clang-tools 19.0.0git
ExplicitConstructorCheck.cpp
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1//===--- ExplicitConstructorCheck.cpp - clang-tidy ------------------------===//
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
10#include "clang/AST/ASTContext.h"
11#include "clang/ASTMatchers/ASTMatchFinder.h"
12#include "clang/ASTMatchers/ASTMatchers.h"
13#include "clang/Lex/Lexer.h"
14
15using namespace clang::ast_matchers;
16
17namespace clang::tidy::google {
18
20 Finder->addMatcher(
21 cxxConstructorDecl(unless(anyOf(isImplicit(), // Compiler-generated.
22 isDeleted(), isInstantiated())))
23 .bind("ctor"),
24 this);
25 Finder->addMatcher(
26 cxxConversionDecl(unless(anyOf(isExplicit(), // Already marked explicit.
27 isImplicit(), // Compiler-generated.
28 isDeleted(), isInstantiated())))
29
30 .bind("conversion"),
31 this);
32}
33
34// Looks for the token matching the predicate and returns the range of the found
35// token including trailing whitespace.
36static SourceRange findToken(const SourceManager &Sources,
37 const LangOptions &LangOpts,
38 SourceLocation StartLoc, SourceLocation EndLoc,
39 bool (*Pred)(const Token &)) {
40 if (StartLoc.isMacroID() || EndLoc.isMacroID())
41 return {};
42 FileID File = Sources.getFileID(Sources.getSpellingLoc(StartLoc));
43 StringRef Buf = Sources.getBufferData(File);
44 const char *StartChar = Sources.getCharacterData(StartLoc);
45 Lexer Lex(StartLoc, LangOpts, StartChar, StartChar, Buf.end());
46 Lex.SetCommentRetentionState(true);
47 Token Tok;
48 do {
49 Lex.LexFromRawLexer(Tok);
50 if (Pred(Tok)) {
51 Token NextTok;
52 Lex.LexFromRawLexer(NextTok);
53 return {Tok.getLocation(), NextTok.getLocation()};
54 }
55 } while (Tok.isNot(tok::eof) && Tok.getLocation() < EndLoc);
56
57 return {};
58}
59
60static bool declIsStdInitializerList(const NamedDecl *D) {
61 // First use the fast getName() method to avoid unnecessary calls to the
62 // slow getQualifiedNameAsString().
63 return D->getName() == "initializer_list" &&
64 D->getQualifiedNameAsString() == "std::initializer_list";
65}
66
67static bool isStdInitializerList(QualType Type) {
68 Type = Type.getCanonicalType();
69 if (const auto *TS = Type->getAs<TemplateSpecializationType>()) {
70 if (const TemplateDecl *TD = TS->getTemplateName().getAsTemplateDecl())
71 return declIsStdInitializerList(TD);
72 }
73 if (const auto *RT = Type->getAs<RecordType>()) {
74 if (const auto *Specialization =
75 dyn_cast<ClassTemplateSpecializationDecl>(RT->getDecl()))
76 return declIsStdInitializerList(Specialization->getSpecializedTemplate());
77 }
78 return false;
79}
80
81void ExplicitConstructorCheck::check(const MatchFinder::MatchResult &Result) {
82 constexpr char WarningMessage[] =
83 "%0 must be marked explicit to avoid unintentional implicit conversions";
84
85 if (const auto *Conversion =
86 Result.Nodes.getNodeAs<CXXConversionDecl>("conversion")) {
87 if (Conversion->isOutOfLine())
88 return;
89 SourceLocation Loc = Conversion->getLocation();
90 // Ignore all macros until we learn to ignore specific ones (e.g. used in
91 // gmock to define matchers).
92 if (Loc.isMacroID())
93 return;
94 diag(Loc, WarningMessage)
95 << Conversion << FixItHint::CreateInsertion(Loc, "explicit ");
96 return;
97 }
98
99 const auto *Ctor = Result.Nodes.getNodeAs<CXXConstructorDecl>("ctor");
100 if (Ctor->isOutOfLine() || Ctor->getNumParams() == 0 ||
101 Ctor->getMinRequiredArguments() > 1)
102 return;
103
104 bool TakesInitializerList = isStdInitializerList(
105 Ctor->getParamDecl(0)->getType().getNonReferenceType());
106 if (Ctor->isExplicit() &&
107 (Ctor->isCopyOrMoveConstructor() || TakesInitializerList)) {
108 auto IsKwExplicit = [](const Token &Tok) {
109 return Tok.is(tok::raw_identifier) &&
110 Tok.getRawIdentifier() == "explicit";
111 };
112 SourceRange ExplicitTokenRange =
113 findToken(*Result.SourceManager, getLangOpts(),
114 Ctor->getOuterLocStart(), Ctor->getEndLoc(), IsKwExplicit);
115 StringRef ConstructorDescription;
116 if (Ctor->isMoveConstructor())
117 ConstructorDescription = "move";
118 else if (Ctor->isCopyConstructor())
119 ConstructorDescription = "copy";
120 else
121 ConstructorDescription = "initializer-list";
122
123 auto Diag = diag(Ctor->getLocation(),
124 "%0 constructor should not be declared explicit")
125 << ConstructorDescription;
126 if (ExplicitTokenRange.isValid()) {
127 Diag << FixItHint::CreateRemoval(
128 CharSourceRange::getCharRange(ExplicitTokenRange));
129 }
130 return;
131 }
132
133 if (Ctor->isExplicit() || Ctor->isCopyOrMoveConstructor() ||
134 TakesInitializerList)
135 return;
136
137 bool SingleArgument =
138 Ctor->getNumParams() == 1 && !Ctor->getParamDecl(0)->isParameterPack();
139 SourceLocation Loc = Ctor->getLocation();
140 diag(Loc, WarningMessage)
141 << (SingleArgument
142 ? "single-argument constructors"
143 : "constructors that are callable with a single argument")
144 << FixItHint::CreateInsertion(Loc, "explicit ");
145}
146
147} // namespace clang::tidy::google
NodeType Type
SourceLocation Loc
DiagnosticBuilder diag(SourceLocation Loc, StringRef Description, DiagnosticIDs::Level Level=DiagnosticIDs::Warning)
Add a diagnostic with the check's name.
const LangOptions & getLangOpts() const
Returns the language options from the context.
void registerMatchers(ast_matchers::MatchFinder *Finder) override
Override this to register AST matchers with Finder.
void check(const ast_matchers::MatchFinder::MatchResult &Result) override
ClangTidyChecks that register ASTMatchers should do the actual work in here.
static bool isStdInitializerList(QualType Type)
static SourceRange findToken(const SourceManager &Sources, const LangOptions &LangOpts, SourceLocation StartLoc, SourceLocation EndLoc, bool(*Pred)(const Token &))
static bool declIsStdInitializerList(const NamedDecl *D)