UncheckedStatusOrAccessModel.cpp

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//===- UncheckedStatusOrAccessModel.cpp -----------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
 
#include "clang/Analysis/FlowSensitive/Models/UncheckedStatusOrAccessModel.h"
 
#include <cassert>
#include <utility>
 
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/TypeBase.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/ASTMatchers/ASTMatchers.h"
#include "clang/ASTMatchers/ASTMatchersInternal.h"
#include "clang/Analysis/CFG.h"
#include "clang/Analysis/FlowSensitive/CFGMatchSwitch.h"
#include "clang/Analysis/FlowSensitive/DataflowAnalysis.h"
#include "clang/Analysis/FlowSensitive/DataflowEnvironment.h"
#include "clang/Analysis/FlowSensitive/MatchSwitch.h"
#include "clang/Analysis/FlowSensitive/RecordOps.h"
#include "clang/Analysis/FlowSensitive/SmartPointerAccessorCaching.h"
#include "clang/Analysis/FlowSensitive/StorageLocation.h"
#include "clang/Analysis/FlowSensitive/Value.h"
#include "clang/Basic/LLVM.h"
#include "clang/Basic/SourceLocation.h"
#include "llvm/ADT/StringMap.h"
 
namespace clang::dataflow::statusor_model {
namespace {
 
using ::clang::ast_matchers::MatchFinder;
using ::clang::ast_matchers::StatementMatcher;
 
} // namespace
 
static bool namespaceEquals(const NamespaceDecl *NS,
                            clang::ArrayRef<clang::StringRef> NamespaceNames) {
  while (!NamespaceNames.empty() && NS) {
    if (NS->getName() != NamespaceNames.consume_back())
      return false;
    NS = dyn_cast_or_null<NamespaceDecl>(NS->getParent());
  }
  return NamespaceNames.empty() && !NS;
}
 
// TODO: move this to a proper place to share with the rest of clang
static bool isTypeNamed(QualType Type, clang::ArrayRef<clang::StringRef> NS,
                        StringRef Name) {
  if (Type.isNull())
    return false;
  if (auto *RD = Type->getAsRecordDecl())
    if (RD->getName() == Name)
      if (const auto *N = dyn_cast_or_null<NamespaceDecl>(RD->getDeclContext()))
        return namespaceEquals(N, NS);
  return false;
}
 
static bool isStatusOrOperatorBaseType(QualType Type) {
  return isTypeNamed(Type, {"absl", "internal_statusor"}, "OperatorBase");
}
 
static bool isSafeUnwrap(RecordStorageLocation *StatusOrLoc,
                         const Environment &Env) {
  if (!StatusOrLoc)
    return false;
  auto &StatusLoc = locForStatus(*StatusOrLoc);
  auto *OkVal = Env.get<BoolValue>(locForOk(StatusLoc));
  return OkVal != nullptr && Env.proves(OkVal->formula());
}
 
static ClassTemplateSpecializationDecl *
getStatusOrBaseClass(const QualType &Ty) {
  auto *RD = Ty->getAsCXXRecordDecl();
  if (RD == nullptr)
    return nullptr;
  if (isStatusOrType(Ty) ||
      // In case we are analyzing code under OperatorBase itself that uses
      // operator* (e.g. to implement operator->).
      isStatusOrOperatorBaseType(Ty))
    return cast<ClassTemplateSpecializationDecl>(RD);
  if (!RD->hasDefinition())
    return nullptr;
  for (const auto &Base : RD->bases())
    if (auto *QT = getStatusOrBaseClass(Base.getType()))
      return QT;
  return nullptr;
}
 
static QualType getStatusOrValueType(ClassTemplateSpecializationDecl *TRD) {
  return TRD->getTemplateArgs().get(0).getAsType();
}
 
static auto ofClassStatus() {
  using namespace ::clang::ast_matchers;
  return ofClass(hasName("::absl::Status"));
}
 
static auto isStatusMemberCallWithName(llvm::StringRef member_name) {
  using namespace ::clang::ast_matchers;
  return cxxMemberCallExpr(
      on(expr(unless(cxxThisExpr()))),
      callee(cxxMethodDecl(hasName(member_name), ofClassStatus())));
}
 
static auto isStatusOrMemberCallWithName(llvm::StringRef member_name) {
  using namespace ::clang::ast_matchers;
  return cxxMemberCallExpr(
      on(expr(unless(cxxThisExpr()))),
      callee(cxxMethodDecl(
          hasName(member_name),
          ofClass(anyOf(statusOrClass(), statusOrOperatorBaseClass())))));
}
 
static auto isStatusOrOperatorCallWithName(llvm::StringRef operator_name) {
  using namespace ::clang::ast_matchers;
  return cxxOperatorCallExpr(
      hasOverloadedOperatorName(operator_name),
      callee(cxxMethodDecl(
          ofClass(anyOf(statusOrClass(), statusOrOperatorBaseClass())))));
}
 
static auto valueCall() {
  using namespace ::clang::ast_matchers;
  return anyOf(isStatusOrMemberCallWithName("value"),
               isStatusOrMemberCallWithName("ValueOrDie"));
}
 
static auto valueOperatorCall() {
  using namespace ::clang::ast_matchers;
  return expr(anyOf(isStatusOrOperatorCallWithName("*"),
                    isStatusOrOperatorCallWithName("->")));
}
 
static auto isComparisonOperatorCall(llvm::StringRef operator_name) {
  using namespace ::clang::ast_matchers;
  return cxxOperatorCallExpr(
      hasOverloadedOperatorName(operator_name), argumentCountIs(2),
      hasArgument(0, anyOf(hasType(statusType()), hasType(statusOrType()))),
      hasArgument(1, anyOf(hasType(statusType()), hasType(statusOrType()))));
}
 
static auto isOkStatusCall() {
  using namespace ::clang::ast_matchers;
  return callExpr(callee(functionDecl(hasName("::absl::OkStatus"))));
}
 
static auto isNotOkStatusCall() {
  using namespace ::clang::ast_matchers;
  return callExpr(callee(functionDecl(hasAnyName(
      "::absl::AbortedError", "::absl::AlreadyExistsError",
      "::absl::CancelledError", "::absl::DataLossError",
      "::absl::DeadlineExceededError", "::absl::FailedPreconditionError",
      "::absl::InternalError", "::absl::InvalidArgumentError",
      "::absl::NotFoundError", "::absl::OutOfRangeError",
      "::absl::PermissionDeniedError", "::absl::ResourceExhaustedError",
      "::absl::UnauthenticatedError", "::absl::UnavailableError",
      "::absl::UnimplementedError", "::absl::UnknownError"))));
}
 
static auto isPointerComparisonOperatorCall(std::string operator_name) {
  using namespace ::clang::ast_matchers;
  return binaryOperator(hasOperatorName(operator_name),
                        hasLHS(hasType(hasCanonicalType(pointerType(
                            pointee(anyOf(statusOrType(), statusType())))))),
                        hasRHS(hasType(hasCanonicalType(pointerType(
                            pointee(anyOf(statusOrType(), statusType())))))));
}
 
