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//===----- UninitializedObject.h ---------------------------------*- C++ -*-==//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// This file defines helper classes for UninitializedObjectChecker and
// documentation about the logic of it.
// The checker reports uninitialized fields in objects created after a
// constructor call.
// This checker has several options:
// - "Pedantic" (boolean). If its not set or is set to false, the checker
// won't emit warnings for objects that don't have at least one initialized
// field. This may be set with
// `-analyzer-config optin.cplusplus.UninitializedObject:Pedantic=true`.
// - "NotesAsWarnings" (boolean). If set to true, the checker will emit a
// warning for each uninitialized field, as opposed to emitting one warning
// per constructor call, and listing the uninitialized fields that belongs
// to it in notes. Defaults to false.
// `-analyzer-config \
// optin.cplusplus.UninitializedObject:NotesAsWarnings=true`.
// - "CheckPointeeInitialization" (boolean). If set to false, the checker will
// not analyze the pointee of pointer/reference fields, and will only check
// whether the object itself is initialized. Defaults to false.
// `-analyzer-config \
// optin.cplusplus.UninitializedObject:CheckPointeeInitialization=true`.
// TODO: With some clever heuristics, some pointers should be dereferenced
// by default. For example, if the pointee is constructed within the
// constructor call, it's reasonable to say that no external object
// references it, and we wouldn't generate multiple report on the same
// pointee.
// - "IgnoreRecordsWithField" (string). If supplied, the checker will not
// analyze structures that have a field with a name or type name that
// matches the given pattern. Defaults to "".
// `-analyzer-config \
// optin.cplusplus.UninitializedObject:IgnoreRecordsWithField="[Tt]ag|[Kk]ind"`.
// - "IgnoreGuardedFields" (boolean). If set to true, the checker will analyze
// _syntactically_ whether the found uninitialized object is used without a
// preceding assert call. Defaults to false.
// `-analyzer-config \
// optin.cplusplus.UninitializedObject:IgnoreGuardedFields=true`.
// Most of the following methods as well as the checker itself is defined in
// UninitializedObjectChecker.cpp.
// Some methods are implemented in UninitializedPointee.cpp, to reduce the
// complexity of the main checker file.
#include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
namespace clang {
namespace ento {
struct UninitObjCheckerOptions {
bool IsPedantic = false;
bool ShouldConvertNotesToWarnings = false;
bool CheckPointeeInitialization = false;
std::string IgnoredRecordsWithFieldPattern;
bool IgnoreGuardedFields = false;
/// A lightweight polymorphic wrapper around FieldRegion *. We'll use this
/// interface to store addinitional information about fields. As described
/// later, a list of these objects (i.e. "fieldchain") will be constructed and
/// used for printing note messages should an uninitialized value be found.
class FieldNode {
const FieldRegion *FR;
/// FieldNodes are never meant to be created on the heap, see
/// FindUninitializedFields::addFieldToUninits().
/* non-virtual */ ~FieldNode() = default;
FieldNode(const FieldRegion *FR) : FR(FR) {}
// We'll delete all of these special member functions to force the users of
// this interface to only store references to FieldNode objects in containers.
FieldNode() = delete;
FieldNode(const FieldNode &) = delete;
FieldNode(FieldNode &&) = delete;
FieldNode &operator=(const FieldNode &) = delete;
FieldNode &operator=(const FieldNode &&) = delete;
void Profile(llvm::FoldingSetNodeID &ID) const { ID.AddPointer(this); }
/// Helper method for uniqueing.
bool isSameRegion(const FieldRegion *OtherFR) const {
// Special FieldNode descendants may wrap nullpointers (for example if they
// describe a special relationship between two elements of the fieldchain)
// -- we wouldn't like to unique these objects.
if (FR == nullptr)
return false;
return FR == OtherFR;
const FieldRegion *getRegion() const { return FR; }
const FieldDecl *getDecl() const {
return FR->getDecl();
// When a fieldchain is printed, it will have the following format (without
// newline, indices are in order of insertion, from 1 to n):
// <note_message_n>'<prefix_n><prefix_n-1>...<prefix_1>
// this-><node_1><separator_1><node_2><separator_2>...<node_n>'
/// If this is the last element of the fieldchain, this method will print the
/// note message associated with it.
