clang-tools  10.0.0git
ImplicitBoolConversionCheck.cpp
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1 //===--- ImplicitBoolConversionCheck.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 #include "clang/Lex/Lexer.h"
13 #include "clang/Tooling/FixIt.h"
14 #include <queue>
15 
16 using namespace clang::ast_matchers;
17 
18 namespace clang {
19 namespace tidy {
20 namespace readability {
21 
22 namespace {
23 
24 AST_MATCHER(Stmt, isMacroExpansion) {
25  SourceManager &SM = Finder->getASTContext().getSourceManager();
26  SourceLocation Loc = Node.getBeginLoc();
27  return SM.isMacroBodyExpansion(Loc) || SM.isMacroArgExpansion(Loc);
28 }
29 
30 bool isNULLMacroExpansion(const Stmt *Statement, ASTContext &Context) {
31  SourceManager &SM = Context.getSourceManager();
32  const LangOptions &LO = Context.getLangOpts();
33  SourceLocation Loc = Statement->getBeginLoc();
34  return SM.isMacroBodyExpansion(Loc) &&
35  Lexer::getImmediateMacroName(Loc, SM, LO) == "NULL";
36 }
37 
38 AST_MATCHER(Stmt, isNULLMacroExpansion) {
39  return isNULLMacroExpansion(&Node, Finder->getASTContext());
40 }
41 
42 StringRef getZeroLiteralToCompareWithForType(CastKind CastExprKind,
43  QualType Type,
44  ASTContext &Context) {
45  switch (CastExprKind) {
46  case CK_IntegralToBoolean:
47  return Type->isUnsignedIntegerType() ? "0u" : "0";
48 
49  case CK_FloatingToBoolean:
50  return Context.hasSameType(Type, Context.FloatTy) ? "0.0f" : "0.0";
51 
52  case CK_PointerToBoolean:
53  case CK_MemberPointerToBoolean: // Fall-through on purpose.
54  return Context.getLangOpts().CPlusPlus11 ? "nullptr" : "0";
55 
56  default:
57  llvm_unreachable("Unexpected cast kind");
58  }
59 }
60 
61 bool isUnaryLogicalNotOperator(const Stmt *Statement) {
62  const auto *UnaryOperatorExpr = dyn_cast<UnaryOperator>(Statement);
63  return UnaryOperatorExpr && UnaryOperatorExpr->getOpcode() == UO_LNot;
64 }
65 
66 bool areParensNeededForOverloadedOperator(OverloadedOperatorKind OperatorKind) {
67  switch (OperatorKind) {
68  case OO_New:
69  case OO_Delete: // Fall-through on purpose.
70  case OO_Array_New:
71  case OO_Array_Delete:
72  case OO_ArrowStar:
73  case OO_Arrow:
74  case OO_Call:
75  case OO_Subscript:
76  return false;
77 
78  default:
79  return true;
80  }
81 }
82 
83 bool areParensNeededForStatement(const Stmt *Statement) {
84  if (const auto *OperatorCall = dyn_cast<CXXOperatorCallExpr>(Statement)) {
85  return areParensNeededForOverloadedOperator(OperatorCall->getOperator());
86  }
87 
88  return isa<BinaryOperator>(Statement) || isa<UnaryOperator>(Statement);
89 }
90 
91 void fixGenericExprCastToBool(DiagnosticBuilder &Diag,
92  const ImplicitCastExpr *Cast, const Stmt *Parent,
93  ASTContext &Context) {
94  // In case of expressions like (! integer), we should remove the redundant not
95  // operator and use inverted comparison (integer == 0).
