clang  8.0.0svn
DynamicTypeChecker.cpp
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1 //== DynamicTypeChecker.cpp ------------------------------------ -*- C++ -*--=//
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 //
10 // This checker looks for cases where the dynamic type of an object is unrelated
11 // to its static type. The type information utilized by this check is collected
12 // by the DynamicTypePropagation checker. This check does not report any type
13 // error for ObjC Generic types, in order to avoid duplicate erros from the
14 // ObjC Generics checker. This checker is not supposed to modify the program
15 // state, it is just the observer of the type information provided by other
16 // checkers.
17 //
18 //===----------------------------------------------------------------------===//
19 
20 #include "ClangSACheckers.h"
28 
29 using namespace clang;
30 using namespace ento;
31 
32 namespace {
33 class DynamicTypeChecker : public Checker<check::PostStmt<ImplicitCastExpr>> {
34  mutable std::unique_ptr<BugType> BT;
35  void initBugType() const {
36  if (!BT)
37  BT.reset(
38  new BugType(this, "Dynamic and static type mismatch", "Type Error"));
39  }
40 
41  class DynamicTypeBugVisitor : public BugReporterVisitor {
42  public:
43  DynamicTypeBugVisitor(const MemRegion *Reg) : Reg(Reg) {}
44 
45  void Profile(llvm::FoldingSetNodeID &ID) const override {
46  static int X = 0;
47  ID.AddPointer(&X);
48  ID.AddPointer(Reg);
49  }
50 
51  std::shared_ptr<PathDiagnosticPiece> VisitNode(const ExplodedNode *N,
52  BugReporterContext &BRC,
53  BugReport &BR) override;
54 
55  private:
56  // The tracked region.
57  const MemRegion *Reg;
58  };
59 
60  void reportTypeError(QualType DynamicType, QualType StaticType,
61  const MemRegion *Reg, const Stmt *ReportedNode,
62  CheckerContext &C) const;
63 
64 public:
65  void checkPostStmt(const ImplicitCastExpr *CE, CheckerContext &C) const;
66 };
67 }
68 
69 void DynamicTypeChecker::reportTypeError(QualType DynamicType,
70  QualType StaticType,
71  const MemRegion *Reg,
72  const Stmt *ReportedNode,
73  CheckerContext &C) const {
74  initBugType();
75  SmallString<192> Buf;
76  llvm::raw_svector_ostream OS(Buf);
77  OS << "Object has a dynamic type '";
78  QualType::print(DynamicType.getTypePtr(), Qualifiers(), OS, C.getLangOpts(),
79  llvm::Twine());
80  OS << "' which is incompatible with static type '";
81  QualType::print(StaticType.getTypePtr(), Qualifiers(), OS, C.getLangOpts(),
82  llvm::Twine());
83  OS << "'";
84  std::unique_ptr<BugReport> R(
85  new BugReport(*BT, OS.str(), C.generateNonFatalErrorNode()));
86  R->markInteresting(Reg);
87  R->addVisitor(llvm::make_unique<DynamicTypeBugVisitor>(Reg));
88  R->addRange(ReportedNode->getSourceRange());
89  C.emitReport(std::move(R));
90 }
91 
92 std::shared_ptr<PathDiagnosticPiece>
93 DynamicTypeChecker::DynamicTypeBugVisitor::VisitNode(const ExplodedNode *N,
94  BugReporterContext &BRC,
95  BugReport &) {
96  ProgramStateRef State = N->getState();
97  ProgramStateRef StatePrev = N->getFirstPred()->getState();
98 
99  DynamicTypeInfo TrackedType = getDynamicTypeInfo(State, Reg);
100  DynamicTypeInfo TrackedTypePrev = getDynamicTypeInfo(StatePrev, Reg);
101  if (!TrackedType.isValid())
102  return nullptr;
103 
104  if (TrackedTypePrev.isValid() &&
105  TrackedTypePrev.getType() == TrackedType.getType())
106  return nullptr;
107 
108  // Retrieve the associated statement.
110  if (!S)
111  return nullptr;
112 
113  const LangOptions &LangOpts = BRC.getASTContext().getLangOpts();
114 
115  SmallString<256> Buf;
116  llvm::raw_svector_ostream OS(Buf);
117  OS << "Type '";
118  QualType::print(TrackedType.getType().getTypePtr(), Qualifiers(), OS,
119  LangOpts, llvm::Twine());
120  OS << "' is inferred from ";
121 
122  if (const auto *ExplicitCast = dyn_cast<ExplicitCastExpr>(S)) {
123  OS << "explicit cast (from '";
124  QualType::print(ExplicitCast->getSubExpr()->getType().getTypePtr(),
125  Qualifiers(), OS, LangOpts, llvm::Twine());
126  OS << "' to '";
127  QualType::print(ExplicitCast->getType().getTypePtr(), Qualifiers(), OS,
128  LangOpts, llvm::Twine());
129  OS << "')";
130  } else if (const auto *ImplicitCast = dyn_cast<ImplicitCastExpr>(S)) {
131  OS << "implicit cast (from '";
132  QualType::print(ImplicitCast->getSubExpr()->getType().getTypePtr(),
133  Qualifiers(), OS, LangOpts, llvm::Twine());
134  OS << "' to '";
135  QualType::print(ImplicitCast->getType().getTypePtr(), Qualifiers(), OS,
136  LangOpts, llvm::Twine());
137  OS << "')";
138  } else {
139  OS << "this context";
140  }
141 
142  // Generate the extra diagnostic.