// The nullPointerConstant in the two matchers below is to support
// absl::StatusOr<void*> X = nullptr.
// nullptr does not match the bound type.
// TODO: be less restrictive around convertible types in general.
static auto isStatusOrValueAssignmentCall() {
  using namespace ::clang::ast_matchers;
  return cxxOperatorCallExpr(
      hasOverloadedOperatorName("="),
      callee(cxxMethodDecl(ofClass(statusOrClass()))),
      hasArgument(1, anyOf(hasType(hasUnqualifiedDesugaredType(
                               type(equalsBoundNode("T")))),
                           nullPointerConstant())));
}
 
static auto isStatusOrValueConstructor() {
  using namespace ::clang::ast_matchers;
  return cxxConstructExpr(
      hasType(statusOrType()),
      hasArgument(0,
                  anyOf(hasType(hasCanonicalType(type(equalsBoundNode("T")))),
                        nullPointerConstant(),
                        hasType(namedDecl(hasAnyName("absl::in_place_t",
                                                     "std::in_place_t"))))));
}
 
static auto isStatusOrConstructor() {
  using namespace ::clang::ast_matchers;
  return cxxConstructExpr(hasType(statusOrType()));
}
 
static auto isStatusConstructor() {
  using namespace ::clang::ast_matchers;
  return cxxConstructExpr(hasType(statusType()));
}
static auto isLoggingGetReferenceableValueCall() {
  using namespace ::clang::ast_matchers;
  return callExpr(callee(
      functionDecl(hasName("::absl::log_internal::GetReferenceableValue"))));
}
 
static auto isLoggingCheckEqImpl() {
  using namespace ::clang::ast_matchers;
  return callExpr(
      callee(functionDecl(hasName("::absl::log_internal::Check_EQImpl"))));
}
 
static auto isAsStatusCallWithStatus() {
  using namespace ::clang::ast_matchers;
  return callExpr(
      callee(functionDecl(hasName("::absl::log_internal::AsStatus"))),
      hasArgument(0, hasType(statusClass())));
}
 
static auto isAsStatusCallWithStatusOr() {
  using namespace ::clang::ast_matchers;
  return callExpr(
      callee(functionDecl(hasName("::absl::log_internal::AsStatus"))),
      hasArgument(0, hasType(statusOrType())));
}
 
static auto possiblyReferencedStatusOrType() {
  using namespace ::clang::ast_matchers;
  return anyOf(statusOrType(), referenceType(pointee(statusOrType())));
}
 
static auto isConstAccessorMemberCall() {
  using namespace ::clang::ast_matchers;
  return cxxMemberCallExpr(callee(cxxMethodDecl(
      parameterCountIs(0), isConst(),
      returns(hasCanonicalType(anyOf(referenceType(), recordType()))))));
}
 
static auto isConstAccessorMemberOperatorCall() {
  using namespace ::clang::ast_matchers;
  return cxxOperatorCallExpr(callee(cxxMethodDecl(
      parameterCountIs(0), isConst(),
      returns(hasCanonicalType(anyOf(referenceType(), recordType()))))));
}
 
static auto isConstPointerAccessorMemberCall() {
  using namespace ::clang::ast_matchers;
  return cxxMemberCallExpr(callee(
      cxxMethodDecl(parameterCountIs(0), isConst(), returns(pointerType()))));
}
 
static auto isConstPointerAccessorMemberOperatorCall() {
  using namespace ::clang::ast_matchers;
  return cxxOperatorCallExpr(callee(
      cxxMethodDecl(parameterCountIs(0), isConst(), returns(pointerType()))));
}
 
static auto isNonConstMemberCall() {
  using namespace ::clang::ast_matchers;
  return cxxMemberCallExpr(callee(cxxMethodDecl(unless(isConst()))));
}
 
static auto isNonConstMemberOperatorCall() {
  using namespace ::clang::ast_matchers;
  return cxxOperatorCallExpr(callee(cxxMethodDecl(unless(isConst()))));
}
 
static auto isMakePredicateFormatterFromIsOkMatcherCall() {
  using namespace ::clang::ast_matchers;
  return callExpr(
      callee(functionDecl(
          hasName("::testing::internal::MakePredicateFormatterFromMatcher"))),
      hasArgument(
          0, hasType(cxxRecordDecl(hasAnyName(
                 "::testing::status::internal_status::IsOkMatcher",
                 "::absl_testing::status_internal::IsOkMatcher",
                 "::testing::status::internal_status::IsOkAndHoldsMatcher",
                 "::absl_testing::status_internal::IsOkAndHoldsMatcher")))));
}
 
static auto isStatusIsOkMatcherCall() {
  using namespace ::clang::ast_matchers;
  return callExpr(callee(functionDecl(hasAnyName(
                      "::testing::status::StatusIs", "absl_testing::StatusIs",
                      "::testing::status::CanonicalStatusIs",
                      "::absl_testing::CanonicalStatusIs"))),
                  hasArgument(0, declRefExpr(to(enumConstantDecl(hasAnyName(
                                     "::absl::StatusCode::kOk", "OK"))))));
}
 
static auto isMakePredicateFormatterFromStatusIsMatcherCall() {
  using namespace ::clang::ast_matchers;
  return callExpr(
      callee(functionDecl(
          hasName("::testing::internal::MakePredicateFormatterFromMatcher"))),
      hasArgument(0, hasType(cxxRecordDecl(hasAnyName(
                         "::testing::status::internal_status::StatusIsMatcher",
                         "::testing::status::internal_status::"
                         "CanonicalStatusIsMatcher",
                         "::absl_testing::status_internal::StatusIsMatcher",
                         "::absl_testing::status_internal::"
                         "CanonicalStatusIsMatcher")))));
}
 
static auto isPredicateFormatterFromStatusMatcherCall() {
  using namespace ::clang::ast_matchers;
  return cxxOperatorCallExpr(
      hasOverloadedOperatorName("()"),
      callee(cxxMethodDecl(ofClass(
          hasName("testing::internal::PredicateFormatterFromMatcher")))),
      hasArgument(2, hasType(statusType())));
}
 
static auto isPredicateFormatterFromStatusOrMatcherCall() {
  using namespace ::clang::ast_matchers;
  return cxxOperatorCallExpr(
      hasOverloadedOperatorName("()"),
      callee(cxxMethodDecl(ofClass(
          hasName("testing::internal::PredicateFormatterFromMatcher")))),
      hasArgument(2, hasType(statusOrType())));
}
 
