clang-tools  10.0.0
ReorderFieldsAction.cpp
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1 //===-- tools/extra/clang-reorder-fields/ReorderFieldsAction.cpp -*- C++ -*-===//
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 /// \file
10 /// This file contains the definition of the
11 /// ReorderFieldsAction::newASTConsumer method
12 ///
13 //===----------------------------------------------------------------------===//
14 
15 #include "ReorderFieldsAction.h"
16 #include "clang/AST/AST.h"
17 #include "clang/AST/ASTConsumer.h"
18 #include "clang/AST/ASTContext.h"
19 #include "clang/AST/Decl.h"
20 #include "clang/AST/RecursiveASTVisitor.h"
21 #include "clang/ASTMatchers/ASTMatchFinder.h"
22 #include "clang/Lex/Lexer.h"
23 #include "clang/Tooling/Refactoring.h"
24 #include "llvm/ADT/SetVector.h"
25 #include <algorithm>
26 #include <string>
27 
28 namespace clang {
29 namespace reorder_fields {
30 using namespace clang::ast_matchers;
31 using llvm::SmallSetVector;
32 
33 /// Finds the definition of a record by name.
34 ///
35 /// \returns nullptr if the name is ambiguous or not found.
36 static const RecordDecl *findDefinition(StringRef RecordName,
37  ASTContext &Context) {
38  auto Results =
39  match(recordDecl(hasName(RecordName), isDefinition()).bind("recordDecl"),
40  Context);
41  if (Results.empty()) {
42  llvm::errs() << "Definition of " << RecordName << " not found\n";
43  return nullptr;
44  }
45  if (Results.size() > 1) {
46  llvm::errs() << "The name " << RecordName
47  << " is ambiguous, several definitions found\n";
48  return nullptr;
49  }
50  return selectFirst<RecordDecl>("recordDecl", Results);
51 }
52 
53 /// Calculates the new order of fields.
54 ///
55 /// \returns empty vector if the list of fields doesn't match the definition.
56 static SmallVector<unsigned, 4>
57 getNewFieldsOrder(const RecordDecl *Definition,
58  ArrayRef<std::string> DesiredFieldsOrder) {
59  assert(Definition && "Definition is null");
60 
61  llvm::StringMap<unsigned> NameToIndex;
62  for (const auto *Field : Definition->fields())
63  NameToIndex[Field->getName()] = Field->getFieldIndex();
64 
65  if (DesiredFieldsOrder.size() != NameToIndex.size()) {
66  llvm::errs() << "Number of provided fields doesn't match definition.\n";
67  return {};
68  }
69  SmallVector<unsigned, 4> NewFieldsOrder;
70  for (const auto &Name : DesiredFieldsOrder) {
71  if (!NameToIndex.count(Name)) {
72  llvm::errs() << "Field " << Name << " not found in definition.\n";
73  return {};
74  }
75  NewFieldsOrder.push_back(NameToIndex[Name]);
76  }
77  assert(NewFieldsOrder.size() == NameToIndex.size());
78  return NewFieldsOrder;
79 }
80 
81 // FIXME: error-handling
82 /// Replaces one range of source code by another.
83 static void
84 addReplacement(SourceRange Old, SourceRange New, const ASTContext &Context,
85  std::map<std::string, tooling::Replacements> &Replacements) {
86  StringRef NewText =
87  Lexer::getSourceText(CharSourceRange::getTokenRange(New),
88  Context.getSourceManager(), Context.getLangOpts());
89  tooling::Replacement R(Context.getSourceManager(),
90  CharSourceRange::getTokenRange(Old), NewText,
91  Context.getLangOpts());
92  consumeError(Replacements[R.getFilePath()].add(R));
93 }
94 
95 /// Find all member fields used in the given init-list initializer expr
96 /// that belong to the same record
97 ///
98 /// \returns a set of field declarations, empty if none were present
99 static SmallSetVector<FieldDecl *, 1>
100 findMembersUsedInInitExpr(const CXXCtorInitializer *Initializer,
101  ASTContext &Context) {
102  SmallSetVector<FieldDecl *, 1> Results;
103  // Note that this does not pick up member fields of base classes since
104  // for those accesses Sema::PerformObjectMemberConversion always inserts an
105  // UncheckedDerivedToBase ImplicitCastExpr between the this expr and the
106  // object expression
107  auto FoundExprs =
108  match(findAll(memberExpr(hasObjectExpression(cxxThisExpr())).bind("ME")),
109  *Initializer->getInit(), Context);
110  for (BoundNodes &BN : FoundExprs)
111  if (auto *MemExpr = BN.getNodeAs<MemberExpr>("ME"))
112  if (auto *FD = dyn_cast<FieldDecl>(MemExpr->getMemberDecl()))
113  Results.insert(FD);
114  return Results;
115 }
116 
117 /// Reorders fields in the definition of a struct/class.
