clang-tools  3.8.0
ExplicitConstructorCheck.cpp
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1 //===--- ExplicitConstructorCheck.cpp - clang-tidy ------------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
11 #include "clang/AST/ASTContext.h"
12 #include "clang/ASTMatchers/ASTMatchFinder.h"
13 #include "clang/ASTMatchers/ASTMatchers.h"
14 #include "clang/Lex/Lexer.h"
15 
16 using namespace clang::ast_matchers;
17 
18 namespace clang {
19 namespace tidy {
20 namespace google {
21 
22 void ExplicitConstructorCheck::registerMatchers(MatchFinder *Finder) {
23  // Only register the matchers for C++; the functionality currently does not
24  // provide any benefit to other languages, despite being benign.
25  if (getLangOpts().CPlusPlus)
26  Finder->addMatcher(
27  cxxConstructorDecl(unless(isInstantiated())).bind("ctor"), this);
28 }
29 
30 // Looks for the token matching the predicate and returns the range of the found
31 // token including trailing whitespace.
32 static SourceRange FindToken(const SourceManager &Sources, LangOptions LangOpts,
33  SourceLocation StartLoc, SourceLocation EndLoc,
34  bool (*Pred)(const Token &)) {
35  if (StartLoc.isMacroID() || EndLoc.isMacroID())
36  return SourceRange();
37  FileID File = Sources.getFileID(Sources.getSpellingLoc(StartLoc));
38  StringRef Buf = Sources.getBufferData(File);
39  const char *StartChar = Sources.getCharacterData(StartLoc);
40  Lexer Lex(StartLoc, LangOpts, StartChar, StartChar, Buf.end());
41  Lex.SetCommentRetentionState(true);
42  Token Tok;
43  do {
44  Lex.LexFromRawLexer(Tok);
45  if (Pred(Tok)) {
46  Token NextTok;
47  Lex.LexFromRawLexer(NextTok);
48  return SourceRange(Tok.getLocation(), NextTok.getLocation());
49  }
50  } while (Tok.isNot(tok::eof) && Tok.getLocation() < EndLoc);
51 
52  return SourceRange();
53 }
54 
55 static bool declIsStdInitializerList(const NamedDecl *D) {
56  // First use the fast getName() method to avoid unnecessary calls to the
57  // slow getQualifiedNameAsString().
58  return D->getName() == "initializer_list" &&
59  D->getQualifiedNameAsString() == "std::initializer_list";
60 }
61 
62 static bool isStdInitializerList(QualType Type) {
63  Type = Type.getCanonicalType();
64  if (const auto *TS = Type->getAs<TemplateSpecializationType>()) {
65  if (const TemplateDecl *TD = TS->getTemplateName().getAsTemplateDecl())
66  return declIsStdInitializerList(TD);
67  }
68  if (const auto *RT = Type->getAs<RecordType>()) {
69  if (const auto *Specialization =
70  dyn_cast<ClassTemplateSpecializationDecl>(RT->getDecl()))
71  return declIsStdInitializerList(Specialization->getSpecializedTemplate());
72  }
73  return false;
74 }
75 
76 void ExplicitConstructorCheck::check(const MatchFinder::MatchResult &Result) {
77  const CXXConstructorDecl *Ctor =
78  Result.Nodes.getNodeAs<CXXConstructorDecl>("ctor");
79  // Do not be confused: isExplicit means 'explicit' keyword is present,
80  // isImplicit means that it's a compiler-generated constructor.
81  if (Ctor->isOutOfLine() || Ctor->isImplicit() || Ctor->isDeleted() ||
82  Ctor->getNumParams() == 0 || Ctor->getMinRequiredArguments() > 1)
83  return;
84 
85  bool takesInitializerList = isStdInitializerList(
86  Ctor->getParamDecl(0)->getType().getNonReferenceType());
87  if (Ctor->isExplicit() &&
88  (Ctor->isCopyOrMoveConstructor() || takesInitializerList)) {
89  auto isKWExplicit = [](const Token &Tok) {
90  return Tok.is(tok::raw_identifier) &&
91  Tok.getRawIdentifier() == "explicit";
92  };
93  SourceRange ExplicitTokenRange =
94  FindToken(*Result.SourceManager, Result.Context->getLangOpts(),
95  Ctor->getOuterLocStart(), Ctor->getLocEnd(), isKWExplicit);
96  StringRef ConstructorDescription;
97  if (Ctor->isMoveConstructor())
98  ConstructorDescription = "move";
99  else if (Ctor->isCopyConstructor())
100  ConstructorDescription = "copy";
101  else
102  ConstructorDescription = "initializer-list";
103 
104  DiagnosticBuilder Diag =
105  diag(Ctor->getLocation(),
106  "%0 constructor should not be declared explicit")
107  << ConstructorDescription;
108  if (ExplicitTokenRange.isValid()) {
109  Diag << FixItHint::CreateRemoval(
110  CharSourceRange::getCharRange(ExplicitTokenRange));
111  }
112  return;
113  }
114 
115  if (Ctor->isExplicit() || Ctor->isCopyOrMoveConstructor() ||
116  takesInitializerList)
117  return;
118 
119  bool SingleArgument =
120  Ctor->getNumParams() == 1 && !Ctor->getParamDecl(0)->isParameterPack();
121  SourceLocation Loc = Ctor->getLocation();
122  diag(Loc,
123  "%0 must be marked explicit to avoid unintentional implicit conversions")
124  << (SingleArgument
125  ? "single-argument constructors"
126  : "constructors that are callable with a single argument")
127  << FixItHint::CreateInsertion(Loc, "explicit ");
128 }
129 
130 } // namespace google
131 } // namespace tidy
132 } // namespace clang
static SourceRange FindToken(const SourceManager &Sources, LangOptions LangOpts, SourceLocation StartLoc, SourceLocation EndLoc, bool(*Pred)(const Token &))
SourceLocation Loc
'#' location in the include directive
static bool isStdInitializerList(QualType Type)
LangOptions LangOpts
Definition: ClangTidy.cpp:168
std::unique_ptr< ast_matchers::MatchFinder > Finder
Definition: ClangTidy.cpp:188
HeaderHandle File
static bool declIsStdInitializerList(const NamedDecl *D)
const NamedDecl * Result
Definition: USRFinder.cpp:121