static auto isAssertionResultOperatorBoolCall() {
  using namespace ::clang::ast_matchers;
  return cxxMemberCallExpr(
      on(expr(unless(cxxThisExpr()))),
      callee(cxxMethodDecl(hasName("operator bool"),
                           ofClass(hasName("testing::AssertionResult")))));
}
 
static auto isAssertionResultConstructFromBoolCall() {
  using namespace ::clang::ast_matchers;
  return cxxConstructExpr(
      hasType(recordDecl(hasName("testing::AssertionResult"))),
      hasArgument(0, hasType(booleanType())));
}
 
static auto isStatusOrReturningCall() {
  using namespace ::clang::ast_matchers;
  return callExpr(
      callee(functionDecl(returns(possiblyReferencedStatusOrType()))));
}
 
static auto isStatusOrPtrReturningCall() {
  using namespace ::clang::ast_matchers;
  return callExpr(callee(functionDecl(returns(hasUnqualifiedDesugaredType(
      pointerType(pointee(possiblyReferencedStatusOrType())))))));
}
 
static auto isStatusPtrReturningCall() {
  using namespace ::clang::ast_matchers;
  return callExpr(callee(functionDecl(returns(hasUnqualifiedDesugaredType(
      pointerType(pointee(hasUnqualifiedDesugaredType(
          recordType(hasDeclaration(statusClass()))))))))));
}
 
static auto
buildDiagnoseMatchSwitch(const UncheckedStatusOrAccessModelOptions &Options) {
  return CFGMatchSwitchBuilder<const Environment,
                               llvm::SmallVector<SourceLocation>>()
      // StatusOr::value, StatusOr::ValueOrDie
      .CaseOfCFGStmt<CXXMemberCallExpr>(
          valueCall(),
          [](const CXXMemberCallExpr *E,
             const ast_matchers::MatchFinder::MatchResult &,
             const Environment &Env) {
            if (!isSafeUnwrap(getImplicitObjectLocation(*E, Env), Env))
              return llvm::SmallVector<SourceLocation>({E->getExprLoc()});
            return llvm::SmallVector<SourceLocation>();
          })
 
      // StatusOr::operator*, StatusOr::operator->
      .CaseOfCFGStmt<CXXOperatorCallExpr>(
          valueOperatorCall(),
          [](const CXXOperatorCallExpr *E,
             const ast_matchers::MatchFinder::MatchResult &,
             const Environment &Env) {
            RecordStorageLocation *StatusOrLoc =
                Env.get<RecordStorageLocation>(*E->getArg(0));
            if (!isSafeUnwrap(StatusOrLoc, Env))
              return llvm::SmallVector<SourceLocation>({E->getOperatorLoc()});
            return llvm::SmallVector<SourceLocation>();
          })
      .Build();
}
 
UncheckedStatusOrAccessDiagnoser::UncheckedStatusOrAccessDiagnoser(
    UncheckedStatusOrAccessModelOptions Options)
    : DiagnoseMatchSwitch(buildDiagnoseMatchSwitch(Options)) {}
 
llvm::SmallVector<SourceLocation> UncheckedStatusOrAccessDiagnoser::operator()(
    const CFGElement &Elt, ASTContext &Ctx,
    const TransferStateForDiagnostics<UncheckedStatusOrAccessModel::Lattice>
        &State) {
  return DiagnoseMatchSwitch(Elt, Ctx, State.Env);
}
 
BoolValue &initializeStatus(RecordStorageLocation &StatusLoc,
                            Environment &Env) {
  auto &OkVal = Env.makeAtomicBoolValue();
  Env.setValue(locForOk(StatusLoc), OkVal);
  return OkVal;
}
 
BoolValue &initializeStatusOr(RecordStorageLocation &StatusOrLoc,
                              Environment &Env) {
  return initializeStatus(locForStatus(StatusOrLoc), Env);
}
 
clang::ast_matchers::DeclarationMatcher statusOrClass() {
  using namespace ::clang::ast_matchers;
  return classTemplateSpecializationDecl(
      hasName("absl::StatusOr"),
      hasTemplateArgument(0, refersToType(type().bind("T"))));
}
 
clang::ast_matchers::DeclarationMatcher statusClass() {
  using namespace ::clang::ast_matchers;
  return cxxRecordDecl(hasName("absl::Status"));
}
 
clang::ast_matchers::DeclarationMatcher statusOrOperatorBaseClass() {
  using namespace ::clang::ast_matchers;
  return classTemplateSpecializationDecl(
      hasName("absl::internal_statusor::OperatorBase"));
}
 
clang::ast_matchers::TypeMatcher statusOrType() {
  using namespace ::clang::ast_matchers;
  return hasCanonicalType(qualType(hasDeclaration(statusOrClass())));
}
 
clang::ast_matchers::TypeMatcher statusType() {
  using namespace ::clang::ast_matchers;
  return hasCanonicalType(qualType(hasDeclaration(statusClass())));
}
 
bool isStatusOrType(QualType Type) {
  return isTypeNamed(Type, {"absl"}, "StatusOr");
}
 
bool isStatusType(QualType Type) {
  return isTypeNamed(Type, {"absl"}, "Status");
}
 
static bool isPredicateFormatterFromMatcherType(QualType Type) {
  return isTypeNamed(Type, {"testing", "internal"},
                     "PredicateFormatterFromMatcher");
}
 
static bool isAssertionResultType(QualType Type) {
  return isTypeNamed(Type, {"testing"}, "AssertionResult");
}
 
static bool isStatusIsMatcherType(QualType Type) {
  return isTypeNamed(Type, {"testing", "status", "internal_status"},
                     "StatusIsMatcher") ||
         isTypeNamed(Type, {"testing", "status", "internal_status"},
                     "CanonicalStatusIsMatcher") ||
         isTypeNamed(Type, {"absl_testing", "status_internal"},
                     "StatusIsMatcher") ||
         isTypeNamed(Type, {"absl_testing", "status_internal"},
                     "CanonicalStatusIsMatcher");
}
 
llvm::StringMap<QualType> getSyntheticFields(QualType Ty, QualType StatusType,
                                             const CXXRecordDecl &RD) {
  if (auto *TRD = getStatusOrBaseClass(Ty))
    return {{"status", StatusType}, {"value", getStatusOrValueType(TRD)}};
  if (isStatusType(Ty) || (RD.hasDefinition() &&
                           RD.isDerivedFrom(StatusType->getAsCXXRecordDecl())))
    return {{"ok", RD.getASTContext().BoolTy}};
  if (isAssertionResultType(Ty))
    return {{"ok", RD.getASTContext().BoolTy}};
  if (isPredicateFormatterFromMatcherType(Ty))
    return {{"ok_predicate", RD.getASTContext().BoolTy}};
  if (isStatusIsMatcherType(Ty))
    return {{"ok_matcher", RD.getASTContext().BoolTy}};
  return {};
}
 
