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1 //===--- ExplicitConstructorCheck.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 "ExplicitConstructorCheck.h"
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10 #include "clang/AST/ASTContext.h"
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11 #include "clang/ASTMatchers/ASTMatchFinder.h"
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12 #include "clang/ASTMatchers/ASTMatchers.h"
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13 #include "clang/Lex/Lexer.h"
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14
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15 using namespace clang::ast_matchers;
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16
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252
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17 namespace clang::tidy::google {
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150
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18
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19 void ExplicitConstructorCheck::registerMatchers(MatchFinder *Finder) {
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20 Finder->addMatcher(
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21 cxxConstructorDecl(unless(anyOf(isImplicit(), // Compiler-generated.
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22 isDeleted(), isInstantiated())))
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23 .bind("ctor"),
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24 this);
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25 Finder->addMatcher(
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26 cxxConversionDecl(unless(anyOf(isExplicit(), // Already marked explicit.
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27 isImplicit(), // Compiler-generated.
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28 isDeleted(), isInstantiated())))
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29
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30 .bind("conversion"),
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31 this);
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32 }
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33
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34 // Looks for the token matching the predicate and returns the range of the found
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35 // token including trailing whitespace.
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221
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36 static SourceRange findToken(const SourceManager &Sources,
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150
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37 const LangOptions &LangOpts,
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38 SourceLocation StartLoc, SourceLocation EndLoc,
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39 bool (*Pred)(const Token &)) {
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40 if (StartLoc.isMacroID() || EndLoc.isMacroID())
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41 return SourceRange();
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42 FileID File = Sources.getFileID(Sources.getSpellingLoc(StartLoc));
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43 StringRef Buf = Sources.getBufferData(File);
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44 const char *StartChar = Sources.getCharacterData(StartLoc);
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45 Lexer Lex(StartLoc, LangOpts, StartChar, StartChar, Buf.end());
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46 Lex.SetCommentRetentionState(true);
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47 Token Tok;
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48 do {
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49 Lex.LexFromRawLexer(Tok);
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50 if (Pred(Tok)) {
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51 Token NextTok;
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52 Lex.LexFromRawLexer(NextTok);
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53 return SourceRange(Tok.getLocation(), NextTok.getLocation());
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54 }
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55 } while (Tok.isNot(tok::eof) && Tok.getLocation() < EndLoc);
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56
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57 return SourceRange();
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58 }
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59
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60 static bool declIsStdInitializerList(const NamedDecl *D) {
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61 // First use the fast getName() method to avoid unnecessary calls to the
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62 // slow getQualifiedNameAsString().
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63 return D->getName() == "initializer_list" &&
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64 D->getQualifiedNameAsString() == "std::initializer_list";
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65 }
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66
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67 static bool isStdInitializerList(QualType Type) {
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68 Type = Type.getCanonicalType();
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69 if (const auto *TS = Type->getAs<TemplateSpecializationType>()) {
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70 if (const TemplateDecl *TD = TS->getTemplateName().getAsTemplateDecl())
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71 return declIsStdInitializerList(TD);
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72 }
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73 if (const auto *RT = Type->getAs<RecordType>()) {
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74 if (const auto *Specialization =
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75 dyn_cast<ClassTemplateSpecializationDecl>(RT->getDecl()))
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76 return declIsStdInitializerList(Specialization->getSpecializedTemplate());
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77 }
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78 return false;
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79 }
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80
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81 void ExplicitConstructorCheck::check(const MatchFinder::MatchResult &Result) {
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82 constexpr char WarningMessage[] =
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83 "%0 must be marked explicit to avoid unintentional implicit conversions";
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84
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85 if (const auto *Conversion =
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86 Result.Nodes.getNodeAs<CXXConversionDecl>("conversion")) {
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87 if (Conversion->isOutOfLine())
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88 return;
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89 SourceLocation Loc = Conversion->getLocation();
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90 // Ignore all macros until we learn to ignore specific ones (e.g. used in
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91 // gmock to define matchers).
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92 if (Loc.isMacroID())
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93 return;
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94 diag(Loc, WarningMessage)
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95 << Conversion << FixItHint::CreateInsertion(Loc, "explicit ");
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96 return;
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97 }
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98
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99 const auto *Ctor = Result.Nodes.getNodeAs<CXXConstructorDecl>("ctor");
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100 if (Ctor->isOutOfLine() || Ctor->getNumParams() == 0 ||
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101 Ctor->getMinRequiredArguments() > 1)
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102 return;
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103
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221
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104 bool TakesInitializerList = isStdInitializerList(
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105 Ctor->getParamDecl(0)->getType().getNonReferenceType());
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106 if (Ctor->isExplicit() &&
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221
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107 (Ctor->isCopyOrMoveConstructor() || TakesInitializerList)) {
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108 auto IsKwExplicit = [](const Token &Tok) {
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150
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109 return Tok.is(tok::raw_identifier) &&
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110 Tok.getRawIdentifier() == "explicit";
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111 };
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112 SourceRange ExplicitTokenRange =
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221
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113 findToken(*Result.SourceManager, getLangOpts(),
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114 Ctor->getOuterLocStart(), Ctor->getEndLoc(), IsKwExplicit);
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150
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115 StringRef ConstructorDescription;
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116 if (Ctor->isMoveConstructor())
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117 ConstructorDescription = "move";
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118 else if (Ctor->isCopyConstructor())
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119 ConstructorDescription = "copy";
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120 else
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121 ConstructorDescription = "initializer-list";
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122
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123 auto Diag = diag(Ctor->getLocation(),
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124 "%0 constructor should not be declared explicit")
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125 << ConstructorDescription;
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126 if (ExplicitTokenRange.isValid()) {
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127 Diag << FixItHint::CreateRemoval(
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128 CharSourceRange::getCharRange(ExplicitTokenRange));
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129 }
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130 return;
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131 }
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132
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133 if (Ctor->isExplicit() || Ctor->isCopyOrMoveConstructor() ||
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221
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134 TakesInitializerList)
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150
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135 return;
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136
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137 bool SingleArgument =
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138 Ctor->getNumParams() == 1 && !Ctor->getParamDecl(0)->isParameterPack();
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139 SourceLocation Loc = Ctor->getLocation();
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140 diag(Loc, WarningMessage)
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141 << (SingleArgument
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142 ? "single-argument constructors"
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143 : "constructors that are callable with a single argument")
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144 << FixItHint::CreateInsertion(Loc, "explicit ");
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145 }
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146
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252
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147 } // namespace clang::tidy::google
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