118 ///
119 /// At the moment reodering of fields with
120 /// different accesses (public/protected/private) is not supported.
121 /// \returns true on success.
123  const RecordDecl *Definition, ArrayRef<unsigned> NewFieldsOrder,
124  const ASTContext &Context,
125  std::map<std::string, tooling::Replacements> &Replacements) {
126  assert(Definition && "Definition is null");
127 
128  SmallVector<const FieldDecl *, 10> Fields;
129  for (const auto *Field : Definition->fields())
130  Fields.push_back(Field);
131 
132  // Check that the permutation of the fields doesn't change the accesses
133  for (const auto *Field : Definition->fields()) {
134  const auto FieldIndex = Field->getFieldIndex();
135  if (Field->getAccess() != Fields[NewFieldsOrder[FieldIndex]]->getAccess()) {
136  llvm::errs() << "Currently reodering of fields with different accesses "
137  "is not supported\n";
138  return false;
139  }
140  }
141 
142  for (const auto *Field : Definition->fields()) {
143  const auto FieldIndex = Field->getFieldIndex();
144  if (FieldIndex == NewFieldsOrder[FieldIndex])
145  continue;
146  addReplacement(Field->getSourceRange(),
147  Fields[NewFieldsOrder[FieldIndex]]->getSourceRange(),
148  Context, Replacements);
149  }
150  return true;
151 }
152 
153 /// Reorders initializers in a C++ struct/class constructor.
154 ///
155 /// A constructor can have initializers for an arbitrary subset of the class's
156 /// fields. Thus, we need to ensure that we reorder just the initializers that
157 /// are present.
159  const CXXConstructorDecl *CtorDecl, ArrayRef<unsigned> NewFieldsOrder,
160  ASTContext &Context,
161  std::map<std::string, tooling::Replacements> &Replacements) {
162  assert(CtorDecl && "Constructor declaration is null");
163  if (CtorDecl->isImplicit() || CtorDecl->getNumCtorInitializers() <= 1)
164  return;
165 
166  // The method FunctionDecl::isThisDeclarationADefinition returns false
167  // for a defaulted function unless that function has been implicitly defined.
168  // Thus this assert needs to be after the previous checks.
169  assert(CtorDecl->isThisDeclarationADefinition() && "Not a definition");
170 
171  SmallVector<unsigned, 10> NewFieldsPositions(NewFieldsOrder.size());
172  for (unsigned i = 0, e = NewFieldsOrder.size(); i < e; ++i)
173  NewFieldsPositions[NewFieldsOrder[i]] = i;
174 
175  SmallVector<const CXXCtorInitializer *, 10> OldWrittenInitializersOrder;
176  SmallVector<const CXXCtorInitializer *, 10> NewWrittenInitializersOrder;
177  for (const auto *Initializer : CtorDecl->inits()) {
178  if (!Initializer->isMemberInitializer() || !Initializer->isWritten())
179  continue;
180 
181  // Warn if this reordering violates initialization expr dependencies.