RecordStorageLocation &locForStatus(RecordStorageLocation &StatusOrLoc) {
  return cast<RecordStorageLocation>(StatusOrLoc.getSyntheticField("status"));
}
 
StorageLocation &locForOk(RecordStorageLocation &StatusLoc) {
  return StatusLoc.getSyntheticField("ok");
}
 
BoolValue &valForOk(RecordStorageLocation &StatusLoc, Environment &Env) {
  if (auto *Val = Env.get<BoolValue>(locForOk(StatusLoc)))
    return *Val;
  return initializeStatus(StatusLoc, Env);
}
static StorageLocation &locForOkPredicate(RecordStorageLocation &StatusLoc) {
  return StatusLoc.getSyntheticField("ok_predicate");
}
 
static StorageLocation &locForOkMatcher(RecordStorageLocation &StatusLoc) {
  return StatusLoc.getSyntheticField("ok_matcher");
}
 
static void transferStatusOrOkCall(const CXXMemberCallExpr *Expr,
                                   const MatchFinder::MatchResult &,
                                   LatticeTransferState &State) {
  RecordStorageLocation *StatusOrLoc =
      getImplicitObjectLocation(*Expr, State.Env);
  if (StatusOrLoc == nullptr)
    return;
 
  auto &OkVal = valForOk(locForStatus(*StatusOrLoc), State.Env);
  State.Env.setValue(*Expr, OkVal);
}
 
static void transferStatusCall(const CXXMemberCallExpr *Expr,
                               const MatchFinder::MatchResult &,
                               LatticeTransferState &State) {
  RecordStorageLocation *StatusOrLoc =
      getImplicitObjectLocation(*Expr, State.Env);
  if (StatusOrLoc == nullptr)
    return;
 
  RecordStorageLocation &StatusLoc = locForStatus(*StatusOrLoc);
 
  if (State.Env.getValue(locForOk(StatusLoc)) == nullptr)
    initializeStatusOr(*StatusOrLoc, State.Env);
 
  if (Expr->isPRValue())
    copyRecord(StatusLoc, State.Env.getResultObjectLocation(*Expr), State.Env);
  else
    State.Env.setStorageLocation(*Expr, StatusLoc);
}
 
static void transferStatusOkCall(const CXXMemberCallExpr *Expr,
                                 const MatchFinder::MatchResult &,
                                 LatticeTransferState &State) {
  RecordStorageLocation *StatusLoc =
      getImplicitObjectLocation(*Expr, State.Env);
  if (StatusLoc == nullptr)
    return;
 
  if (Value *Val = State.Env.getValue(locForOk(*StatusLoc)))
    State.Env.setValue(*Expr, *Val);
}
 
static void transferStatusUpdateCall(const CXXMemberCallExpr *Expr,
                                     const MatchFinder::MatchResult &,
                                     LatticeTransferState &State) {
  // S.Update(OtherS) sets S to the error code of OtherS if it is OK,
  // otherwise does nothing.
  assert(Expr->getNumArgs() == 1);
  auto *Arg = Expr->getArg(0);
  RecordStorageLocation *ArgRecord =
      Arg->isPRValue() ? &State.Env.getResultObjectLocation(*Arg)
                       : State.Env.get<RecordStorageLocation>(*Arg);
  RecordStorageLocation *ThisLoc = getImplicitObjectLocation(*Expr, State.Env);
  if (ThisLoc == nullptr || ArgRecord == nullptr)
    return;
 
  auto &ThisOkVal = valForOk(*ThisLoc, State.Env);
  auto &ArgOkVal = valForOk(*ArgRecord, State.Env);
  auto &A = State.Env.arena();
  auto &NewVal = State.Env.makeAtomicBoolValue();
  State.Env.assume(A.makeImplies(A.makeNot(ThisOkVal.formula()),
                                 A.makeNot(NewVal.formula())));
  State.Env.assume(A.makeImplies(NewVal.formula(), ArgOkVal.formula()));
  State.Env.setValue(locForOk(*ThisLoc), NewVal);
}
 
static BoolValue *evaluateStatusEquality(RecordStorageLocation &LhsStatusLoc,
                                         RecordStorageLocation &RhsStatusLoc,
                                         Environment &Env) {
  auto &A = Env.arena();
  // Logically, a Status object is composed of an error code that could take one
  // of multiple possible values, including the "ok" value. We track whether a
  // Status object has an "ok" value and represent this as an `ok` bit. Equality
  // of Status objects compares their error codes. Therefore, merely comparing
  // the `ok` bits isn't sufficient: when two Status objects are assigned non-ok
  // error codes the equality of their respective error codes matters. Since we
  // only track the `ok` bits, we can't make any conclusions about equality when
  // we know that two Status objects have non-ok values.
 
  auto &LhsOkVal = valForOk(LhsStatusLoc, Env);
  auto &RhsOkVal = valForOk(RhsStatusLoc, Env);
 
  auto &Res = Env.makeAtomicBoolValue();
 
  // lhs && rhs => res (a.k.a. !res => !lhs || !rhs)
  Env.assume(A.makeImplies(A.makeAnd(LhsOkVal.formula(), RhsOkVal.formula()),
                           Res.formula()));
  // res => (lhs == rhs)
  Env.assume(A.makeImplies(
      Res.formula(), A.makeEquals(LhsOkVal.formula(), RhsOkVal.formula())));
 
  return &Res;
}
 
static BoolValue *
evaluateStatusOrEquality(RecordStorageLocation &LhsStatusOrLoc,
                         RecordStorageLocation &RhsStatusOrLoc,
                         Environment &Env) {
  auto &A = Env.arena();
  // Logically, a StatusOr<T> object is composed of two values - a Status and a
  // value of type T. Equality of StatusOr objects compares both values.
  // Therefore, merely comparing the `ok` bits of the Status values isn't
  // sufficient. When two StatusOr objects are engaged, the equality of their
  // respective values of type T matters. Similarly, when two StatusOr objects
  // have Status values that have non-ok error codes, the equality of the error
  // codes matters. Since we only track the `ok` bits of the Status values, we
  // can't make any conclusions about equality when we know that two StatusOr
  // objects are engaged or when their Status values contain non-ok error codes.
  auto &LhsOkVal = valForOk(locForStatus(LhsStatusOrLoc), Env);
  auto &RhsOkVal = valForOk(locForStatus(RhsStatusOrLoc), Env);
  auto &res = Env.makeAtomicBoolValue();
 
