clang-tools-extra/clang-tidy/bugprone/ParentVirtualCallCheck.cpp

   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
  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
  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
  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.
  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
  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
  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