143  PathDiagnosticLocation Pos(S, BRC.getSourceManager(),
144  N->getLocationContext());
145  return std::make_shared<PathDiagnosticEventPiece>(Pos, OS.str(), true,
146  nullptr);
147 }
148 
149 static bool hasDefinition(const ObjCObjectPointerType *ObjPtr) {
150  const ObjCInterfaceDecl *Decl = ObjPtr->getInterfaceDecl();
151  if (!Decl)
152  return false;
153 
154  return Decl->getDefinition();
155 }
156 
157 // TODO: consider checking explicit casts?
158 void DynamicTypeChecker::checkPostStmt(const ImplicitCastExpr *CE,
159  CheckerContext &C) const {
160  // TODO: C++ support.
161  if (CE->getCastKind() != CK_BitCast)
162  return;
163 
164  const MemRegion *Region = C.getSVal(CE).getAsRegion();
165  if (!Region)
166  return;
167 
168  ProgramStateRef State = C.getState();
169  DynamicTypeInfo DynTypeInfo = getDynamicTypeInfo(State, Region);
170 
171  if (!DynTypeInfo.isValid())
172  return;
173 
174  QualType DynType = DynTypeInfo.getType();
175  QualType StaticType = CE->getType();
176 
177  const auto *DynObjCType = DynType->getAs<ObjCObjectPointerType>();
178  const auto *StaticObjCType = StaticType->getAs<ObjCObjectPointerType>();
179 
180  if (!DynObjCType || !StaticObjCType)
181  return;
182 
183  if (!hasDefinition(DynObjCType) || !hasDefinition(StaticObjCType))
184  return;
185 
186  ASTContext &ASTCtxt = C.getASTContext();
187 
188  // Strip kindeofness to correctly detect subtyping relationships.
189  DynObjCType = DynObjCType->stripObjCKindOfTypeAndQuals(ASTCtxt);
190  StaticObjCType = StaticObjCType->stripObjCKindOfTypeAndQuals(ASTCtxt);
191 
192  // Specialized objects are handled by the generics checker.
193  if (StaticObjCType->isSpecialized())
194  return;
195 
196  if (ASTCtxt.canAssignObjCInterfaces(StaticObjCType, DynObjCType))
197  return;
198 
199  if (DynTypeInfo.canBeASubClass() &&
200  ASTCtxt.canAssignObjCInterfaces(DynObjCType, StaticObjCType))
201  return;
202 
203  reportTypeError(DynType, StaticType, Region, CE, C);
204 }
205 
206 void ento::registerDynamicTypeChecker(CheckerManager &mgr) {
207  mgr.registerChecker<DynamicTypeChecker>();
208 }
A (possibly-)qualified type.
Definition: Type.h:642
void print(raw_ostream &OS, const PrintingPolicy &Policy, const Twine &PlaceHolder=Twine(), unsigned Indentation=0) const
Definition: Type.h:985
Stmt - This represents one statement.
Definition: Stmt.h:66
Decl - This represents one declaration (or definition), e.g.
Definition: DeclBase.h:87
IntrusiveRefCntPtr< const ProgramState > ProgramStateRef
const T * getAs() const
Member-template getAs<specific type>&#39;.
Definition: Type.h:6716
The collection of all-type qualifiers we support.
Definition: Type.h:141
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:154
LineState State
bool isSpecialized() const
Whether this type is specialized, meaning that it has type arguments.
Definition: Type.h:5873
Keeps track of the various options that can be enabled, which controls the dialect of C or C++ that i...
Definition: LangOptions.h:50
const ObjCObjectPointerType * stripObjCKindOfTypeAndQuals(const ASTContext &ctx) const
Strip off the Objective-C "kindof" type and (with it) any protocol qualifiers.
Definition: Type.cpp:709
const Type * getTypePtr() const
Retrieves a pointer to the underlying (unqualified) type.
Definition: Type.h:6058
Represents an ObjC class declaration.
Definition: DeclObjC.h:1164
QualType getType() const
Definition: Expr.h:128
static bool hasDefinition(const ObjCObjectPointerType *ObjPtr)
static const Stmt * getStmt(const ExplodedNode *N)
Given an exploded node, retrieve the statement that should be used for the diagnostic location...
CastKind getCastKind() const
Definition: Expr.h:2962
ImplicitCastExpr - Allows us to explicitly represent implicit type conversions, which have no direct ...
Definition: Expr.h:3037
Dataflow Directional Tag Classes.
DynamicTypeInfo getDynamicTypeInfo(ProgramStateRef State, const MemRegion *Reg)
Get dynamic type information for a region.
ObjCInterfaceDecl * getDefinition()
Retrieve the definition of this class, or NULL if this class has been forward-declared (with @class) ...
Definition: DeclObjC.h:1541
Represents a pointer to an Objective C object.
Definition: Type.h:5780
ObjCInterfaceDecl * getInterfaceDecl() const
If this pointer points to an Objective @interface type, gets the declaration for that interface...
Definition: Type.h:5836
bool canAssignObjCInterfaces(const ObjCObjectPointerType *LHSOPT, const ObjCObjectPointerType *RHSOPT)
canAssignObjCInterfaces - Return true if the two interface types are compatible for assignment from R...
X
Add a minimal nested name specifier fixit hint to allow lookup of a tag name from an outer enclosing ...
Definition: SemaDecl.cpp:13853
SourceRange getSourceRange() const LLVM_READONLY
SourceLocation tokens are not useful in isolation - they are low level value objects created/interpre...
Definition: Stmt.cpp:268