  // res => (lhs == rhs)
  Env.assume(A.makeImplies(
      res.formula(), A.makeEquals(LhsOkVal.formula(), RhsOkVal.formula())));
  return &res;
}
 
static BoolValue *evaluateEquality(const Expr *LhsExpr, const Expr *RhsExpr,
                                   Environment &Env) {
  // Check the type of both sides in case an operator== is added that admits
  // different types.
  if (isStatusOrType(LhsExpr->getType()) &&
      isStatusOrType(RhsExpr->getType())) {
    auto *LhsStatusOrLoc = Env.get<RecordStorageLocation>(*LhsExpr);
    if (LhsStatusOrLoc == nullptr)
      return nullptr;
    auto *RhsStatusOrLoc = Env.get<RecordStorageLocation>(*RhsExpr);
    if (RhsStatusOrLoc == nullptr)
      return nullptr;
 
    return evaluateStatusOrEquality(*LhsStatusOrLoc, *RhsStatusOrLoc, Env);
  }
  if (isStatusType(LhsExpr->getType()) && isStatusType(RhsExpr->getType())) {
    auto *LhsStatusLoc = Env.get<RecordStorageLocation>(*LhsExpr);
    if (LhsStatusLoc == nullptr)
      return nullptr;
 
    auto *RhsStatusLoc = Env.get<RecordStorageLocation>(*RhsExpr);
    if (RhsStatusLoc == nullptr)
      return nullptr;
 
    return evaluateStatusEquality(*LhsStatusLoc, *RhsStatusLoc, Env);
  }
  return nullptr;
}
 
static void transferComparisonOperator(const CXXOperatorCallExpr *Expr,
                                       LatticeTransferState &State,
                                       bool IsNegative) {
  auto *LhsAndRhsVal =
      evaluateEquality(Expr->getArg(0), Expr->getArg(1), State.Env);
  if (LhsAndRhsVal == nullptr)
    return;
 
  if (IsNegative)
    State.Env.setValue(*Expr, State.Env.makeNot(*LhsAndRhsVal));
  else
    State.Env.setValue(*Expr, *LhsAndRhsVal);
}
 
static RecordStorageLocation *getPointeeLocation(const Expr &Expr,
                                                 Environment &Env) {
  if (auto *PointerVal = Env.get<PointerValue>(Expr))
    return dyn_cast<RecordStorageLocation>(&PointerVal->getPointeeLoc());
  return nullptr;
}
 
static BoolValue *evaluatePointerEquality(const Expr *LhsExpr,
                                          const Expr *RhsExpr,
                                          Environment &Env) {
  assert(LhsExpr->getType()->isPointerType());
  assert(RhsExpr->getType()->isPointerType());
  RecordStorageLocation *LhsStatusLoc = nullptr;
  RecordStorageLocation *RhsStatusLoc = nullptr;
  if (isStatusOrType(LhsExpr->getType()->getPointeeType()) &&
      isStatusOrType(RhsExpr->getType()->getPointeeType())) {
    auto *LhsStatusOrLoc = getPointeeLocation(*LhsExpr, Env);
    auto *RhsStatusOrLoc = getPointeeLocation(*RhsExpr, Env);
    if (LhsStatusOrLoc == nullptr || RhsStatusOrLoc == nullptr)
      return nullptr;
    LhsStatusLoc = &locForStatus(*LhsStatusOrLoc);
    RhsStatusLoc = &locForStatus(*RhsStatusOrLoc);
  } else if (isStatusType(LhsExpr->getType()->getPointeeType()) &&
             isStatusType(RhsExpr->getType()->getPointeeType())) {
    LhsStatusLoc = getPointeeLocation(*LhsExpr, Env);
    RhsStatusLoc = getPointeeLocation(*RhsExpr, Env);
  }
  if (LhsStatusLoc == nullptr || RhsStatusLoc == nullptr)
    return nullptr;
  auto &LhsOkVal = valForOk(*LhsStatusLoc, Env);
  auto &RhsOkVal = valForOk(*RhsStatusLoc, Env);
  auto &Res = Env.makeAtomicBoolValue();
  auto &A = Env.arena();
  Env.assume(A.makeImplies(
      Res.formula(), A.makeEquals(LhsOkVal.formula(), RhsOkVal.formula())));
  return &Res;
}
 
static void transferPointerComparisonOperator(const BinaryOperator *Expr,
                                              LatticeTransferState &State,
                                              bool IsNegative) {
  auto *LhsAndRhsVal =
      evaluatePointerEquality(Expr->getLHS(), Expr->getRHS(), State.Env);
  if (LhsAndRhsVal == nullptr)
    return;
 
  if (IsNegative)
    State.Env.setValue(*Expr, State.Env.makeNot(*LhsAndRhsVal));
  else
    State.Env.setValue(*Expr, *LhsAndRhsVal);
}
 
static void transferOkStatusCall(const CallExpr *Expr,
                                 const MatchFinder::MatchResult &,
                                 LatticeTransferState &State) {
  auto &OkVal =
      initializeStatus(State.Env.getResultObjectLocation(*Expr), State.Env);
  State.Env.assume(OkVal.formula());
}
 
static void transferNotOkStatusCall(const CallExpr *Expr,
                                    const MatchFinder::MatchResult &,
                                    LatticeTransferState &State) {
  auto &OkVal =
      initializeStatus(State.Env.getResultObjectLocation(*Expr), State.Env);
  auto &A = State.Env.arena();
  State.Env.assume(A.makeNot(OkVal.formula()));
}
 
static void transferEmplaceCall(const CXXMemberCallExpr *Expr,
                                const MatchFinder::MatchResult &,
                                LatticeTransferState &State) {
  RecordStorageLocation *StatusOrLoc =
      getImplicitObjectLocation(*Expr, State.Env);
  if (StatusOrLoc == nullptr)
    return;
 
  auto &OkVal = valForOk(locForStatus(*StatusOrLoc), State.Env);
  State.Env.assume(OkVal.formula());
}
 
static void transferValueAssignmentCall(const CXXOperatorCallExpr *Expr,
                                        const MatchFinder::MatchResult &,
                                        LatticeTransferState &State) {
  assert(Expr->getNumArgs() > 1);
 
  auto *StatusOrLoc = State.Env.get<RecordStorageLocation>(*Expr->getArg(0));
  if (StatusOrLoc == nullptr)
    return;
 
  auto &OkVal = initializeStatusOr(*StatusOrLoc, State.Env);
  State.Env.assume(OkVal.formula());
}
 
static void transferValueConstructor(const CXXConstructExpr *Expr,
                                     const MatchFinder::MatchResult &,
                                     LatticeTransferState &State) {
  auto &OkVal =
      initializeStatusOr(State.Env.getResultObjectLocation(*Expr), State.Env);
  State.Env.assume(OkVal.formula());
}
 
