clang-tools  11.0.0
QualifiedAutoCheck.cpp
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1 //===--- QualifiedAutoCheck.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 "QualifiedAutoCheck.h"
10 #include "../utils/LexerUtils.h"
11 #include "clang/ASTMatchers/ASTMatchers.h"
12 #include "llvm/ADT/Optional.h"
13 #include "llvm/ADT/SmallVector.h"
14 
15 using namespace clang::ast_matchers;
16 
17 namespace clang {
18 namespace tidy {
19 namespace readability {
20 
21 namespace {
22 
23 // FIXME move to ASTMatchers
24 AST_MATCHER_P(QualType, hasUnqualifiedType,
25  ast_matchers::internal::Matcher<QualType>, InnerMatcher) {
26  return InnerMatcher.matches(Node.getUnqualifiedType(), Finder, Builder);
27 }
28 
29 enum class Qualifier { Const, Volatile, Restrict };
30 
31 llvm::Optional<Token> findQualToken(const VarDecl *Decl, Qualifier Qual,
32  const MatchFinder::MatchResult &Result) {
33  // Since either of the locs can be in a macro, use `makeFileCharRange` to be
34  // sure that we have a consistent `CharSourceRange`, located entirely in the
35  // source file.
36 
37  assert((Qual == Qualifier::Const || Qual == Qualifier::Volatile ||
38  Qual == Qualifier::Restrict) &&
39  "Invalid Qualifier");
40 
41  SourceLocation BeginLoc = Decl->getQualifierLoc().getBeginLoc();
42  if (BeginLoc.isInvalid())
43  BeginLoc = Decl->getBeginLoc();
44  SourceLocation EndLoc = Decl->getLocation();
45 
46  CharSourceRange FileRange = Lexer::makeFileCharRange(
47  CharSourceRange::getCharRange(BeginLoc, EndLoc), *Result.SourceManager,
48  Result.Context->getLangOpts());
49 
50  if (FileRange.isInvalid())
51  return llvm::None;
52 
53  tok::TokenKind Tok =
54  Qual == Qualifier::Const
55  ? tok::kw_const
56  : Qual == Qualifier::Volatile ? tok::kw_volatile : tok::kw_restrict;
57 
58  return utils::lexer::getQualifyingToken(Tok, FileRange, *Result.Context,
59  *Result.SourceManager);
60 }
61 
62 llvm::Optional<SourceRange>
63 getTypeSpecifierLocation(const VarDecl *Var,
64  const MatchFinder::MatchResult &Result) {
65  SourceRange TypeSpecifier(
66  Var->getTypeSpecStartLoc(),
67  Var->getTypeSpecEndLoc().getLocWithOffset(Lexer::MeasureTokenLength(
68  Var->getTypeSpecEndLoc(), *Result.SourceManager,
69  Result.Context->getLangOpts())));
70 
71  if (TypeSpecifier.getBegin().isMacroID() ||
72  TypeSpecifier.getEnd().isMacroID())
73  return llvm::None;
74  return TypeSpecifier;
75 }
76 
77 llvm::Optional<SourceRange> mergeReplacementRange(SourceRange &TypeSpecifier,
78  const Token &ConstToken) {
79  if (TypeSpecifier.getBegin().getLocWithOffset(-1) == ConstToken.getEndLoc()) {
80  TypeSpecifier.setBegin(ConstToken.getLocation());
81  return llvm::None;
82  }
83  if (TypeSpecifier.getEnd().getLocWithOffset(1) == ConstToken.getLocation()) {
84  TypeSpecifier.setEnd(ConstToken.getEndLoc());
85  return llvm::None;
86  }
87  return SourceRange(ConstToken.getLocation(), ConstToken.getEndLoc());
88 }
89 
90 bool isPointerConst(QualType QType) {
91  QualType Pointee = QType->getPointeeType();
92  assert(!Pointee.isNull() && "can't have a null Pointee");
93  return Pointee.isConstQualified();
94 }
95 
96 bool isAutoPointerConst(QualType QType) {
97  QualType Pointee =
98  cast<AutoType>(QType->getPointeeType().getTypePtr())->desugar();
