| 1 | //===--- InefficientStringConcatenationCheck.cpp - clang-tidy--------------===// |
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| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | |
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| 9 | #include "InefficientStringConcatenationCheck.h" |
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| 10 | #include "clang/ASTMatchers/ASTMatchFinder.h" |
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| 11 | |
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| 12 | using namespace clang::ast_matchers; |
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| 13 | |
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| 14 | namespace clang::tidy::performance { |
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| 15 | |
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| 16 | void InefficientStringConcatenationCheck::storeOptions( |
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| 17 | ClangTidyOptions::OptionMap &Opts) { |
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| 18 | Options.store(Options&: Opts, LocalName: "StrictMode" , Value: StrictMode); |
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| 19 | } |
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| 20 | |
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| 21 | InefficientStringConcatenationCheck::InefficientStringConcatenationCheck( |
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| 22 | StringRef Name, ClangTidyContext *Context) |
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| 23 | : ClangTidyCheck(Name, Context), |
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| 24 | StrictMode(Options.getLocalOrGlobal(LocalName: "StrictMode" , Default: false)) {} |
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| 25 | |
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| 26 | void InefficientStringConcatenationCheck::registerMatchers( |
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| 27 | MatchFinder *Finder) { |
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| 28 | const auto BasicStringType = |
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| 29 | hasType(InnerMatcher: qualType(hasUnqualifiedDesugaredType(InnerMatcher: recordType( |
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| 30 | hasDeclaration(InnerMatcher: cxxRecordDecl(hasName(Name: "::std::basic_string" ))))))); |
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| 31 | |
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| 32 | const auto BasicStringPlusOperator = cxxOperatorCallExpr( |
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| 33 | hasOverloadedOperatorName(Name: "+" ), |
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| 34 | hasAnyArgument(InnerMatcher: ignoringImpCasts(InnerMatcher: declRefExpr(BasicStringType)))); |
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| 35 | |
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| 36 | const auto PlusOperator = |
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| 37 | cxxOperatorCallExpr( |
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| 38 | hasOverloadedOperatorName(Name: "+" ), |
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| 39 | hasAnyArgument(InnerMatcher: ignoringImpCasts(InnerMatcher: declRefExpr(BasicStringType))), |
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| 40 | hasDescendant(BasicStringPlusOperator)) |
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| 41 | .bind(ID: "plusOperator" ); |
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| 42 | |
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| 43 | const auto AssignOperator = cxxOperatorCallExpr( |
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| 44 | hasOverloadedOperatorName(Name: "=" ), |
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| 45 | hasArgument(N: 0, InnerMatcher: declRefExpr(BasicStringType, |
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| 46 | hasDeclaration(InnerMatcher: decl().bind(ID: "lhsStrT" ))) |
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| 47 | .bind(ID: "lhsStr" )), |
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| 48 | hasArgument(N: 1, InnerMatcher: stmt(hasDescendant(declRefExpr( |
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| 49 | hasDeclaration(InnerMatcher: decl(equalsBoundNode(ID: "lhsStrT" ))))))), |
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| 50 | hasDescendant(BasicStringPlusOperator)); |
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| 51 | |
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| 52 | if (StrictMode) { |
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| 53 | Finder->addMatcher(NodeMatch: cxxOperatorCallExpr(anyOf(AssignOperator, PlusOperator)), |
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| 54 | Action: this); |
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| 55 | } else { |
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| 56 | Finder->addMatcher( |
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| 57 | NodeMatch: cxxOperatorCallExpr(anyOf(AssignOperator, PlusOperator), |
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| 58 | hasAncestor(stmt(anyOf(cxxForRangeStmt(), |
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| 59 | whileStmt(), forStmt())))), |
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| 60 | Action: this); |
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| 61 | } |
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| 62 | } |
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| 63 | |
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| 64 | void InefficientStringConcatenationCheck::check( |
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| 65 | const MatchFinder::MatchResult &Result) { |
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| 66 | const auto *LhsStr = Result.Nodes.getNodeAs<DeclRefExpr>(ID: "lhsStr" ); |
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| 67 | const auto *PlusOperator = |
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| 68 | Result.Nodes.getNodeAs<CXXOperatorCallExpr>(ID: "plusOperator" ); |
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| 69 | const char *DiagMsg = |
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| 70 | "string concatenation results in allocation of unnecessary temporary " |
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| 71 | "strings; consider using 'operator+=' or 'string::append()' instead" ; |
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| 72 | |
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| 73 | if (LhsStr) |
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| 74 | diag(LhsStr->getExprLoc(), DiagMsg); |
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| 75 | else if (PlusOperator) |
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| 76 | diag(Loc: PlusOperator->getExprLoc(), Description: DiagMsg); |
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| 77 | } |
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| 78 | |
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| 79 | } // namespace clang::tidy::performance |
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| 80 | |
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