static void transferStatusOrConstructor(const CXXConstructExpr *Expr,
                                        const MatchFinder::MatchResult &,
                                        LatticeTransferState &State) {
  RecordStorageLocation &StatusOrLoc = State.Env.getResultObjectLocation(*Expr);
  RecordStorageLocation &StatusLoc = locForStatus(StatusOrLoc);
 
  if (State.Env.getValue(locForOk(StatusLoc)) == nullptr)
    initializeStatusOr(StatusOrLoc, State.Env);
}
 
static void transferStatusConstructor(const CXXConstructExpr *Expr,
                                      const MatchFinder::MatchResult &,
                                      LatticeTransferState &State) {
  RecordStorageLocation &StatusLoc = State.Env.getResultObjectLocation(*Expr);
 
  if (State.Env.getValue(locForOk(StatusLoc)) == nullptr)
    initializeStatus(StatusLoc, State.Env);
}
static void
transferLoggingGetReferenceableValueCall(const CallExpr *Expr,
                                         const MatchFinder::MatchResult &,
                                         LatticeTransferState &State) {
  assert(Expr->getNumArgs() == 1);
  if (Expr->getArg(0)->isPRValue())
    return;
  auto *ArgLoc = State.Env.getStorageLocation(*Expr->getArg(0));
  if (ArgLoc == nullptr)
    return;
 
  State.Env.setStorageLocation(*Expr, *ArgLoc);
}
 
static void transferLoggingCheckEqImpl(const CallExpr *Expr,
                                       const MatchFinder::MatchResult &,
                                       LatticeTransferState &State) {
  assert(Expr->getNumArgs() > 2);
 
  auto *EqVal = evaluateEquality(Expr->getArg(0), Expr->getArg(1), State.Env);
  if (EqVal == nullptr)
    return;
 
  // Consider modelling this more accurately instead of assigning BoolValue
  // as the value of an expression of pointer type.
  // For now, this is being handled in transferPointerToBoolean.
  State.Env.setValue(*Expr, State.Env.makeNot(*EqVal));
}
 
static void transferAsStatusCallWithStatus(const CallExpr *Expr,
                                           const MatchFinder::MatchResult &,
                                           LatticeTransferState &State) {
  assert(Expr->getNumArgs() == 1);
 
  auto *ArgLoc = State.Env.get<RecordStorageLocation>(*Expr->getArg(0));
  if (ArgLoc == nullptr)
    return;
 
  if (State.Env.getValue(locForOk(*ArgLoc)) == nullptr)
    initializeStatus(*ArgLoc, State.Env);
 
  auto &ExprVal = State.Env.create<PointerValue>(*ArgLoc);
  State.Env.setValue(*Expr, ExprVal);
}
 
static void transferAsStatusCallWithStatusOr(const CallExpr *Expr,
                                             const MatchFinder::MatchResult &,
                                             LatticeTransferState &State) {
  assert(Expr->getNumArgs() == 1);
 
  auto *ArgLoc = State.Env.get<RecordStorageLocation>(*Expr->getArg(0));
  if (ArgLoc == nullptr)
    return;
 
  RecordStorageLocation &StatusLoc = locForStatus(*ArgLoc);
 
  if (State.Env.getValue(locForOk(StatusLoc)) == nullptr)
    initializeStatusOr(*ArgLoc, State.Env);
 
  auto &ExprVal = State.Env.create<PointerValue>(StatusLoc);
  State.Env.setValue(*Expr, ExprVal);
}
 
static void transferPointerToBoolean(const ImplicitCastExpr *Expr,
                                     const MatchFinder::MatchResult &,
                                     LatticeTransferState &State) {
  if (auto *SubExprVal =
          dyn_cast_or_null<BoolValue>(State.Env.getValue(*Expr->getSubExpr())))
    State.Env.setValue(*Expr, *SubExprVal);
}
 
static void transferStatusOrReturningCall(const CallExpr *Expr,
                                          LatticeTransferState &State) {
  RecordStorageLocation *StatusOrLoc =
      Expr->isPRValue() ? &State.Env.getResultObjectLocation(*Expr)
                        : State.Env.get<RecordStorageLocation>(*Expr);
  if (StatusOrLoc != nullptr &&
      State.Env.getValue(locForOk(locForStatus(*StatusOrLoc))) == nullptr)
    initializeStatusOr(*StatusOrLoc, State.Env);
}
 
static bool doHandleConstAccessorMemberCall(
    const CallExpr *Expr, RecordStorageLocation *RecordLoc,
    const MatchFinder::MatchResult &Result, LatticeTransferState &State) {
  if (RecordLoc == nullptr)
    return false;
  const FunctionDecl *DirectCallee = Expr->getDirectCallee();
  if (DirectCallee == nullptr)
    return false;
  StorageLocation &Loc =
      State.Lattice.getOrCreateConstMethodReturnStorageLocation(
          *RecordLoc, DirectCallee, State.Env, [&](StorageLocation &Loc) {
            if (isStatusOrType(Expr->getType()))
              initializeStatusOr(cast<RecordStorageLocation>(Loc), State.Env);
          });
  if (Expr->isPRValue()) {
    auto &ResultLoc = State.Env.getResultObjectLocation(*Expr);
    copyRecord(cast<RecordStorageLocation>(Loc), ResultLoc, State.Env);
  } else {
    State.Env.setStorageLocation(*Expr, Loc);
  }
  return true;
}
 
static void handleConstAccessorMemberCall(
    const CallExpr *Expr, RecordStorageLocation *RecordLoc,
    const MatchFinder::MatchResult &Result, LatticeTransferState &State) {
  if (!doHandleConstAccessorMemberCall(Expr, RecordLoc, Result, State) &&
      isStatusOrType(Expr->getType()))
    transferStatusOrReturningCall(Expr, State);
}
static void handleConstPointerAccessorMemberCall(
    const CallExpr *Expr, RecordStorageLocation *RecordLoc,
    const MatchFinder::MatchResult &Result, LatticeTransferState &State) {
  if (RecordLoc == nullptr)
    return;
  auto *Val = State.Lattice.getOrCreateConstMethodReturnValue(*RecordLoc, Expr,
                                                              State.Env);
  State.Env.setValue(*Expr, *Val);
}
 
static void
transferConstAccessorMemberCall(const CXXMemberCallExpr *Expr,
                                const MatchFinder::MatchResult &Result,
                                LatticeTransferState &State) {
  auto Type = Expr->getType();
  if (!Type->isRecordType() && !Type->isReferenceType())
    return;
  handleConstAccessorMemberCall(
      Expr, getImplicitObjectLocation(*Expr, State.Env), Result, State);
}
 