99  assert(!Pointee.isNull() && "can't have a null Pointee");
100  return Pointee.isConstQualified();
101 }
102 
103 } // namespace
104 
105 void QualifiedAutoCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
106  Options.store(Opts, "AddConstToQualified", AddConstToQualified);
107 }
108 
109 void QualifiedAutoCheck::registerMatchers(MatchFinder *Finder) {
110  auto ExplicitSingleVarDecl =
111  [](const ast_matchers::internal::Matcher<VarDecl> &InnerMatcher,
112  llvm::StringRef ID) {
113  return declStmt(
114  unless(isInTemplateInstantiation()),
115  hasSingleDecl(
116  varDecl(unless(isImplicit()), InnerMatcher).bind(ID)));
117  };
118  auto ExplicitSingleVarDeclInTemplate =
119  [](const ast_matchers::internal::Matcher<VarDecl> &InnerMatcher,
120  llvm::StringRef ID) {
121  return declStmt(
122  isInTemplateInstantiation(),
123  hasSingleDecl(
124  varDecl(unless(isImplicit()), InnerMatcher).bind(ID)));
125  };
126 
127  auto IsBoundToType = refersToType(equalsBoundNode("type"));
128 
129  Finder->addMatcher(
130  ExplicitSingleVarDecl(hasType(autoType(hasDeducedType(
131  pointerType(pointee(unless(functionType())))))),
132  "auto"),
133  this);
134 
135  Finder->addMatcher(
136  ExplicitSingleVarDeclInTemplate(
137  allOf(hasType(autoType(hasDeducedType(pointerType(
138  pointee(hasUnqualifiedType(qualType().bind("type")),
139  unless(functionType())))))),
140  anyOf(hasAncestor(
141  functionDecl(hasAnyTemplateArgument(IsBoundToType))),
142  hasAncestor(classTemplateSpecializationDecl(
143  hasAnyTemplateArgument(IsBoundToType))))),
144  "auto"),
145  this);
146  if (!AddConstToQualified)
147  return;
148  Finder->addMatcher(ExplicitSingleVarDecl(
149  hasType(pointerType(pointee(autoType()))), "auto_ptr"),
150  this);
151  Finder->addMatcher(
152  ExplicitSingleVarDecl(hasType(lValueReferenceType(pointee(autoType()))),
153  "auto_ref"),
154  this);
155 }
156 
157 void QualifiedAutoCheck::check(const MatchFinder::MatchResult &Result) {
158  if (const auto *Var = Result.Nodes.getNodeAs<VarDecl>("auto")) {
159  SourceRange TypeSpecifier;
160  if (llvm::Optional<SourceRange> TypeSpec =
161  getTypeSpecifierLocation(Var, Result)) {
162  TypeSpecifier = *TypeSpec;
163  } else
164  return;
165 
166  llvm::SmallVector<SourceRange, 4> RemoveQualifiersRange;
167  auto CheckQualifier = [&](bool IsPresent, Qualifier Qual) {
168  if (IsPresent) {
169  llvm::Optional<Token> Token = findQualToken(Var, Qual, Result);
170  if (!Token || Token->getLocation().isMacroID())
171  return true; // Disregard this VarDecl.
172  if (llvm::Optional<SourceRange> Result =
173  mergeReplacementRange(TypeSpecifier, *Token))
174  RemoveQualifiersRange.push_back(*Result);
175  }
176  return false;
177  };
178 
179  bool IsLocalConst = Var->getType().isLocalConstQualified();
180  bool IsLocalVolatile = Var->getType().isLocalVolatileQualified();
181  bool IsLocalRestrict = Var->getType().isLocalRestrictQualified();
182 
183  if (CheckQualifier(IsLocalConst, Qualifier::Const) ||
184  CheckQualifier(IsLocalVolatile, Qualifier::Volatile) ||
185  CheckQualifier(IsLocalRestrict, Qualifier::Restrict))
186  return;
187 
188  // Check for bridging the gap between the asterisk and name.
