clang-tools  3.8.0
BoolPointerImplicitConversionCheck.cpp
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1 //===--- BoolPointerImplicitConversionCheck.cpp - clang-tidy --------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
11 
12 using namespace clang::ast_matchers;
13 
14 namespace clang {
15 namespace {
16 
17 AST_MATCHER(CastExpr, isPointerToBoolean) {
18  return Node.getCastKind() == CK_PointerToBoolean;
19 }
20 AST_MATCHER(QualType, isBoolean) { return Node->isBooleanType(); }
21 
22 } // namespace
23 
24 namespace tidy {
25 namespace misc {
26 
27 void BoolPointerImplicitConversionCheck::registerMatchers(MatchFinder *Finder) {
28  // Look for ifs that have an implicit bool* to bool conversion in the
29  // condition. Filter negations.
30  Finder->addMatcher(
31  ifStmt(hasCondition(findAll(implicitCastExpr(
32  allOf(unless(hasParent(unaryOperator(hasOperatorName("!")))),
33  hasSourceExpression(expr(
34  hasType(pointerType(pointee(isBoolean()))),
35  ignoringParenImpCasts(declRefExpr().bind("expr")))),
36  isPointerToBoolean())))),
37  unless(isInTemplateInstantiation())).bind("if"),
38  this);
39 }
40 
41 void BoolPointerImplicitConversionCheck::check(
42  const MatchFinder::MatchResult &Result) {
43  auto *If = Result.Nodes.getStmtAs<IfStmt>("if");
44  auto *Var = Result.Nodes.getStmtAs<DeclRefExpr>("expr");
45 
46  // Ignore macros.
47  if (Var->getLocStart().isMacroID())
48  return;
49 
50  // Only allow variable accesses for now, no function calls or member exprs.
51  // Check that we don't dereference the variable anywhere within the if. This
52  // avoids false positives for checks of the pointer for nullptr before it is
53  // dereferenced. If there is a dereferencing operator on this variable don't
54  // emit a diagnostic. Also ignore array subscripts.
55  const Decl *D = Var->getDecl();
56  auto DeclRef = ignoringParenImpCasts(declRefExpr(to(equalsNode(D))));
57  if (!match(findAll(
58  unaryOperator(hasOperatorName("*"), hasUnaryOperand(DeclRef))),
59  *If, *Result.Context).empty() ||
60  !match(findAll(arraySubscriptExpr(hasBase(DeclRef))), *If,
61  *Result.Context).empty() ||
62  // FIXME: We should still warn if the paremater is implicitly converted to
63  // bool.
64  !match(findAll(callExpr(hasAnyArgument(DeclRef))), *If, *Result.Context)
65  .empty() ||
66  !match(findAll(cxxDeleteExpr(has(expr(DeclRef)))), *If, *Result.Context)
67  .empty())
68  return;
69 
70  diag(Var->getLocStart(), "dubious check of 'bool *' against 'nullptr', did "
71  "you mean to dereference it?")
72  << FixItHint::CreateInsertion(Var->getLocStart(), "*");
73 }
74 
75 } // namespace misc
76 } // namespace tidy
77 } // namespace clang
std::unique_ptr< ast_matchers::MatchFinder > Finder
Definition: ClangTidy.cpp:188
AST_MATCHER(Stmt, isInsideOfRangeBeginEndStmt)
const NamedDecl * Result
Definition: USRFinder.cpp:121