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 "clang/AST/ASTContext.h"
11#include "clang/ASTMatchers/ASTMatchFinder.h"
12
13using namespace clang::ast_matchers;
14
15namespace clang::tidy::performance {
16
17MoveConstructorInitCheck::MoveConstructorInitCheck(StringRef Name,
18 ClangTidyContext *Context)
19 : ClangTidyCheck(Name, Context) {}
20
21void MoveConstructorInitCheck::registerMatchers(MatchFinder *Finder) {
22 Finder->addMatcher(
23 NodeMatch: traverse(TK: TK_AsIs,
24 InnerMatcher: cxxConstructorDecl(
25 unless(isImplicit()), isMoveConstructor(),
26 hasAnyConstructorInitializer(
27 InnerMatcher: cxxCtorInitializer(
28 withInitializer(InnerMatcher: cxxConstructExpr(hasDeclaration(
29 InnerMatcher: cxxConstructorDecl(isCopyConstructor())
30 .bind(ID: "ctor")))))
31 .bind(ID: "move-init")))),
32 Action: this);
33}
34
35void MoveConstructorInitCheck::check(const MatchFinder::MatchResult &Result) {
36 const auto *CopyCtor = Result.Nodes.getNodeAs<CXXConstructorDecl>(ID: "ctor");
37 const auto *Initializer =
38 Result.Nodes.getNodeAs<CXXCtorInitializer>(ID: "move-init");
39
40 // Do not diagnose if the expression used to perform the initialization is a
41 // trivially-copyable type.
42 QualType QT = Initializer->getInit()->getType();
43 if (QT.isTriviallyCopyableType(Context: *Result.Context))
44 return;
45
46 if (QT.isConstQualified())
47 return;
48
49 const auto *RD = QT->getAsCXXRecordDecl();
50 if (RD && RD->isTriviallyCopyable())
51 return;
52
53 // Diagnose when the class type has a move constructor available, but the
54 // ctor-initializer uses the copy constructor instead.
55 const CXXConstructorDecl *Candidate = nullptr;
56 for (const auto *Ctor : CopyCtor->getParent()->ctors()) {
57 if (Ctor->isMoveConstructor() && Ctor->getAccess() <= AS_protected &&
58 !Ctor->isDeleted()) {
59 // The type has a move constructor that is at least accessible to the
60 // initializer.
61 //
62 // FIXME: Determine whether the move constructor is a viable candidate
63 // for the ctor-initializer, perhaps provide a fix-it that suggests
64 // using std::move().
65 Candidate = Ctor;
66 break;
67 }
68 }
69
70 if (Candidate) {
71 // There's a move constructor candidate that the caller probably intended
72 // to call instead.
73 diag(Loc: Initializer->getSourceLocation(),
74 Description: "move constructor initializes %select{class member|base class}0 by "
75 "calling a copy constructor")
76 << Initializer->isBaseInitializer();
77 diag(CopyCtor->getLocation(), "copy constructor being called",
78 DiagnosticIDs::Note);
79 diag(Candidate->getLocation(), "candidate move constructor here",
80 DiagnosticIDs::Note);
81 }
82}
83
84} // namespace clang::tidy::performance
85

source code of clang-tools-extra/clang-tidy/performance/MoveConstructorInitCheck.cpp