/// The note message should state something like "uninitialized field" or
/// "uninitialized pointee" etc.
virtual void printNoteMsg(llvm::raw_ostream &Out) const = 0;
/// Print any prefixes before the fieldchain. Could contain casts, etc.
virtual void printPrefix(llvm::raw_ostream &Out) const = 0;
/// Print the node. Should contain the name of the field stored in FR.
virtual void printNode(llvm::raw_ostream &Out) const = 0;
/// Print the separator. For example, fields may be separated with '.' or
/// "->".
virtual void printSeparator(llvm::raw_ostream &Out) const = 0;
virtual bool isBase() const { return false; }
/// Returns with Field's name. This is a helper function to get the correct name
/// even if Field is a captured lambda variable.
std::string getVariableName(const FieldDecl *Field);
/// Represents a field chain. A field chain is a list of fields where the first
/// element of the chain is the object under checking (not stored), and every
/// other element is a field, and the element that precedes it is the object
/// that contains it.
/// Note that this class is immutable (essentially a wrapper around an
/// ImmutableList), new FieldChainInfo objects may be created by member
/// functions such as add() and replaceHead().
class FieldChainInfo {
using FieldChain = llvm::ImmutableList<const FieldNode &>;
FieldChain::Factory &ChainFactory;
FieldChain Chain;
FieldChainInfo(FieldChain::Factory &F, FieldChain NewChain)
: FieldChainInfo(F) {
Chain = NewChain;
FieldChainInfo() = delete;
FieldChainInfo(FieldChain::Factory &F) : ChainFactory(F) {}
FieldChainInfo(const FieldChainInfo &Other) = default;
/// Constructs a new FieldChainInfo object with \p FN appended.
template <class FieldNodeT> FieldChainInfo add(const FieldNodeT &FN);
/// Constructs a new FieldChainInfo object with \p FN as the new head of the
/// list.
template <class FieldNodeT> FieldChainInfo replaceHead(const FieldNodeT &FN);
bool contains(const FieldRegion *FR) const;
bool isEmpty() const { return Chain.isEmpty(); }
const FieldNode &getHead() const { return Chain.getHead(); }
const FieldRegion *getUninitRegion() const { return getHead().getRegion(); }
void printNoteMsg(llvm::raw_ostream &Out) const;
using UninitFieldMap = std::map<const FieldRegion *, llvm::SmallString<50>>;
/// Searches for and stores uninitialized fields in a non-union object.
class FindUninitializedFields {
ProgramStateRef State;
const TypedValueRegion *const ObjectR;
const UninitObjCheckerOptions Opts;
bool IsAnyFieldInitialized = false;
FieldChainInfo::FieldChain::Factory ChainFactory;
/// A map for assigning uninitialized regions to note messages. For example,
/// struct A {
/// int x;
/// };
/// A a;
/// After analyzing `a`, the map will contain a pair for `a.x`'s region and
/// the note message "uninitialized field 'this->x'.
UninitFieldMap UninitFields;
/// Constructs the FindUninitializedField object, searches for and stores
/// uninitialized fields in R.
