clang-tools  11.0.0
MultipleInheritanceCheck.cpp
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1 //===--- MultipleInheritanceCheck.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 
10 #include "clang/AST/ASTContext.h"
11 #include "clang/ASTMatchers/ASTMatchFinder.h"
12 
13 using namespace clang;
14 using namespace clang::ast_matchers;
15 
16 namespace clang {
17 namespace tidy {
18 namespace fuchsia {
19 
20 namespace {
21 AST_MATCHER(CXXRecordDecl, hasBases) {
22  if (Node.hasDefinition())
23  return Node.getNumBases() > 0;
24  return false;
25 }
26 } // namespace
27 
28 // Adds a node (by name) to the interface map, if it was not present in the map
29 // previously.
30 void MultipleInheritanceCheck::addNodeToInterfaceMap(const CXXRecordDecl *Node,
31  bool isInterface) {
32  assert(Node->getIdentifier());
33  StringRef Name = Node->getIdentifier()->getName();
34  InterfaceMap.insert(std::make_pair(Name, isInterface));
35 }
36 
37 // Returns "true" if the boolean "isInterface" has been set to the
38 // interface status of the current Node. Return "false" if the
39 // interface status for the current node is not yet known.
40 bool MultipleInheritanceCheck::getInterfaceStatus(const CXXRecordDecl *Node,
41  bool &isInterface) const {
42  assert(Node->getIdentifier());
43  StringRef Name = Node->getIdentifier()->getName();
44  llvm::StringMapConstIterator<bool> Pair = InterfaceMap.find(Name);
45  if (Pair == InterfaceMap.end())
46  return false;
47  isInterface = Pair->second;
48  return true;
49 }
50 
51 bool MultipleInheritanceCheck::isCurrentClassInterface(
52  const CXXRecordDecl *Node) const {
53  // Interfaces should have no fields.
54  if (!Node->field_empty()) return false;
55 
56  // Interfaces should have exclusively pure methods.
57  return llvm::none_of(Node->methods(), [](const CXXMethodDecl *M) {
58  return M->isUserProvided() && !M->isPure() && !M->isStatic();
59  });
60 }
61 
62 bool MultipleInheritanceCheck::isInterface(const CXXRecordDecl *Node) {
63  if (!Node->getIdentifier())
64  return false;
65 
66  // Short circuit the lookup if we have analyzed this record before.
67  bool PreviousIsInterfaceResult;
68  if (getInterfaceStatus(Node, PreviousIsInterfaceResult))
69  return PreviousIsInterfaceResult;
70 
71  // To be an interface, all base classes must be interfaces as well.
72  for (const auto &I : Node->bases()) {
73  if (I.isVirtual()) continue;
74  const auto *Ty = I.getType()->getAs<RecordType>();
75  if (!Ty) continue;
76  const RecordDecl *D = Ty->getDecl()->getDefinition();
77  if (!D) continue;
78  const auto *Base = cast<CXXRecordDecl>(D);
79  if (!isInterface(Base)) {
80  addNodeToInterfaceMap(Node, false);
81  return false;
82  }
83  }
84 
85  bool CurrentClassIsInterface = isCurrentClassInterface(Node);
86  addNodeToInterfaceMap(Node, CurrentClassIsInterface);
87  return CurrentClassIsInterface;
88 }
89 
90 void MultipleInheritanceCheck::registerMatchers(MatchFinder *Finder) {
91  // Match declarations which have bases.
92  Finder->addMatcher(
93  cxxRecordDecl(allOf(hasBases(), isDefinition())).bind("decl"), this);
94 }
95 
96 void MultipleInheritanceCheck::check(const MatchFinder::MatchResult &Result) {
97  if (const auto *D = Result.Nodes.getNodeAs<CXXRecordDecl>("decl")) {
98  // Check against map to see if if the class inherits from multiple
99  // concrete classes
100  unsigned NumConcrete = 0;
101  for (const auto &I : D->bases()) {
102  if (I.isVirtual()) continue;
103  const auto *Ty = I.getType()->getAs<RecordType>();
104  if (!Ty) continue;
105  const auto *Base = cast<CXXRecordDecl>(Ty->getDecl()->getDefinition());
106  if (!isInterface(Base)) NumConcrete++;
107  }
108 
109  // Check virtual bases to see if there is more than one concrete
110  // non-virtual base.
111  for (const auto &V : D->vbases()) {
112  const auto *Ty = V.getType()->getAs<RecordType>();
113  if (!Ty) continue;
114  const auto *Base = cast<CXXRecordDecl>(Ty->getDecl()->getDefinition());
115  if (!isInterface(Base)) NumConcrete++;
116  }
117 
118  if (NumConcrete > 1) {
119  diag(D->getBeginLoc(), "inheriting multiple classes that aren't "
120  "pure virtual is discouraged");
121  }
122  }
123 }
124 
125 } // namespace fuchsia
126 } // namespace tidy
127 } // namespace clang
Base
std::unique_ptr< GlobalCompilationDatabase > Base
Definition: GlobalCompilationDatabaseTests.cpp:85
clang::ast_matchers
Definition: AbseilMatcher.h:14
Name
static constexpr llvm::StringLiteral Name
Definition: UppercaseLiteralSuffixCheck.cpp:27
clang::ast_matchers::AST_MATCHER
AST_MATCHER(Expr, isMacroID)
Definition: PreferIsaOrDynCastInConditionalsCheck.cpp:19
clang
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
Definition: ApplyReplacements.h:27
MultipleInheritanceCheck.h