1 //===--- CopyConstructorInitCheck.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 "CopyConstructorInitCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12 #include "clang/Lex/Lexer.h"
13
14 using namespace clang::ast_matchers;
15
16 namespace clang::tidy::bugprone {
17
registerMatchers(MatchFinder * Finder)18 void CopyConstructorInitCheck::registerMatchers(MatchFinder *Finder) {
19 // In the future this might be extended to move constructors?
20 Finder->addMatcher(
21 cxxConstructorDecl(
22 isCopyConstructor(),
23 hasAnyConstructorInitializer(cxxCtorInitializer(
24 isBaseInitializer(),
25 withInitializer(cxxConstructExpr(hasDeclaration(
26 cxxConstructorDecl(isDefaultConstructor())))))),
27 unless(isInstantiated()))
28 .bind("ctor"),
29 this);
30 }
31
check(const MatchFinder::MatchResult & Result)32 void CopyConstructorInitCheck::check(const MatchFinder::MatchResult &Result) {
33 const auto *Ctor = Result.Nodes.getNodeAs<CXXConstructorDecl>("ctor");
34 std::string ParamName = Ctor->getParamDecl(0)->getNameAsString();
35
36 // We want only one warning (and FixIt) for each ctor.
37 std::string FixItInitList;
38 bool HasRelevantBaseInit = false;
39 bool ShouldNotDoFixit = false;
40 bool HasWrittenInitializer = false;
41 SmallVector<FixItHint, 2> SafeFixIts;
42 for (const auto *Init : Ctor->inits()) {
43 bool CtorInitIsWritten = Init->isWritten();
44 HasWrittenInitializer = HasWrittenInitializer || CtorInitIsWritten;
45 if (!Init->isBaseInitializer())
46 continue;
47 const Type *BaseType = Init->getBaseClass();
48 // Do not do fixits if there is a type alias involved or one of the bases
49 // are explicitly initialized. In the latter case we not do fixits to avoid
50 // -Wreorder warnings.
51 if (const auto *TempSpecTy = dyn_cast<TemplateSpecializationType>(BaseType))
52 ShouldNotDoFixit = ShouldNotDoFixit || TempSpecTy->isTypeAlias();
53 ShouldNotDoFixit = ShouldNotDoFixit || isa<TypedefType>(BaseType);
54 ShouldNotDoFixit = ShouldNotDoFixit || CtorInitIsWritten;
55 const CXXRecordDecl *BaseClass =
56 BaseType->getAsCXXRecordDecl()->getDefinition();
57 if (BaseClass->field_empty() &&
58 BaseClass->forallBases(
59 [](const CXXRecordDecl *Class) { return Class->field_empty(); }))
60 continue;
61 bool NonCopyableBase = false;
62 for (const auto *Ctor : BaseClass->ctors()) {
63 if (Ctor->isCopyConstructor() &&
64 (Ctor->getAccess() == AS_private || Ctor->isDeleted())) {
65 NonCopyableBase = true;
66 break;
67 }
68 }
69 if (NonCopyableBase)
70 continue;
71 const auto *CExpr = dyn_cast<CXXConstructExpr>(Init->getInit());
72 if (!CExpr || !CExpr->getConstructor()->isDefaultConstructor())
73 continue;
74 HasRelevantBaseInit = true;
75 if (CtorInitIsWritten) {
76 if (!ParamName.empty())
77 SafeFixIts.push_back(
78 FixItHint::CreateInsertion(CExpr->getEndLoc(), ParamName));
79 } else {
80 if (Init->getSourceLocation().isMacroID() ||
81 Ctor->getLocation().isMacroID() || ShouldNotDoFixit)
82 break;
83 FixItInitList += BaseClass->getNameAsString();
84 FixItInitList += "(" + ParamName + "), ";
85 }
86 }
87 if (!HasRelevantBaseInit)
88 return;
89
90 auto Diag = diag(Ctor->getLocation(),
91 "calling a base constructor other than the copy constructor")
92 << SafeFixIts;
93
94 if (FixItInitList.empty() || ParamName.empty() || ShouldNotDoFixit)
95 return;
96
97 std::string FixItMsg{FixItInitList.substr(0, FixItInitList.size() - 2)};
98 SourceLocation FixItLoc;
99 // There is no initialization list in this constructor.
100 if (!HasWrittenInitializer) {
101 FixItLoc = Ctor->getBody()->getBeginLoc();
102 FixItMsg = " : " + FixItMsg;
103 } else {
104 // We apply the missing ctors at the beginning of the initialization list.
105 FixItLoc = (*Ctor->init_begin())->getSourceLocation();
106 FixItMsg += ',';
107 }
108 FixItMsg += ' ';
109
110 Diag << FixItHint::CreateInsertion(FixItLoc, FixItMsg);
111 }
112
113 } // namespace clang::tidy::bugprone
114