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