clang-tools-extra/clang-tidy/performance/FasterStringFindCheck.cpp

   1 //===--- FasterStringFindCheck.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 "FasterStringFindCheck.h"
  10 #include "../utils/OptionsUtils.h"
  11 #include "clang/AST/ASTContext.h"
  12 #include "clang/ASTMatchers/ASTMatchFinder.h"
  13 #include "llvm/Support/raw_ostream.h"
  14 #include <optional>
  15
  16 using namespace clang::ast_matchers;
  17
  18 namespace clang::tidy::performance {
  19
  20 namespace {
  21
  22 std::optional<std::string> makeCharacterLiteral(const StringLiteral *Literal) {
  23   std::string Result;
  24   {
  25     llvm::raw_string_ostream OS(Result);
  26     Literal->outputString(OS);
  27   }
  28   // Now replace the " with '.
  29   auto OpenPos = Result.find_first_of('"');
  30   if (OpenPos == std::string::npos)
  31     return std::nullopt;
  32   Result[OpenPos] = '\'';
  33
  34   auto ClosePos = Result.find_last_of('"');
  35   if (ClosePos == std::string::npos)
  36     return std::nullopt;
  37   Result[ClosePos] = '\'';
  38
  39   // "'" is OK, but ''' is not, so add a backslash
  40   if ((ClosePos - OpenPos) == 2 && Result[OpenPos + 1] == '\'')
  41     Result.replace(OpenPos + 1, 1, "\\'");
  42
  43   return Result;
  44 }
  45
  46 AST_MATCHER_FUNCTION(ast_matchers::internal::Matcher<Expr>,
  47                      hasSubstitutedType) {
  48   return hasType(qualType(anyOf(substTemplateTypeParmType(),
  49                                 hasDescendant(substTemplateTypeParmType()))));
  50 }
  51
  52 } // namespace
  53
  54 FasterStringFindCheck::FasterStringFindCheck(StringRef Name,
  55                                              ClangTidyContext *Context)
  56     : ClangTidyCheck(Name, Context),
  57       StringLikeClasses(utils::options::parseStringList(
  58           Options.get("StringLikeClasses",
  59                       "::std::basic_string;::std::basic_string_view"))) {}
  60
  61 void FasterStringFindCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
  62   Options.store(Opts, "StringLikeClasses",
  63                 utils::options::serializeStringList(StringLikeClasses));
  64 }
  65
  66 void FasterStringFindCheck::registerMatchers(MatchFinder *Finder) {
  67   const auto SingleChar =
  68       expr(ignoringParenCasts(stringLiteral(hasSize(1)).bind("literal")));
  69   const auto StringFindFunctions =
  70       hasAnyName("find", "rfind", "find_first_of", "find_first_not_of",
  71                  "find_last_of", "find_last_not_of");
  72
  73   Finder->addMatcher(
  74       cxxMemberCallExpr(
  75           callee(functionDecl(StringFindFunctions).bind("func")),
  76           anyOf(argumentCountIs(1), argumentCountIs(2)),
  77           hasArgument(0, SingleChar),
  78           on(expr(hasType(hasUnqualifiedDesugaredType(recordType(hasDeclaration(
  79                       recordDecl(hasAnyName(StringLikeClasses)))))),
  80                   unless(hasSubstitutedType())))),
  81       this);
  82 }
  83
  84 void FasterStringFindCheck::check(const MatchFinder::MatchResult &Result) {
  85   const auto *Literal = Result.Nodes.getNodeAs<StringLiteral>("literal");
  86   const auto *FindFunc = Result.Nodes.getNodeAs<FunctionDecl>("func");
  87
  88   auto Replacement = makeCharacterLiteral(Literal);
  89   if (!Replacement)
  90     return;
  91
  92   diag(Literal->getBeginLoc(), "%0 called with a string literal consisting of "
  93                                "a single character; consider using the more "
  94                                "effective overload accepting a character")
  95       << FindFunc
  96       << FixItHint::CreateReplacement(
  97              CharSourceRange::getTokenRange(Literal->getBeginLoc(),
  98                                             Literal->getEndLoc()),
  99              *Replacement);
 100 }
 101
 102 } // namespace clang::tidy::performance