static void
transferConstAccessorMemberOperatorCall(const CXXOperatorCallExpr *Expr,
                                        const MatchFinder::MatchResult &Result,
                                        LatticeTransferState &State) {
  auto Type = Expr->getArg(0)->getType();
  if (!Type->isRecordType() && !Type->isReferenceType())
    return;
  auto *RecordLoc = cast_or_null<RecordStorageLocation>(
      State.Env.getStorageLocation(*Expr->getArg(0)));
  handleConstAccessorMemberCall(Expr, RecordLoc, Result, State);
}
 
static void
transferConstPointerAccessorMemberCall(const CXXMemberCallExpr *Expr,
                                       const MatchFinder::MatchResult &Result,
                                       LatticeTransferState &State) {
  handleConstPointerAccessorMemberCall(
      Expr, getImplicitObjectLocation(*Expr, State.Env), Result, State);
}
 
static void transferConstPointerAccessorMemberOperatorCall(
    const CXXOperatorCallExpr *Expr, const MatchFinder::MatchResult &Result,
    LatticeTransferState &State) {
  auto *RecordLoc = cast_or_null<RecordStorageLocation>(
      State.Env.getStorageLocation(*Expr->getArg(0)));
  handleConstPointerAccessorMemberCall(Expr, RecordLoc, Result, State);
}
 
static void handleNonConstMemberCall(const CallExpr *Expr,
                                     RecordStorageLocation *RecordLoc,
                                     const MatchFinder::MatchResult &Result,
                                     LatticeTransferState &State) {
  if (RecordLoc) {
    State.Lattice.clearConstMethodReturnValues(*RecordLoc);
    State.Lattice.clearConstMethodReturnStorageLocations(*RecordLoc);
  }
  if (isStatusOrType(Expr->getType()))
    transferStatusOrReturningCall(Expr, State);
}
 
static void transferNonConstMemberCall(const CXXMemberCallExpr *Expr,
                                       const MatchFinder::MatchResult &Result,
                                       LatticeTransferState &State) {
  handleNonConstMemberCall(Expr, getImplicitObjectLocation(*Expr, State.Env),
                           Result, State);
}
 
static void
transferNonConstMemberOperatorCall(const CXXOperatorCallExpr *Expr,
                                   const MatchFinder::MatchResult &Result,
                                   LatticeTransferState &State) {
  auto *RecordLoc = cast_or_null<RecordStorageLocation>(
      State.Env.getStorageLocation(*Expr->getArg(0)));
  handleNonConstMemberCall(Expr, RecordLoc, Result, State);
}
 
static void transferMakePredicateFormatterFromIsOkMatcherCall(
    const CallExpr *Expr, const MatchFinder::MatchResult &,
    LatticeTransferState &State) {
  State.Env.setValue(
      locForOkPredicate(State.Env.getResultObjectLocation(*Expr)),
      State.Env.getBoolLiteralValue(true));
}
 
static void transferStatusIsOkMatcherCall(const CallExpr *Expr,
                                          const MatchFinder::MatchResult &,
                                          LatticeTransferState &State) {
  BoolValue &OkMatcherVal = State.Env.getBoolLiteralValue(true);
  State.Env.setValue(locForOkMatcher(State.Env.getResultObjectLocation(*Expr)),
                     OkMatcherVal);
}
 
static void transferMakePredicateFormatterFromStatusIsMatcherCall(
    const CallExpr *Expr, const MatchFinder::MatchResult &,
    LatticeTransferState &State) {
  assert(Expr->isPRValue());
  auto &Loc = State.Env.getResultObjectLocation(*Expr->getArg(0));
  auto &OkMatcherLoc = locForOkMatcher(Loc);
  BoolValue *OkMatcherVal = State.Env.get<BoolValue>(OkMatcherLoc);
  if (OkMatcherVal == nullptr)
    return;
  State.Env.setValue(
      locForOkPredicate(State.Env.getResultObjectLocation(*Expr)),
      *OkMatcherVal);
}
 
static void
transferPredicateFormatterMatcherCall(const CXXOperatorCallExpr *Expr,
                                      LatticeTransferState &State,
                                      bool IsStatusOr) {
  auto *Loc = State.Env.get<RecordStorageLocation>(*Expr->getArg(0));
  if (Loc == nullptr)
    return;
 
  auto *ObjectLoc = State.Env.get<RecordStorageLocation>(*Expr->getArg(2));
  if (ObjectLoc == nullptr)
    return;
 
  auto &OkPredicateLoc = locForOkPredicate(*Loc);
  BoolValue *OkPredicateVal = State.Env.get<BoolValue>(OkPredicateLoc);
  if (OkPredicateVal == nullptr)
    return;
 
  if (IsStatusOr)
    ObjectLoc = &locForStatus(*ObjectLoc);
  auto &StatusOk = valForOk(*ObjectLoc, State.Env);
 
  auto &A = State.Env.arena();
  auto &Res = State.Env.makeAtomicBoolValue();
  State.Env.assume(
      A.makeImplies(OkPredicateVal->formula(),
                    A.makeEquals(StatusOk.formula(), Res.formula())));
  State.Env.setValue(locForOk(State.Env.getResultObjectLocation(*Expr)), Res);
}
 
static void
transferAssertionResultConstructFromBoolCall(const CXXConstructExpr *Expr,
                                             const MatchFinder::MatchResult &,
                                             LatticeTransferState &State) {
  assert(Expr->getNumArgs() > 0);
 
  auto *StatusAdaptorLoc = State.Env.get<StorageLocation>(*Expr->getArg(0));
  if (StatusAdaptorLoc == nullptr)
    return;
  BoolValue *OkVal = State.Env.get<BoolValue>(*StatusAdaptorLoc);
  if (OkVal == nullptr)
    return;
  State.Env.setValue(locForOk(State.Env.getResultObjectLocation(*Expr)),
                     *OkVal);
}
 
static void
transferAssertionResultOperatorBoolCall(const CXXMemberCallExpr *Expr,
                                        const MatchFinder::MatchResult &,
                                        LatticeTransferState &State) {
  auto *RecordLoc = getImplicitObjectLocation(*Expr, State.Env);
  if (RecordLoc == nullptr)
    return;
  BoolValue *OkVal = State.Env.get<BoolValue>(locForOk(*RecordLoc));
  if (OkVal == nullptr)
    return;
  auto &A = State.Env.arena();
  auto &Res = State.Env.makeAtomicBoolValue();
  State.Env.assume(A.makeEquals(OkVal->formula(), Res.formula()));
  State.Env.setValue(*Expr, Res);
}
 
static void transferDerefCall(const CXXOperatorCallExpr *Expr,
                              const MatchFinder::MatchResult &,
                              LatticeTransferState &State) {
  auto *StatusOrLoc = State.Env.get<RecordStorageLocation>(*Expr->getArg(0));
 
