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 { 21 namespace tidy { 22 namespace abseil { 23 24 StringFindStartswithCheck::StringFindStartswithCheck(StringRef Name, 25 ClangTidyContext *Context) 26 : ClangTidyCheck(Name, Context), 27 StringLikeClasses(utils::options::parseStringList( 28 Options.get("StringLikeClasses", "::std::basic_string"))), 29 IncludeInserter(Options.getLocalOrGlobal("IncludeStyle", 30 utils::IncludeSorter::IS_LLVM), 31 areDiagsSelfContained()), 32 AbseilStringsMatchHeader( 33 Options.get("AbseilStringsMatchHeader", "absl/strings/match.h")) {} 34 35 void StringFindStartswithCheck::registerMatchers(MatchFinder *Finder) { 36 auto ZeroLiteral = integerLiteral(equals(0)); 37 auto StringClassMatcher = cxxRecordDecl(hasAnyName(SmallVector<StringRef, 4>( 38 StringLikeClasses.begin(), StringLikeClasses.end()))); 39 auto StringType = hasUnqualifiedDesugaredType( 40 recordType(hasDeclaration(StringClassMatcher))); 41 42 auto StringFind = cxxMemberCallExpr( 43 // .find()-call on a string... 44 callee(cxxMethodDecl(hasName("find")).bind("findfun")), 45 on(hasType(StringType)), 46 // ... with some search expression ... 47 hasArgument(0, expr().bind("needle")), 48 // ... and either "0" as second argument or the default argument (also 0). 49 anyOf(hasArgument(1, ZeroLiteral), hasArgument(1, cxxDefaultArgExpr()))); 50 51 Finder->addMatcher( 52 // Match [=!]= with a zero on one side and a string.find on the other. 53 binaryOperator( 54 hasAnyOperatorName("==", "!="), 55 hasOperands(ignoringParenImpCasts(ZeroLiteral), 56 ignoringParenImpCasts(StringFind.bind("findexpr")))) 57 .bind("expr"), 58 this); 59 60 auto StringRFind = cxxMemberCallExpr( 61 // .rfind()-call on a string... 62 callee(cxxMethodDecl(hasName("rfind")).bind("findfun")), 63 on(hasType(StringType)), 64 // ... with some search expression ... 65 hasArgument(0, expr().bind("needle")), 66 // ... and "0" as second argument. 67 hasArgument(1, ZeroLiteral)); 68 69 Finder->addMatcher( 70 // Match [=!]= with either a zero or npos on one side and a string.rfind 71 // on the other. 72 binaryOperator( 73 hasAnyOperatorName("==", "!="), 74 hasOperands(ignoringParenImpCasts(ZeroLiteral), 75 ignoringParenImpCasts(StringRFind.bind("findexpr")))) 76 .bind("expr"), 77 this); 78 } 79 80 void StringFindStartswithCheck::check(const MatchFinder::MatchResult &Result) { 81 const ASTContext &Context = *Result.Context; 82 const SourceManager &Source = Context.getSourceManager(); 83 84 // Extract matching (sub)expressions 85 const auto *ComparisonExpr = Result.Nodes.getNodeAs<BinaryOperator>("expr"); 86 assert(ComparisonExpr != nullptr); 87 const auto *Needle = Result.Nodes.getNodeAs<Expr>("needle"); 88 assert(Needle != nullptr); 89 const Expr *Haystack = Result.Nodes.getNodeAs<CXXMemberCallExpr>("findexpr") 90 ->getImplicitObjectArgument(); 91 assert(Haystack != nullptr); 92 const CXXMethodDecl *FindFun = 93 Result.Nodes.getNodeAs<CXXMethodDecl>("findfun"); 94 assert(FindFun != nullptr); 95 96 bool Rev = FindFun->getName().contains("rfind"); 97 98 if (ComparisonExpr->getBeginLoc().isMacroID()) 99 return; 100 101 // Get the source code blocks (as characters) for both the string object 102 // and the search expression 103 const StringRef NeedleExprCode = Lexer::getSourceText( 104 CharSourceRange::getTokenRange(Needle->getSourceRange()), Source, 105 Context.getLangOpts()); 106 const StringRef HaystackExprCode = Lexer::getSourceText( 107 CharSourceRange::getTokenRange(Haystack->getSourceRange()), Source, 108 Context.getLangOpts()); 109 110 // Create the StartsWith string, negating if comparison was "!=". 111 bool Neg = ComparisonExpr->getOpcode() == BO_NE; 112 113 // Create the warning message and a FixIt hint replacing the original expr. 114 auto Diagnostic = 115 diag(ComparisonExpr->getBeginLoc(), 116 "use %select{absl::StartsWith|!absl::StartsWith}0 " 117 "instead of %select{find()|rfind()}1 %select{==|!=}0 0") 118 << Neg << Rev; 119 120 Diagnostic << FixItHint::CreateReplacement( 121 ComparisonExpr->getSourceRange(), 122 ((Neg ? "!absl::StartsWith(" : "absl::StartsWith(") + HaystackExprCode + 123 ", " + NeedleExprCode + ")") 124 .str()); 125 126 // Create a preprocessor #include FixIt hint (createIncludeInsertion checks 127 // whether this already exists). 128 Diagnostic << IncludeInserter.createIncludeInsertion( 129 Source.getFileID(ComparisonExpr->getBeginLoc()), 130 AbseilStringsMatchHeader); 131 } 132 133 void StringFindStartswithCheck::registerPPCallbacks( 134 const SourceManager &SM, Preprocessor *PP, Preprocessor *ModuleExpanderPP) { 135 IncludeInserter.registerPreprocessor(PP); 136 } 137 138 void StringFindStartswithCheck::storeOptions( 139 ClangTidyOptions::OptionMap &Opts) { 140 Options.store(Opts, "StringLikeClasses", 141 utils::options::serializeStringList(StringLikeClasses)); 142 Options.store(Opts, "IncludeStyle", IncludeInserter.getStyle()); 143 Options.store(Opts, "AbseilStringsMatchHeader", AbseilStringsMatchHeader); 144 } 145 146 } // namespace abseil 147 } // namespace tidy 148 } // namespace clang 149