182  const FieldDecl *ThisM = Initializer->getMember();
183  const auto UsedMembers = findMembersUsedInInitExpr(Initializer, Context);
184  for (const FieldDecl *UM : UsedMembers) {
185  if (NewFieldsPositions[UM->getFieldIndex()] >
186  NewFieldsPositions[ThisM->getFieldIndex()]) {
187  DiagnosticsEngine &DiagEngine = Context.getDiagnostics();
188  auto Description = ("reordering field " + UM->getName() + " after " +
189  ThisM->getName() + " makes " + UM->getName() +
190  " uninitialized when used in init expression")
191  .str();
192  unsigned ID = DiagEngine.getDiagnosticIDs()->getCustomDiagID(
193  DiagnosticIDs::Warning, Description);
194  DiagEngine.Report(Initializer->getSourceLocation(), ID);
195  }
196  }
197 
198  OldWrittenInitializersOrder.push_back(Initializer);
199  NewWrittenInitializersOrder.push_back(Initializer);
200  }
201  auto ByFieldNewPosition = [&](const CXXCtorInitializer *LHS,
202  const CXXCtorInitializer *RHS) {
203  assert(LHS && RHS);
204  return NewFieldsPositions[LHS->getMember()->getFieldIndex()] <
205  NewFieldsPositions[RHS->getMember()->getFieldIndex()];
206  };
207  std::sort(std::begin(NewWrittenInitializersOrder),
208  std::end(NewWrittenInitializersOrder), ByFieldNewPosition);
209  assert(OldWrittenInitializersOrder.size() ==
210  NewWrittenInitializersOrder.size());
211  for (unsigned i = 0, e = NewWrittenInitializersOrder.size(); i < e; ++i)
212  if (OldWrittenInitializersOrder[i] != NewWrittenInitializersOrder[i])
213  addReplacement(OldWrittenInitializersOrder[i]->getSourceRange(),
214  NewWrittenInitializersOrder[i]->getSourceRange(), Context,
215  Replacements);
216 }
217 
218 /// Reorders initializers in the brace initialization of an aggregate.
219 ///
220 /// At the moment partial initialization is not supported.
221 /// \returns true on success
223  const InitListExpr *InitListEx, ArrayRef<unsigned> NewFieldsOrder,
224  const ASTContext &Context,
225  std::map<std::string, tooling::Replacements> &Replacements) {
226  assert(InitListEx && "Init list expression is null");
227  // We care only about InitListExprs which originate from source code.
228  // Implicit InitListExprs are created by the semantic analyzer.
229  if (!InitListEx->isExplicit())
230  return true;
231  // The method InitListExpr::getSyntacticForm may return nullptr indicating
232  // that the current initializer list also serves as its syntactic form.
233  if (const auto *SyntacticForm = InitListEx->getSyntacticForm())
234  InitListEx = SyntacticForm;
235  // If there are no initializers we do not need to change anything.
236  if (!InitListEx->getNumInits())
237  return true;
238  if (InitListEx->getNumInits() != NewFieldsOrder.size()) {
239  llvm::errs() << "Currently only full initialization is supported\n";
240  return false;
241  }
242  for (unsigned i = 0, e = InitListEx->getNumInits(); i < e; ++i)
243  if (i != NewFieldsOrder[i])
244  addReplacement(InitListEx->getInit(i)->getSourceRange(),
245  InitListEx->getInit(NewFieldsOrder[i])->getSourceRange(),
246  Context, Replacements);
247  return true;
248 }
249 
250 namespace {
251 class ReorderingConsumer : public ASTConsumer {
252  StringRef RecordName;
253  ArrayRef<std::string> DesiredFieldsOrder;
254  std::map<std::string, tooling::Replacements> &Replacements;
255 
256 public:
257  ReorderingConsumer(StringRef RecordName,
258  ArrayRef<std::string> DesiredFieldsOrder,
259  std::map<std::string, tooling::Replacements> &Replacements)
260  : RecordName(RecordName), DesiredFieldsOrder(DesiredFieldsOrder),
261  Replacements(Replacements) {}
262 
263  ReorderingConsumer(const ReorderingConsumer &) = delete;
264  ReorderingConsumer &operator=(const ReorderingConsumer &) = delete;
265 
266  void HandleTranslationUnit(ASTContext &Context) override {
267  const RecordDecl *RD = findDefinition(RecordName, Context);
268  if (!RD)
269  return;
270  SmallVector<unsigned, 4> NewFieldsOrder =
271  getNewFieldsOrder(RD, DesiredFieldsOrder);
272  if (NewFieldsOrder.empty())
273  return;
274  if (!reorderFieldsInDefinition(RD, NewFieldsOrder, Context, Replacements))
275  return;
276 
277  // CXXRD will be nullptr if C code (not C++) is being processed.