96  bool InvertComparison =
97  Parent != nullptr && isUnaryLogicalNotOperator(Parent);
98  if (InvertComparison) {
99  SourceLocation ParentStartLoc = Parent->getBeginLoc();
100  SourceLocation ParentEndLoc =
101  cast<UnaryOperator>(Parent)->getSubExpr()->getBeginLoc();
102  Diag << FixItHint::CreateRemoval(
103  CharSourceRange::getCharRange(ParentStartLoc, ParentEndLoc));
104 
105  Parent = Context.getParents(*Parent)[0].get<Stmt>();
106  }
107 
108  const Expr *SubExpr = Cast->getSubExpr();
109 
110  bool NeedInnerParens = areParensNeededForStatement(SubExpr);
111  bool NeedOuterParens =
112  Parent != nullptr && areParensNeededForStatement(Parent);
113 
114  std::string StartLocInsertion;
115 
116  if (NeedOuterParens) {
117  StartLocInsertion += "(";
118  }
119  if (NeedInnerParens) {
120  StartLocInsertion += "(";
121  }
122 
123  if (!StartLocInsertion.empty()) {
124  Diag << FixItHint::CreateInsertion(Cast->getBeginLoc(), StartLocInsertion);
125  }
126 
127  std::string EndLocInsertion;
128 
129  if (NeedInnerParens) {
130  EndLocInsertion += ")";
131  }
132 
133  if (InvertComparison) {
134  EndLocInsertion += " == ";
135  } else {
136  EndLocInsertion += " != ";
137  }
138 
139  EndLocInsertion += getZeroLiteralToCompareWithForType(
140  Cast->getCastKind(), SubExpr->getType(), Context);
141 
142  if (NeedOuterParens) {
143  EndLocInsertion += ")";
144  }
145 
146  SourceLocation EndLoc = Lexer::getLocForEndOfToken(
147  Cast->getEndLoc(), 0, Context.getSourceManager(), Context.getLangOpts());
148  Diag << FixItHint::CreateInsertion(EndLoc, EndLocInsertion);
149 }
150 
151 StringRef getEquivalentBoolLiteralForExpr(const Expr *Expression,
152  ASTContext &Context) {
153  if (isNULLMacroExpansion(Expression, Context)) {
154  return "false";
155  }
156 
157  if (const auto *IntLit = dyn_cast<IntegerLiteral>(Expression)) {
158  return (IntLit->getValue() == 0) ? "false" : "true";
159  }
160 
161  if (const auto *FloatLit = dyn_cast<FloatingLiteral>(Expression)) {
162  llvm::APFloat FloatLitAbsValue = FloatLit->getValue();
163  FloatLitAbsValue.clearSign();
164  return (FloatLitAbsValue.bitcastToAPInt() == 0) ? "false" : "true";
165  }
166 
167  if (const auto *CharLit = dyn_cast<CharacterLiteral>(Expression)) {
168  return (CharLit->getValue() == 0) ? "false" : "true";
169  }
170 
171  if (isa<StringLiteral>(Expression->IgnoreCasts())) {
172  return "true";
173  }
174 
175  return StringRef();
176 }
177 
178 void fixGenericExprCastFromBool(DiagnosticBuilder &Diag,
179  const ImplicitCastExpr *Cast,
180  ASTContext &Context, StringRef OtherType) {
181  const Expr *SubExpr = Cast->getSubExpr();
182  bool NeedParens = !isa<ParenExpr>(SubExpr);
183 
184  Diag << FixItHint::CreateInsertion(
185  Cast->getBeginLoc(),
186  (Twine("static_cast<") + OtherType + ">" + (NeedParens ? "(" : ""))
187  .str());
188 
189  if (NeedParens) {
190  SourceLocation EndLoc = Lexer::getLocForEndOfToken(
191  Cast->getEndLoc(), 0, Context.getSourceManager(),
192  Context.getLangOpts());
193 
194  Diag << FixItHint::CreateInsertion(EndLoc, ")");
195  }
196 }
197 
198 StringRef getEquivalentForBoolLiteral(const CXXBoolLiteralExpr *BoolLiteral,
199  QualType DestType, ASTContext &Context) {
200  // Prior to C++11, false literal could be implicitly converted to pointer.
