1 //===--- ParentVirtualCallCheck.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 "ParentVirtualCallCheck.h"
10 #include "clang/AST/ASTContext.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12 #include "clang/Tooling/FixIt.h"
13 #include "llvm/ADT/STLExtras.h"
14 #include "llvm/ADT/SmallVector.h"
15 #include <algorithm>
16 #include <cctype>
17
18 using namespace clang::ast_matchers;
19
20 namespace clang::tidy::bugprone {
21
22 using BasesVector = llvm::SmallVector<const CXXRecordDecl *, 5>;
23
isParentOf(const CXXRecordDecl & Parent,const CXXRecordDecl & ThisClass)24 static bool isParentOf(const CXXRecordDecl &Parent,
25 const CXXRecordDecl &ThisClass) {
26 if (Parent.getCanonicalDecl() == ThisClass.getCanonicalDecl())
27 return true;
28 const CXXRecordDecl *ParentCanonicalDecl = Parent.getCanonicalDecl();
29 return llvm::any_of(ThisClass.bases(), [=](const CXXBaseSpecifier &Base) {
30 auto *BaseDecl = Base.getType()->getAsCXXRecordDecl();
31 assert(BaseDecl);
32 return ParentCanonicalDecl == BaseDecl->getCanonicalDecl();
33 });
34 }
35
getParentsByGrandParent(const CXXRecordDecl & GrandParent,const CXXRecordDecl & ThisClass,const CXXMethodDecl & MemberDecl)36 static BasesVector getParentsByGrandParent(const CXXRecordDecl &GrandParent,
37 const CXXRecordDecl &ThisClass,
38 const CXXMethodDecl &MemberDecl) {
39 BasesVector Result;
40 for (const auto &Base : ThisClass.bases()) {
41 const auto *BaseDecl = Base.getType()->getAsCXXRecordDecl();
42 const CXXMethodDecl *ActualMemberDecl =
43 MemberDecl.getCorrespondingMethodInClass(BaseDecl);
44 if (!ActualMemberDecl)
45 continue;
46 // TypePtr is the nearest base class to ThisClass between ThisClass and
47 // GrandParent, where MemberDecl is overridden. TypePtr is the class the
48 // check proposes to fix to.
49 const Type *TypePtr = ActualMemberDecl->getThisType().getTypePtr();
50 const CXXRecordDecl *RecordDeclType = TypePtr->getPointeeCXXRecordDecl();
51 assert(RecordDeclType && "TypePtr is not a pointer to CXXRecordDecl!");
52 if (RecordDeclType->getCanonicalDecl()->isDerivedFrom(&GrandParent))
53 Result.emplace_back(RecordDeclType);
54 }
55
56 return Result;
57 }
58
getNameAsString(const NamedDecl * Decl)59 static std::string getNameAsString(const NamedDecl *Decl) {
60 std::string QualName;
61 llvm::raw_string_ostream OS(QualName);
62 PrintingPolicy PP(Decl->getASTContext().getPrintingPolicy());
63 PP.SuppressUnwrittenScope = true;
64 Decl->printQualifiedName(OS, PP);
65 return OS.str();
66 }
67
68 // Returns E as written in the source code. Used to handle 'using' and
69 // 'typedef'ed names of grand-parent classes.
getExprAsString(const clang::Expr & E,clang::ASTContext & AC)70 static std::string getExprAsString(const clang::Expr &E,
71 clang::ASTContext &AC) {
72 std::string Text = tooling::fixit::getText(E, AC).str();
73 llvm::erase_if(Text, [](char C) {
74 return llvm::isSpace(static_cast<unsigned char>(C));
75 });
76 return Text;
77 }
78
registerMatchers(MatchFinder * Finder)79 void ParentVirtualCallCheck::registerMatchers(MatchFinder *Finder) {
80 Finder->addMatcher(
81 traverse(
82 TK_AsIs,
83 cxxMemberCallExpr(
84 callee(memberExpr(hasDescendant(implicitCastExpr(
85 hasImplicitDestinationType(pointsTo(
86 type(anything()).bind("castToType"))),
87 hasSourceExpression(cxxThisExpr(hasType(
88 type(anything()).bind("thisType")))))))
89 .bind("member")),
90 callee(cxxMethodDecl(isVirtual())))),
91 this);
92 }
93
check(const MatchFinder::MatchResult & Result)94 void ParentVirtualCallCheck::check(const MatchFinder::MatchResult &Result) {
95 const auto *Member = Result.Nodes.getNodeAs<MemberExpr>("member");
96 assert(Member);
97
98 if (!Member->getQualifier())
99 return;
100
101 const auto *MemberDecl = cast<CXXMethodDecl>(Member->getMemberDecl());
102
103 const auto *ThisTypePtr = Result.Nodes.getNodeAs<PointerType>("thisType");
104 assert(ThisTypePtr);
105
106 const auto *ThisType = ThisTypePtr->getPointeeCXXRecordDecl();
107 assert(ThisType);
108
109 const auto *CastToTypePtr = Result.Nodes.getNodeAs<Type>("castToType");
110 assert(CastToTypePtr);
111
112 const auto *CastToType = CastToTypePtr->getAsCXXRecordDecl();
113 assert(CastToType);
114
115 if (isParentOf(*CastToType, *ThisType))
116 return;
117
118 const BasesVector Parents =
119 getParentsByGrandParent(*CastToType, *ThisType, *MemberDecl);
120
121 if (Parents.empty())
122 return;
123
124 std::string ParentsStr;
125 ParentsStr.reserve(30 * Parents.size());
126 for (const CXXRecordDecl *Parent : Parents) {
127 if (!ParentsStr.empty())
128 ParentsStr.append(" or ");
129 ParentsStr.append("'").append(getNameAsString(Parent)).append("'");
130 }
131
132 assert(Member->getQualifierLoc().getSourceRange().getBegin().isValid());
133 auto Diag = diag(Member->getQualifierLoc().getSourceRange().getBegin(),
134 "qualified name '%0' refers to a member overridden "
135 "in %plural{1:subclass|:subclasses}1; did you mean %2?")
136 << getExprAsString(*Member, *Result.Context)
137 << static_cast<unsigned>(Parents.size()) << ParentsStr;
138
139 // Propose a fix if there's only one parent class...
140 if (Parents.size() == 1 &&
141 // ...unless parent class is templated
142 !isa<ClassTemplateSpecializationDecl>(Parents.front()))
143 Diag << FixItHint::CreateReplacement(
144 Member->getQualifierLoc().getSourceRange(),
145 getNameAsString(Parents.front()) + "::");
146 }
147
148 } // namespace clang::tidy::bugprone
149