278  const CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(RD);
279  if (CXXRD)
280  for (const auto *C : CXXRD->ctors())
281  if (const auto *D = dyn_cast<CXXConstructorDecl>(C->getDefinition()))
282  reorderFieldsInConstructor(cast<const CXXConstructorDecl>(D),
283  NewFieldsOrder, Context, Replacements);
284 
285  // We only need to reorder init list expressions for
286  // plain C structs or C++ aggregate types.
287  // For other types the order of constructor parameters is used,
288  // which we don't change at the moment.
289  // Now (v0) partial initialization is not supported.
290  if (!CXXRD || CXXRD->isAggregate())
291  for (auto Result :
292  match(initListExpr(hasType(equalsNode(RD))).bind("initListExpr"),
293  Context))
295  Result.getNodeAs<InitListExpr>("initListExpr"), NewFieldsOrder,
296  Context, Replacements)) {
297  Replacements.clear();
298  return;
299  }
300  }
301 };
302 } // end anonymous namespace
303 
304 std::unique_ptr<ASTConsumer> ReorderFieldsAction::newASTConsumer() {
305  return std::make_unique<ReorderingConsumer>(RecordName, DesiredFieldsOrder,
306  Replacements);
307 }
308 
309 } // namespace reorder_fields
310 } // namespace clang
static cl::opt< std::string > RecordName("record-name", cl::Required, cl::desc("The name of the struct/class."), cl::cat(ClangReorderFieldsCategory))
static void addReplacement(SourceRange Old, SourceRange New, const ASTContext &Context, std::map< std::string, tooling::Replacements > &Replacements)
Replaces one range of source code by another.
static bool reorderFieldsInDefinition(const RecordDecl *Definition, ArrayRef< unsigned > NewFieldsOrder, const ASTContext &Context, std::map< std::string, tooling::Replacements > &Replacements)
Reorders fields in the definition of a struct/class.
static const RecordDecl * findDefinition(StringRef RecordName, ASTContext &Context)
Finds the definition of a record by name.
std::unique_ptr< ASTConsumer > newASTConsumer()
std::vector< CodeCompletionResult > Results
This file contains the declarations of the ReorderFieldsAction class and the FieldPosition struct...
static SmallVector< unsigned, 4 > getNewFieldsOrder(const RecordDecl *Definition, ArrayRef< std::string > DesiredFieldsOrder)
Calculates the new order of fields.
static SmallSetVector< FieldDecl *, 1 > findMembersUsedInInitExpr(const CXXCtorInitializer *Initializer, ASTContext &Context)
Find all member fields used in the given init-list initializer expr that belong to the same record...
std::vector< std::string > match(const SymbolIndex &I, const FuzzyFindRequest &Req, bool *Incomplete)
Definition: TestIndex.cpp:94
static constexpr llvm::StringLiteral Name
llvm::Optional< Range > getTokenRange(const SourceManager &SM, const LangOptions &LangOpts, SourceLocation TokLoc)
Returns the taken range at TokLoc.
Definition: SourceCode.cpp:227
static bool reorderFieldsInInitListExpr(const InitListExpr *InitListEx, ArrayRef< unsigned > NewFieldsOrder, const ASTContext &Context, std::map< std::string, tooling::Replacements > &Replacements)
Reorders initializers in the brace initialization of an aggregate.
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
const char * Description
Definition: Dexp.cpp:257
static void reorderFieldsInConstructor(const CXXConstructorDecl *CtorDecl, ArrayRef< unsigned > NewFieldsOrder, ASTContext &Context, std::map< std::string, tooling::Replacements > &Replacements)
Reorders initializers in a C++ struct/class constructor.