201  if (!Context.getLangOpts().CPlusPlus11 &&
202  (DestType->isPointerType() || DestType->isMemberPointerType()) &&
203  BoolLiteral->getValue() == false) {
204  return "0";
205  }
206 
207  if (DestType->isFloatingType()) {
208  if (Context.hasSameType(DestType, Context.FloatTy)) {
209  return BoolLiteral->getValue() ? "1.0f" : "0.0f";
210  }
211  return BoolLiteral->getValue() ? "1.0" : "0.0";
212  }
213 
214  if (DestType->isUnsignedIntegerType()) {
215  return BoolLiteral->getValue() ? "1u" : "0u";
216  }
217  return BoolLiteral->getValue() ? "1" : "0";
218 }
219 
220 bool isCastAllowedInCondition(const ImplicitCastExpr *Cast,
221  ASTContext &Context) {
222  std::queue<const Stmt *> Q;
223  Q.push(Cast);
224  while (!Q.empty()) {
225  for (const auto &N : Context.getParents(*Q.front())) {
226  const Stmt *S = N.get<Stmt>();
227  if (!S)
228  return false;
229  if (isa<IfStmt>(S) || isa<ConditionalOperator>(S) || isa<ForStmt>(S) ||
230  isa<WhileStmt>(S) || isa<BinaryConditionalOperator>(S))
231  return true;
232  if (isa<ParenExpr>(S) || isa<ImplicitCastExpr>(S) ||
233  isUnaryLogicalNotOperator(S) ||
234  (isa<BinaryOperator>(S) && cast<BinaryOperator>(S)->isLogicalOp())) {
235  Q.push(S);
236  } else {
237  return false;
238  }
239  }
240  Q.pop();
241  }
242  return false;
243 }
244 
245 } // anonymous namespace
246 
247 ImplicitBoolConversionCheck::ImplicitBoolConversionCheck(
248  StringRef Name, ClangTidyContext *Context)
249  : ClangTidyCheck(Name, Context),
250  AllowIntegerConditions(Options.get("AllowIntegerConditions", false)),
251  AllowPointerConditions(Options.get("AllowPointerConditions", false)) {}
252 
255  Options.store(Opts, "AllowIntegerConditions", AllowIntegerConditions);
256  Options.store(Opts, "AllowPointerConditions", AllowPointerConditions);
257 }
258 
260  // This check doesn't make much sense if we run it on language without
261  // built-in bool support.
262  if (!getLangOpts().Bool) {
263  return;
264  }
265 
266  auto exceptionCases =
267  expr(anyOf(allOf(isMacroExpansion(), unless(isNULLMacroExpansion())),
268  has(ignoringImplicit(memberExpr(hasDeclaration(fieldDecl(hasBitWidth(1)))))),
269  hasParent(explicitCastExpr())));
270  auto implicitCastFromBool = implicitCastExpr(
271  anyOf(hasCastKind(CK_IntegralCast), hasCastKind(CK_IntegralToFloating),
272  // Prior to C++11 cast from bool literal to pointer was allowed.
273  allOf(anyOf(hasCastKind(CK_NullToPointer),
274  hasCastKind(CK_NullToMemberPointer)),
275  hasSourceExpression(cxxBoolLiteral()))),
276  hasSourceExpression(expr(hasType(booleanType()))),
277  unless(exceptionCases));
278  auto boolXor =
279  binaryOperator(hasOperatorName("^"), hasLHS(implicitCastFromBool),
280  hasRHS(implicitCastFromBool));
281  Finder->addMatcher(
282  implicitCastExpr(
283  anyOf(hasCastKind(CK_IntegralToBoolean),
284  hasCastKind(CK_FloatingToBoolean),
285  hasCastKind(CK_PointerToBoolean),
286  hasCastKind(CK_MemberPointerToBoolean)),
287  // Exclude case of using if or while statements with variable
288  // declaration, e.g.:
289  // if (int var = functionCall()) {}
290  unless(
291  hasParent(stmt(anyOf(ifStmt(), whileStmt()), has(declStmt())))),
292  // Exclude cases common to implicit cast to and from bool.
293  unless(exceptionCases), unless(has(boolXor)),
294  // Retrive also parent statement, to check if we need additional
295  // parens in replacement.
296  anyOf(hasParent(stmt().bind("parentStmt")), anything()),
297  unless(isInTemplateInstantiation()),
298  unless(hasAncestor(functionTemplateDecl())))
299  .bind("implicitCastToBool"),
300  this);
301 
302  auto boolComparison = binaryOperator(
303  anyOf(hasOperatorName("=="), hasOperatorName("!=")),
304  hasLHS(implicitCastFromBool), hasRHS(implicitCastFromBool));
305  auto boolOpAssignment =
306  binaryOperator(anyOf(hasOperatorName("|="), hasOperatorName("&=")),
307  hasLHS(expr(hasType(booleanType()))));
308  auto bitfieldAssignment = binaryOperator(
309  hasLHS(memberExpr(hasDeclaration(fieldDecl(hasBitWidth(1))))));
310  auto bitfieldConstruct = cxxConstructorDecl(hasDescendant(cxxCtorInitializer(
311  withInitializer(equalsBoundNode("implicitCastFromBool")),
312  forField(hasBitWidth(1)))));
313  Finder->addMatcher(
314  implicitCastExpr(
315  implicitCastFromBool,
316  // Exclude comparisons of bools, as they are always cast to integers
317  // in such context:
318  // bool_expr_a == bool_expr_b
319  // bool_expr_a != bool_expr_b
320  unless(hasParent(binaryOperator(anyOf(
321  boolComparison, boolXor, boolOpAssignment, bitfieldAssignment)))),
322  implicitCastExpr().bind("implicitCastFromBool"),
323  unless(hasParent(bitfieldConstruct)),
324  // Check also for nested casts, for example: bool -> int -> float.
