1 //===--- MoveConstructorInitCheck.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
9 #include "MoveConstructorInitCheck.h"
10 #include "../utils/Matchers.h"
11 #include "clang/AST/ASTContext.h"
12 #include "clang/ASTMatchers/ASTMatchFinder.h"
13 #include "clang/Frontend/CompilerInstance.h"
14 #include "clang/Lex/Lexer.h"
15 #include "clang/Lex/Preprocessor.h"
16
17 using namespace clang::ast_matchers;
18
19 namespace clang {
20 namespace tidy {
21 namespace performance {
22
MoveConstructorInitCheck(StringRef Name,ClangTidyContext * Context)23 MoveConstructorInitCheck::MoveConstructorInitCheck(StringRef Name,
24 ClangTidyContext *Context)
25 : ClangTidyCheck(Name, Context),
26 Inserter(Options.getLocalOrGlobal("IncludeStyle",
27 utils::IncludeSorter::IS_LLVM)) {}
28
registerMatchers(MatchFinder * Finder)29 void MoveConstructorInitCheck::registerMatchers(MatchFinder *Finder) {
30 Finder->addMatcher(
31 traverse(ast_type_traits::TK_AsIs,
32 cxxConstructorDecl(
33 unless(isImplicit()), isMoveConstructor(),
34 hasAnyConstructorInitializer(
35 cxxCtorInitializer(
36 withInitializer(cxxConstructExpr(hasDeclaration(
37 cxxConstructorDecl(isCopyConstructor())
38 .bind("ctor")))))
39 .bind("move-init")))),
40 this);
41 }
42
check(const MatchFinder::MatchResult & Result)43 void MoveConstructorInitCheck::check(const MatchFinder::MatchResult &Result) {
44 const auto *CopyCtor = Result.Nodes.getNodeAs<CXXConstructorDecl>("ctor");
45 const auto *Initializer =
46 Result.Nodes.getNodeAs<CXXCtorInitializer>("move-init");
47
48 // Do not diagnose if the expression used to perform the initialization is a
49 // trivially-copyable type.
50 QualType QT = Initializer->getInit()->getType();
51 if (QT.isTriviallyCopyableType(*Result.Context))
52 return;
53
54 if (QT.isConstQualified())
55 return;
56
57 const auto *RD = QT->getAsCXXRecordDecl();
58 if (RD && RD->isTriviallyCopyable())
59 return;
60
61 // Diagnose when the class type has a move constructor available, but the
62 // ctor-initializer uses the copy constructor instead.
63 const CXXConstructorDecl *Candidate = nullptr;
64 for (const auto *Ctor : CopyCtor->getParent()->ctors()) {
65 if (Ctor->isMoveConstructor() && Ctor->getAccess() <= AS_protected &&
66 !Ctor->isDeleted()) {
67 // The type has a move constructor that is at least accessible to the
68 // initializer.
69 //
70 // FIXME: Determine whether the move constructor is a viable candidate
71 // for the ctor-initializer, perhaps provide a fixit that suggests
72 // using std::move().
73 Candidate = Ctor;
74 break;
75 }
76 }
77
78 if (Candidate) {
79 // There's a move constructor candidate that the caller probably intended
80 // to call instead.
81 diag(Initializer->getSourceLocation(),
82 "move constructor initializes %0 by calling a copy constructor")
83 << (Initializer->isBaseInitializer() ? "base class" : "class member");
84 diag(CopyCtor->getLocation(), "copy constructor being called",
85 DiagnosticIDs::Note);
86 diag(Candidate->getLocation(), "candidate move constructor here",
87 DiagnosticIDs::Note);
88 }
89 }
90
registerPPCallbacks(const SourceManager & SM,Preprocessor * PP,Preprocessor * ModuleExpanderPP)91 void MoveConstructorInitCheck::registerPPCallbacks(
92 const SourceManager &SM, Preprocessor *PP, Preprocessor *ModuleExpanderPP) {
93 Inserter.registerPreprocessor(PP);
94 }
95
storeOptions(ClangTidyOptions::OptionMap & Opts)96 void MoveConstructorInitCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
97 Options.store(Opts, "IncludeStyle", Inserter.getStyle());
98 }
99
100 } // namespace performance
101 } // namespace tidy
102 } // namespace clang
103