("compare"),
  62                                  integerLiteral(equals(0)).bind("zero")))
  63           .bind("match2"),
  64       this);
  65 }
  66
  67 void StringCompareCheck::check(const MatchFinder::MatchResult &Result) {
  68   if (const auto *Matched = Result.Nodes.getNodeAs<Stmt>("match1")) {
  69     diag(Matched->getBeginLoc(), CompareMessage);
  70     return;
  71   }
  72
  73   if (const auto *Matched = Result.Nodes.getNodeAs<Stmt>("match2")) {
  74     const ASTContext &Ctx = *Result.Context;
  75
  76     if (const auto *Zero = Result.Nodes.getNodeAs<Stmt>("zero")) {
  77       const auto *Str1 = Result.Nodes.getNodeAs<MemberExpr>("str1");
  78       const auto *Str2 = Result.Nodes.getNodeAs<Stmt>("str2");
  79       const auto *Compare = Result.Nodes.getNodeAs<Stmt>("compare");
  80
  81       auto Diag = diag(Matched->getBeginLoc(), CompareMessage);
  82
  83       if (Str1->isArrow())
  84         Diag << FixItHint::CreateInsertion(Str1->getBeginLoc(), "*");
  85
  86       Diag << tooling::fixit::createReplacement(*Zero, *Str2, Ctx)
  87            << tooling::fixit::createReplacement(*Compare, *Str1->getBase(),
  88                                                 Ctx);
  89     }
  90   }
  91
  92   // FIXME: Add fixit to fix the code for case one and two (match1).
  93 }
  94
  95 } // namespace clang::tidy::readability