189  if (Var->getLocation() == TypeSpecifier.getEnd().getLocWithOffset(1))
190  TypeSpecifier.setEnd(TypeSpecifier.getEnd().getLocWithOffset(1));
191 
192  CharSourceRange FixItRange = CharSourceRange::getCharRange(TypeSpecifier);
193  if (FixItRange.isInvalid())
194  return;
195 
196  SourceLocation FixitLoc = FixItRange.getBegin();
197  for (SourceRange &Range : RemoveQualifiersRange) {
198  if (Range.getBegin() < FixitLoc)
199  FixitLoc = Range.getBegin();
200  }
201 
202  std::string ReplStr = [&] {
203  llvm::StringRef PtrConst = isPointerConst(Var->getType()) ? "const " : "";
204  llvm::StringRef LocalConst = IsLocalConst ? "const " : "";
205  llvm::StringRef LocalVol = IsLocalVolatile ? "volatile " : "";
206  llvm::StringRef LocalRestrict = IsLocalRestrict ? "__restrict " : "";
207  return (PtrConst + "auto *" + LocalConst + LocalVol + LocalRestrict)
208  .str();
209  }();
210 
211  DiagnosticBuilder Diag =
212  diag(FixitLoc, "'%0%1%2auto %3' can be declared as '%4%3'")
213  << (IsLocalConst ? "const " : "")
214  << (IsLocalVolatile ? "volatile " : "")
215  << (IsLocalRestrict ? "__restrict " : "") << Var->getName() << ReplStr;
216 
217  for (SourceRange &Range : RemoveQualifiersRange) {
218  Diag << FixItHint::CreateRemoval(CharSourceRange::getCharRange(Range));
219  }
220 
221  Diag << FixItHint::CreateReplacement(FixItRange, ReplStr);
222  return;
223  }
224  if (const auto *Var = Result.Nodes.getNodeAs<VarDecl>("auto_ptr")) {
225  if (!isPointerConst(Var->getType()))
226  return; // Pointer isn't const, no need to add const qualifier.
227  if (!isAutoPointerConst(Var->getType()))
228  return; // Const isnt wrapped in the auto type, so must be declared
229  // explicitly.
230 
231  if (Var->getType().isLocalConstQualified()) {
232  llvm::Optional<Token> Token =
233  findQualToken(Var, Qualifier::Const, Result);
234  if (!Token || Token->getLocation().isMacroID())
235  return;
236  }
237  if (Var->getType().isLocalVolatileQualified()) {
238  llvm::Optional<Token> Token =
239  findQualToken(Var, Qualifier::Volatile, Result);
240  if (!Token || Token->getLocation().isMacroID())
241  return;
242  }
243  if (Var->getType().isLocalRestrictQualified()) {
244  llvm::Optional<Token> Token =
245  findQualToken(Var, Qualifier::Restrict, Result);
246  if (!Token || Token->getLocation().isMacroID())
247  return;
248  }
249 
250  if (llvm::Optional<SourceRange> TypeSpec =
251  getTypeSpecifierLocation(Var, Result)) {
252  if (TypeSpec->isInvalid() || TypeSpec->getBegin().isMacroID() ||
253  TypeSpec->getEnd().isMacroID())
254  return;
255  SourceLocation InsertPos = TypeSpec->getBegin();
256  diag(InsertPos, "'auto *%0%1%2' can be declared as 'const auto *%0%1%2'")
257  << (Var->getType().isLocalConstQualified() ? "const " : "")
258  << (Var->getType().isLocalVolatileQualified() ? "volatile " : "")
259  << Var->getName() << FixItHint::CreateInsertion(InsertPos, "const ");
260  }
261  return;
262  }
263  if (const auto *Var = Result.Nodes.getNodeAs<VarDecl>("auto_ref")) {
264  if (!isPointerConst(Var->getType()))
265  return; // Pointer isn't const, no need to add const qualifier.
266  if (!isAutoPointerConst(Var->getType()))
267  // Const isnt wrapped in the auto type, so must be declared explicitly.
268  return;
269 
270  if (llvm::Optional<SourceRange> TypeSpec =
271  getTypeSpecifierLocation(Var, Result)) {
272  if (TypeSpec->isInvalid() || TypeSpec->getBegin().isMacroID() ||
273  TypeSpec->getEnd().isMacroID())
274  return;
275  SourceLocation InsertPos = TypeSpec->getBegin();
276  diag(InsertPos, "'auto &%0' can be declared as 'const auto &%0'")
277  << Var->getName() << FixItHint::CreateInsertion(InsertPos, "const ");
278  }
279  return;
280  }
281 }
282 
283 } // namespace readability
284 } // namespace tidy
285 } // namespace clang
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