1 //===--- StringFindStartswithCheck.cc - clang-tidy---------------*- 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-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #include "StringFindStartswithCheck.h" 10 11 #include "../utils/OptionsUtils.h" 12 #include "clang/AST/ASTContext.h" 13 #include "clang/ASTMatchers/ASTMatchers.h" 14 #include "clang/Frontend/CompilerInstance.h" 15 #include "clang/Lex/Lexer.h" 16 #include "clang/Lex/Preprocessor.h" 17 18 using namespace clang::ast_matchers; 19 20 namespace clang::tidy::abseil { 21 22 StringFindStartswithCheck::StringFindStartswithCheck(StringRef Name, 23 ClangTidyContext *Context) 24 : ClangTidyCheck(Name, Context), 25 StringLikeClasses(utils::options::parseStringList( 26 Options.get("StringLikeClasses", "::std::basic_string"))), 27 IncludeInserter(Options.getLocalOrGlobal("IncludeStyle", 28 utils::IncludeSorter::IS_LLVM), 29 areDiagsSelfContained()), 30 AbseilStringsMatchHeader( 31 Options.get("AbseilStringsMatchHeader", "absl/strings/match.h")) {} 32 33 void StringFindStartswithCheck::registerMatchers(MatchFinder *Finder) { 34 auto ZeroLiteral = integerLiteral(equals(0)); 35 auto StringClassMatcher = cxxRecordDecl(hasAnyName(StringLikeClasses)); 36 auto StringType = hasUnqualifiedDesugaredType( 37 recordType(hasDeclaration(StringClassMatcher))); 38 39 auto StringFind = cxxMemberCallExpr( 40 // .find()-call on a string... 41 callee(cxxMethodDecl(hasName("find")).bind("findfun")), 42 on(hasType(StringType)), 43 // ... with some search expression ... 44 hasArgument(0, expr().bind("needle")), 45 // ... and either "0" as second argument or the default argument (also 0). 46 anyOf(hasArgument(1, ZeroLiteral), hasArgument(1, cxxDefaultArgExpr()))); 47 48 Finder->addMatcher( 49 // Match [=!]= with a zero on one side and a string.find on the other. 50 binaryOperator( 51 hasAnyOperatorName("==", "!="), 52 hasOperands(ignoringParenImpCasts(ZeroLiteral), 53 ignoringParenImpCasts(StringFind.bind("findexpr")))) 54 .bind("expr"), 55 this); 56 57 auto StringRFind = cxxMemberCallExpr( 58 // .rfind()-call on a string... 59 callee(cxxMethodDecl(hasName("rfind")).bind("findfun")), 60 on(hasType(StringType)), 61 // ... with some search expression ... 62 hasArgument(0, expr().bind("needle")), 63 // ... and "0" as second argument. 64 hasArgument(1, ZeroLiteral)); 65 66 Finder->addMatcher( 67 // Match [=!]= with either a zero or npos on one side and a string.rfind 68 // on the other. 69 binaryOperator( 70 hasAnyOperatorName("==", "!="), 71 hasOperands(ignoringParenImpCasts(ZeroLiteral), 72 ignoringParenImpCasts(StringRFind.bind("findexpr")))) 73 .bind("expr"), 74 this); 75 } 76 77 void StringFindStartswithCheck::check(const MatchFinder::MatchResult &Result) { 78 const ASTContext &Context = *Result.Context; 79 const SourceManager &Source = Context.getSourceManager(); 80 81 // Extract matching (sub)expressions 82 const auto *ComparisonExpr = Result.Nodes.getNodeAs<BinaryOperator>("expr"); 83 assert(ComparisonExpr != nullptr); 84 const auto *Needle = Result.Nodes.getNodeAs<Expr>("needle"); 85 assert(Needle != nullptr); 86 const Expr *Haystack = Result.Nodes.getNodeAs<CXXMemberCallExpr>("findexpr") 87 ->getImplicitObjectArgument(); 88 assert(Haystack != nullptr); 89 const auto *FindFun = Result.Nodes.getNodeAs<CXXMethodDecl>("findfun"); 90 assert(FindFun != nullptr); 91 92 bool Rev = FindFun->getName().contains("rfind"); 93 94 if (ComparisonExpr->getBeginLoc().isMacroID()) 95 return; 96 97 // Get the source code blocks (as characters) for both the string object 98 // and the search expression 99 const StringRef NeedleExprCode = Lexer::getSourceText( 100 CharSourceRange::getTokenRange(Needle->getSourceRange()), Source, 101 Context.getLangOpts()); 102 const StringRef HaystackExprCode = Lexer::getSourceText( 103 CharSourceRange::getTokenRange(Haystack->getSourceRange()), Source, 104 Context.getLangOpts()); 105 106 // Create the StartsWith string, negating if comparison was "!=". 107 bool Neg = ComparisonExpr->getOpcode() == BO_NE; 108 109 // Create the warning message and a FixIt hint replacing the original expr. 110 auto Diagnostic = 111 diag(ComparisonExpr->getBeginLoc(), 112 "use %select{absl::StartsWith|!absl::StartsWith}0 " 113 "instead of %select{find()|rfind()}1 %select{==|!=}0 0") 114 << Neg << Rev; 115 116 Diagnostic << FixItHint::CreateReplacement( 117 ComparisonExpr->getSourceRange(), 118 ((Neg ? "!absl::StartsWith(" : "absl::StartsWith(") + HaystackExprCode + 119 ", " + NeedleExprCode + ")") 120 .str()); 121 122 // Create a preprocessor #include FixIt hint (createIncludeInsertion checks 123 // whether this already exists). 124 Diagnostic << IncludeInserter.createIncludeInsertion( 125 Source.getFileID(ComparisonExpr->getBeginLoc()), 126 AbseilStringsMatchHeader); 127 } 128 129 void StringFindStartswithCheck::registerPPCallbacks( 130 const SourceManager &SM, Preprocessor *PP, Preprocessor *ModuleExpanderPP) { 131 IncludeInserter.registerPreprocessor(PP); 132 } 133 134 void StringFindStartswithCheck::storeOptions( 135 ClangTidyOptions::OptionMap &Opts) { 136 Options.store(Opts, "StringLikeClasses", 137 utils::options::serializeStringList(StringLikeClasses)); 138 Options.store(Opts, "IncludeStyle", IncludeInserter.getStyle()); 139 Options.store(Opts, "AbseilStringsMatchHeader", AbseilStringsMatchHeader); 140 } 141 142 } // namespace clang::tidy::abseil 143