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 {
17 namespace tidy {
18 namespace bugprone {
19
registerMatchers(MatchFinder * Finder)20 void CopyConstructorInitCheck::registerMatchers(MatchFinder *Finder) {
21 // In the future this might be extended to move constructors?
22 Finder->addMatcher(
23 cxxConstructorDecl(
24 isCopyConstructor(),
25 hasAnyConstructorInitializer(cxxCtorInitializer(
26 isBaseInitializer(),
27 withInitializer(cxxConstructExpr(hasDeclaration(
28 cxxConstructorDecl(isDefaultConstructor())))))),
29 unless(isInstantiated()))
30 .bind("ctor"),
31 this);
32 }
33
check(const MatchFinder::MatchResult & Result)34 void CopyConstructorInitCheck::check(const MatchFinder::MatchResult &Result) {
35 const auto *Ctor = Result.Nodes.getNodeAs<CXXConstructorDecl>("ctor");
36 std::string ParamName = Ctor->getParamDecl(0)->getNameAsString();
37
38 // We want only one warning (and FixIt) for each ctor.
39 std::string FixItInitList;
40 bool HasRelevantBaseInit = false;
41 bool ShouldNotDoFixit = false;
42 bool HasWrittenInitializer = false;
43 SmallVector<FixItHint, 2> SafeFixIts;
44 for (const auto *Init : Ctor->inits()) {
45 bool CtorInitIsWritten = Init->isWritten();
46 HasWrittenInitializer = HasWrittenInitializer || CtorInitIsWritten;
47 if (!Init->isBaseInitializer())
48 continue;
49 const Type *BaseType = Init->getBaseClass();
50 // Do not do fixits if there is a type alias involved or one of the bases
51 // are explicitly initialized. In the latter case we not do fixits to avoid
52 // -Wreorder warnings.
53 if (const auto *TempSpecTy = dyn_cast<TemplateSpecializationType>(BaseType))
54 ShouldNotDoFixit = ShouldNotDoFixit || TempSpecTy->isTypeAlias();
55 ShouldNotDoFixit = ShouldNotDoFixit || isa<TypedefType>(BaseType);
56 ShouldNotDoFixit = ShouldNotDoFixit || CtorInitIsWritten;
57 const CXXRecordDecl *BaseClass =
58 BaseType->getAsCXXRecordDecl()->getDefinition();
59 if (BaseClass->field_empty() &&
60 BaseClass->forallBases(
61 [](const CXXRecordDecl *Class) { return Class->field_empty(); }))
62 continue;
63 bool NonCopyableBase = false;
64 for (const auto *Ctor : BaseClass->ctors()) {
65 if (Ctor->isCopyConstructor() &&
66 (Ctor->getAccess() == AS_private || Ctor->isDeleted())) {
67 NonCopyableBase = true;
68 break;
69 }
70 }
71 if (NonCopyableBase)
72 continue;
73 const auto *CExpr = dyn_cast<CXXConstructExpr>(Init->getInit());
74 if (!CExpr || !CExpr->getConstructor()->isDefaultConstructor())
75 continue;
76 HasRelevantBaseInit = true;
77 if (CtorInitIsWritten) {
78 if (!ParamName.empty())
79 SafeFixIts.push_back(
80 FixItHint::CreateInsertion(CExpr->getEndLoc(), ParamName));
81 } else {
82 if (Init->getSourceLocation().isMacroID() ||
83 Ctor->getLocation().isMacroID() || ShouldNotDoFixit)
84 break;
85 FixItInitList += BaseClass->getNameAsString();
86 FixItInitList += "(" + ParamName + "), ";
87 }
88 }
89 if (!HasRelevantBaseInit)
90 return;
91
92 auto Diag = diag(Ctor->getLocation(),
93 "calling a base constructor other than the copy constructor")
94 << SafeFixIts;
95
96 if (FixItInitList.empty() || ParamName.empty() || ShouldNotDoFixit)
97 return;
98
99 std::string FixItMsg{FixItInitList.substr(0, FixItInitList.size() - 2)};
100 SourceLocation FixItLoc;
101 // There is no initialization list in this constructor.
102 if (!HasWrittenInitializer) {
103 FixItLoc = Ctor->getBody()->getBeginLoc();
104 FixItMsg = " : " + FixItMsg;
105 } else {
106 // We apply the missing ctors at the beginning of the initialization list.
107 FixItLoc = (*Ctor->init_begin())->getSourceLocation();
108 FixItMsg += ',';
109 }
110 FixItMsg += ' ';
111
112 Diag << FixItHint::CreateInsertion(FixItLoc, FixItMsg);
113 }
114
115 } // namespace bugprone
116 } // namespace tidy
117 } // namespace clang
118