FindUninitializedFields(ProgramStateRef State,
const TypedValueRegion *const R,
const UninitObjCheckerOptions &Opts);
/// Returns with the modified state and a map of (uninitialized region,
/// note message) pairs.
std::pair<ProgramStateRef, const UninitFieldMap &> getResults() {
return {State, UninitFields};
/// Returns whether the analyzed region contains at least one initialized
/// field. Note that this includes subfields as well, not just direct ones,
/// and will return false if an uninitialized pointee is found with
/// CheckPointeeInitialization enabled.
bool isAnyFieldInitialized() { return IsAnyFieldInitialized; }
// For the purposes of this checker, we'll regard the analyzed region as a
// directed tree, where
// * the root is the object under checking
// * every node is an object that is
// - a union
// - a non-union record
// - dereferenceable (see isDereferencableType())
// - an array
// - of a primitive type (see isPrimitiveType())
// * the parent of each node is the object that contains it
// * every leaf is an array, a primitive object, a nullptr or an undefined
// pointer.
// Example:
// struct A {
// struct B {
// int x, y = 0;
// };
// B b;
// int *iptr = new int;
// B* bptr;
// A() {}
// };
// The directed tree:
// ->x
// /
// ->b--->y
// /
// A-->iptr->(int value)
// \
// ->bptr
// From this we'll construct a vector of fieldchains, where each fieldchain
// represents an uninitialized field. An uninitialized field may be a
// primitive object, a pointer, a pointee or a union without a single
// initialized field.
// In the above example, for the default constructor call we'll end up with
// these fieldchains:
// this->b.x
// this->iptr (pointee uninit)
// this->bptr (pointer uninit)
// We'll traverse each node of the above graph with the appropriate one of
// these methods:
/// Checks the region of a union object, and returns true if no field is
/// initialized within the region.
bool isUnionUninit(const TypedValueRegion *R);
/// Checks a region of a non-union object, and returns true if an
/// uninitialized field is found within the region.
bool isNonUnionUninit(const TypedValueRegion *R, FieldChainInfo LocalChain);
/// Checks a region of a pointer or reference object, and returns true if the
/// ptr/ref object itself or any field within the pointee's region is
/// uninitialized.
bool isDereferencableUninit(const FieldRegion *FR, FieldChainInfo LocalChain);
/// Returns true if the value of a primitive object is uninitialized.
bool isPrimitiveUninit(const SVal &V);
// Note that we don't have a method for arrays -- the elements of an array are
// often left uninitialized intentionally even when it is of a C++ record
// type, so we'll assume that an array is always initialized.
// TODO: Add a support for nonloc::LocAsInteger.
/// Processes LocalChain and attempts to insert it into UninitFields. Returns
/// true on success. Also adds the head of the list and \p PointeeR (if
/// supplied) to the GDM as already analyzed objects.
/// Since this class analyzes regions with recursion, we'll only store
/// references to temporary FieldNode objects created on the stack. This means
/// that after analyzing a leaf of the directed tree described above, the
/// elements LocalChain references will be destructed, so we can't store it
/// directly.
bool addFieldToUninits(FieldChainInfo LocalChain,
const MemRegion *PointeeR = nullptr);
/// Returns true if T is a primitive type. An object of a primitive type only
/// needs to be analyzed as much as checking whether their value is undefined.
inline bool isPrimitiveType(const QualType &T) {
return T->isBuiltinType() || T->isEnumeralType() ||
T->isFunctionType() || T->isAtomicType() ||
T->isVectorType() || T->isScalarType();
inline bool isDereferencableType(const QualType &T) {
return T->isAnyPointerType() || T->isReferenceType();
// Template method definitions.
template <class FieldNodeT>
inline FieldChainInfo FieldChainInfo::add(const FieldNodeT &FN) {
assert(!contains(FN.getRegion()) &&
"Can't add a field that is already a part of the "
"fieldchain! Is this a cyclic reference?");
FieldChainInfo NewChain = *this;
NewChain.Chain = ChainFactory.add(FN, Chain);
return NewChain;
template <class FieldNodeT>
inline FieldChainInfo FieldChainInfo::replaceHead(const FieldNodeT &FN) {
FieldChainInfo NewChain(ChainFactory, Chain.getTail());
return NewChain.add(FN);
} // end of namespace ento
} // end of namespace clang