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//== DynamicTypeChecker.cpp ------------------------------------ -*- C++ -*--=//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This checker looks for cases where the dynamic type of an object is unrelated
// to its static type. The type information utilized by this check is collected
// by the DynamicTypePropagation checker. This check does not report any type
// error for ObjC Generic types, in order to avoid duplicate erros from the
// ObjC Generics checker. This checker is not supposed to modify the program
// state, it is just the observer of the type information provided by other
// checkers.
//
//===----------------------------------------------------------------------===//
#include "ClangSACheckers.h"
#include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
#include "clang/StaticAnalyzer/Core/Checker.h"
#include "clang/StaticAnalyzer/Core/CheckerManager.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/DynamicTypeMap.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
using namespace clang;
using namespace ento;
namespace {
class DynamicTypeChecker : public Checker<check::PostStmt<ImplicitCastExpr>> {
mutable std::unique_ptr<BugType> BT;
void initBugType() const {
if (!BT)
BT.reset(
new BugType(this, "Dynamic and static type mismatch", "Type Error"));
}
class DynamicTypeBugVisitor
: public BugReporterVisitorImpl<DynamicTypeBugVisitor> {
public:
DynamicTypeBugVisitor(const MemRegion *Reg) : Reg(Reg) {}
void Profile(llvm::FoldingSetNodeID &ID) const override {
static int X = 0;
ID.AddPointer(&X);
ID.AddPointer(Reg);
}
PathDiagnosticPiece *VisitNode(const ExplodedNode *N,
const ExplodedNode *PrevN,
BugReporterContext &BRC,
BugReport &BR) override;
private:
// The tracked region.
const MemRegion *Reg;
};
void reportTypeError(QualType DynamicType, QualType StaticType,
const MemRegion *Reg, const Stmt *ReportedNode,
CheckerContext &C) const;
public:
void checkPostStmt(const ImplicitCastExpr *CE, CheckerContext &C) const;
};
}
void DynamicTypeChecker::reportTypeError(QualType DynamicType,
QualType StaticType,
const MemRegion *Reg,
const Stmt *ReportedNode,
CheckerContext &C) const {
initBugType();
SmallString<192> Buf;
llvm::raw_svector_ostream OS(Buf);
OS << "Object has a dynamic type '";
QualType::print(DynamicType.getTypePtr(), Qualifiers(), OS, C.getLangOpts(),
llvm::Twine());
OS << "' which is incompatible with static type '";
QualType::print(StaticType.getTypePtr(), Qualifiers(), OS, C.getLangOpts(),
llvm::Twine());
OS << "'";
std::unique_ptr<BugReport> R(
new BugReport(*BT, OS.str(), C.generateNonFatalErrorNode()));
R->markInteresting(Reg);
R->addVisitor(llvm::make_unique<DynamicTypeBugVisitor>(Reg));
R->addRange(ReportedNode->getSourceRange());
C.emitReport(std::move(R));
}
PathDiagnosticPiece *DynamicTypeChecker::DynamicTypeBugVisitor::VisitNode(
const ExplodedNode *N, const ExplodedNode *PrevN, BugReporterContext &BRC,
BugReport &BR) {
ProgramStateRef State = N->getState();
ProgramStateRef StatePrev = PrevN->getState();
DynamicTypeInfo TrackedType = getDynamicTypeInfo(State, Reg);
DynamicTypeInfo TrackedTypePrev = getDynamicTypeInfo(StatePrev, Reg);
if (!TrackedType.isValid())
return nullptr;
if (TrackedTypePrev.isValid() &&
TrackedTypePrev.getType() == TrackedType.getType())
return nullptr;
// Retrieve the associated statement.
const Stmt *S = PathDiagnosticLocation::getStmt(N);
if (!S)
return nullptr;
const LangOptions &LangOpts = BRC.getASTContext().getLangOpts();
SmallString<256> Buf;
llvm::raw_svector_ostream OS(Buf);
OS << "Type '";
QualType::print(TrackedType.getType().getTypePtr(), Qualifiers(), OS,
LangOpts, llvm::Twine());
OS << "' is inferred from ";
if (const auto *ExplicitCast = dyn_cast<ExplicitCastExpr>(S)) {
OS << "explicit cast (from '";
QualType::print(ExplicitCast->getSubExpr()->getType().getTypePtr(),
Qualifiers(), OS, LangOpts, llvm::Twine());
OS << "' to '";
QualType::print(ExplicitCast->getType().getTypePtr(), Qualifiers(), OS,
LangOpts, llvm::Twine());
OS << "')";
} else if (const auto *ImplicitCast = dyn_cast<ImplicitCastExpr>(S)) {
OS << "implicit cast (from '";
QualType::print(ImplicitCast->getSubExpr()->getType().getTypePtr(),
Qualifiers(), OS, LangOpts, llvm::Twine());
OS << "' to '";
QualType::print(ImplicitCast->getType().getTypePtr(), Qualifiers(), OS,
LangOpts, llvm::Twine());
OS << "')";
} else {
OS << "this context";
}
// Generate the extra diagnostic.
PathDiagnosticLocation Pos(S, BRC.getSourceManager(),
N->getLocationContext());
return new PathDiagnosticEventPiece(Pos, OS.str(), true, nullptr);
}
static bool hasDefinition(const ObjCObjectPointerType *ObjPtr) {
const ObjCInterfaceDecl *Decl = ObjPtr->getInterfaceDecl();
if (!Decl)
return false;
return Decl->getDefinition();
}
// TODO: consider checking explicit casts?
void DynamicTypeChecker::checkPostStmt(const ImplicitCastExpr *CE,
CheckerContext &C) const {
// TODO: C++ support.
if (CE->getCastKind() != CK_BitCast)
return;
const MemRegion *Region = C.getSVal(CE).getAsRegion();
if (!Region)
return;
ProgramStateRef State = C.getState();
DynamicTypeInfo DynTypeInfo = getDynamicTypeInfo(State, Region);
if (!DynTypeInfo.isValid())
return;
QualType DynType = DynTypeInfo.getType();
QualType StaticType = CE->getType();
const auto *DynObjCType = DynType->getAs<ObjCObjectPointerType>();
const auto *StaticObjCType = StaticType->getAs<ObjCObjectPointerType>();
if (!DynObjCType || !StaticObjCType)
return;
if (!hasDefinition(DynObjCType) || !hasDefinition(StaticObjCType))
return;
ASTContext &ASTCtxt = C.getASTContext();
// Strip kindeofness to correctly detect subtyping relationships.
DynObjCType = DynObjCType->stripObjCKindOfTypeAndQuals(ASTCtxt);
StaticObjCType = StaticObjCType->stripObjCKindOfTypeAndQuals(ASTCtxt);
// Specialized objects are handled by the generics checker.
if (StaticObjCType->isSpecialized())
return;
if (ASTCtxt.canAssignObjCInterfaces(StaticObjCType, DynObjCType))
return;
if (DynTypeInfo.canBeASubClass() &&
ASTCtxt.canAssignObjCInterfaces(DynObjCType, StaticObjCType))
return;
reportTypeError(DynType, StaticType, Region, CE, C);
}
void ento::registerDynamicTypeChecker(CheckerManager &mgr) {
mgr.registerChecker<DynamicTypeChecker>();
}
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