325  anyOf(hasParent(implicitCastExpr().bind("furtherImplicitCast")),
326  anything()),
327  unless(isInTemplateInstantiation()),
328  unless(hasAncestor(functionTemplateDecl()))),
329  this);
330 }
331 
333  const MatchFinder::MatchResult &Result) {
334  if (const auto *CastToBool =
335  Result.Nodes.getNodeAs<ImplicitCastExpr>("implicitCastToBool")) {
336  const auto *Parent = Result.Nodes.getNodeAs<Stmt>("parentStmt");
337  return handleCastToBool(CastToBool, Parent, *Result.Context);
338  }
339 
340  if (const auto *CastFromBool =
341  Result.Nodes.getNodeAs<ImplicitCastExpr>("implicitCastFromBool")) {
342  const auto *NextImplicitCast =
343  Result.Nodes.getNodeAs<ImplicitCastExpr>("furtherImplicitCast");
344  return handleCastFromBool(CastFromBool, NextImplicitCast, *Result.Context);
345  }
346 }
347 
348 void ImplicitBoolConversionCheck::handleCastToBool(const ImplicitCastExpr *Cast,
349  const Stmt *Parent,
350  ASTContext &Context) {
351  if (AllowPointerConditions &&
352  (Cast->getCastKind() == CK_PointerToBoolean ||
353  Cast->getCastKind() == CK_MemberPointerToBoolean) &&
354  isCastAllowedInCondition(Cast, Context)) {
355  return;
356  }
357 
358  if (AllowIntegerConditions && Cast->getCastKind() == CK_IntegralToBoolean &&
359  isCastAllowedInCondition(Cast, Context)) {
360  return;
361  }
362 
363  auto Diag = diag(Cast->getBeginLoc(), "implicit conversion %0 -> bool")
364  << Cast->getSubExpr()->getType();
365 
366  StringRef EquivalentLiteral =
367  getEquivalentBoolLiteralForExpr(Cast->getSubExpr(), Context);
368  if (!EquivalentLiteral.empty()) {
369  Diag << tooling::fixit::createReplacement(*Cast, EquivalentLiteral);
370  } else {
371  fixGenericExprCastToBool(Diag, Cast, Parent, Context);
372  }
373 }
374 
375 void ImplicitBoolConversionCheck::handleCastFromBool(
376  const ImplicitCastExpr *Cast, const ImplicitCastExpr *NextImplicitCast,
377  ASTContext &Context) {
378  QualType DestType =
379  NextImplicitCast ? NextImplicitCast->getType() : Cast->getType();
380  auto Diag = diag(Cast->getBeginLoc(), "implicit conversion bool -> %0")
381  << DestType;
382 
383  if (const auto *BoolLiteral =
384  dyn_cast<CXXBoolLiteralExpr>(Cast->getSubExpr())) {
385  Diag << tooling::fixit::createReplacement(
386  *Cast, getEquivalentForBoolLiteral(BoolLiteral, DestType, Context));
387  } else {
388  fixGenericExprCastFromBool(Diag, Cast, Context, DestType.getAsString());
389  }
390 }
391 
392 } // namespace readability
393 } // namespace tidy
394 } // namespace clang
SourceLocation Loc
&#39;#&#39; location in the include directive
const Node * Parent
void registerMatchers(ast_matchers::MatchFinder *Finder) override
Override this to register AST matchers with Finder.
Base class for all clang-tidy checks.
const LangOptions & getLangOpts() const
Returns the language options from the context.
void check(const ast_matchers::MatchFinder::MatchResult &Result) override
ClangTidyChecks that register ASTMatchers should do the actual work in here.
void store(ClangTidyOptions::OptionMap &Options, StringRef LocalName, StringRef Value) const
Stores an option with the check-local name LocalName with string value Value to Options.
static constexpr llvm::StringLiteral Name
std::map< std::string, std::string > OptionMap
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//
Every ClangTidyCheck reports errors through a DiagnosticsEngine provided by this context.
void storeOptions(ClangTidyOptions::OptionMap &Opts) override
Should store all options supported by this check with their current values or default values for opti...
NodeType Type
DiagnosticBuilder diag(SourceLocation Loc, StringRef Description, DiagnosticIDs::Level Level=DiagnosticIDs::Warning)
Add a diagnostic with the check&#39;s name.