  if (StatusOrLoc && State.Env.getStorageLocation(*Expr) == nullptr)
    State.Env.setStorageLocation(*Expr,
                                 StatusOrLoc->getSyntheticField("value"));
}
 
static void transferArrowCall(const CXXOperatorCallExpr *Expr,
                              const MatchFinder::MatchResult &,
                              LatticeTransferState &State) {
  auto *StatusOrLoc = State.Env.get<RecordStorageLocation>(*Expr->getArg(0));
  if (!StatusOrLoc)
    return;
  State.Env.setValue(*Expr, State.Env.create<PointerValue>(
                                StatusOrLoc->getSyntheticField("value")));
}
 
static void transferValueCall(const CXXMemberCallExpr *Expr,
                              const MatchFinder::MatchResult &,
                              LatticeTransferState &State) {
  auto *StatusOrLoc = getImplicitObjectLocation(*Expr, State.Env);
 
  if (StatusOrLoc && State.Env.getStorageLocation(*Expr) == nullptr)
    State.Env.setStorageLocation(*Expr,
                                 StatusOrLoc->getSyntheticField("value"));
}
 
static void transferStatusOrPtrReturningCall(const CallExpr *Expr,
                                             const MatchFinder::MatchResult &,
                                             LatticeTransferState &State) {
  PointerValue *PointerVal =
      dyn_cast_or_null<PointerValue>(State.Env.getValue(*Expr));
  if (!PointerVal) {
    PointerVal = cast<PointerValue>(State.Env.createValue(Expr->getType()));
    State.Env.setValue(*Expr, *PointerVal);
  }
 
  auto *RecordLoc =
      dyn_cast_or_null<RecordStorageLocation>(&PointerVal->getPointeeLoc());
  if (RecordLoc != nullptr &&
      State.Env.getValue(locForOk(locForStatus(*RecordLoc))) == nullptr)
    initializeStatusOr(*RecordLoc, State.Env);
}
 
static void transferStatusPtrReturningCall(const CallExpr *Expr,
                                           const MatchFinder::MatchResult &,
                                           LatticeTransferState &State) {
  PointerValue *PointerVal =
      dyn_cast_or_null<PointerValue>(State.Env.getValue(*Expr));
  if (!PointerVal) {
    PointerVal = cast<PointerValue>(State.Env.createValue(Expr->getType()));
    State.Env.setValue(*Expr, *PointerVal);
  }
 
  auto *RecordLoc =
      dyn_cast_or_null<RecordStorageLocation>(&PointerVal->getPointeeLoc());
  if (RecordLoc != nullptr &&
      State.Env.getValue(locForOk(*RecordLoc)) == nullptr)
    initializeStatus(*RecordLoc, State.Env);
}
 
static RecordStorageLocation *
getSmartPtrLikeStorageLocation(const Expr &E, const Environment &Env) {
  if (!E.isPRValue())
    return dyn_cast_or_null<RecordStorageLocation>(Env.getStorageLocation(E));
  if (auto *PointerVal = dyn_cast_or_null<PointerValue>(Env.getValue(E)))
    return dyn_cast_or_null<RecordStorageLocation>(
        &PointerVal->getPointeeLoc());
  return nullptr;
}
 
CFGMatchSwitch<LatticeTransferState>
buildTransferMatchSwitch(ASTContext &Ctx,
                         CFGMatchSwitchBuilder<LatticeTransferState> Builder) {
  using namespace ::clang::ast_matchers;
  return std::move(Builder)
      .CaseOfCFGStmt<CallExpr>(
          isMakePredicateFormatterFromIsOkMatcherCall(),
          transferMakePredicateFormatterFromIsOkMatcherCall)
      .CaseOfCFGStmt<CallExpr>(isStatusIsOkMatcherCall(),
                               transferStatusIsOkMatcherCall)
      .CaseOfCFGStmt<CallExpr>(
          isMakePredicateFormatterFromStatusIsMatcherCall(),
          transferMakePredicateFormatterFromStatusIsMatcherCall)
      .CaseOfCFGStmt<CXXOperatorCallExpr>(
          isPredicateFormatterFromStatusOrMatcherCall(),
          [](const CXXOperatorCallExpr *Expr, const MatchFinder::MatchResult &,
             LatticeTransferState &State) {
            transferPredicateFormatterMatcherCall(Expr, State,
                                                  /*IsStatusOr=*/true);
          })
      .CaseOfCFGStmt<CXXOperatorCallExpr>(
          isPredicateFormatterFromStatusMatcherCall(),
          [](const CXXOperatorCallExpr *Expr, const MatchFinder::MatchResult &,
             LatticeTransferState &State) {
            transferPredicateFormatterMatcherCall(Expr, State,
                                                  /*IsStatusOr=*/false);
          })
      .CaseOfCFGStmt<CXXConstructExpr>(
          isAssertionResultConstructFromBoolCall(),
          transferAssertionResultConstructFromBoolCall)
      .CaseOfCFGStmt<CXXMemberCallExpr>(isAssertionResultOperatorBoolCall(),
                                        transferAssertionResultOperatorBoolCall)
      .CaseOfCFGStmt<CXXMemberCallExpr>(isStatusOrMemberCallWithName("ok"),
                                        transferStatusOrOkCall)
      .CaseOfCFGStmt<CXXMemberCallExpr>(isStatusOrMemberCallWithName("status"),
                                        transferStatusCall)
      .CaseOfCFGStmt<CXXMemberCallExpr>(isStatusMemberCallWithName("ok"),
                                        transferStatusOkCall)
      .CaseOfCFGStmt<CXXMemberCallExpr>(isStatusMemberCallWithName("Update"),
                                        transferStatusUpdateCall)
      .CaseOfCFGStmt<CXXOperatorCallExpr>(
          isComparisonOperatorCall("=="),
          [](const CXXOperatorCallExpr *Expr, const MatchFinder::MatchResult &,
             LatticeTransferState &State) {
            transferComparisonOperator(Expr, State,
                                       /*IsNegative=*/false);
          })
      .CaseOfCFGStmt<CXXOperatorCallExpr>(
          isComparisonOperatorCall("!="),
          [](const CXXOperatorCallExpr *Expr, const MatchFinder::MatchResult &,
             LatticeTransferState &State) {
            transferComparisonOperator(Expr, State,
                                       /*IsNegative=*/true);
          })
      .CaseOfCFGStmt<BinaryOperator>(
          isPointerComparisonOperatorCall("=="),
          [](const BinaryOperator *Expr, const MatchFinder::MatchResult &,
             LatticeTransferState &State) {
            transferPointerComparisonOperator(Expr, State,
                                              /*IsNegative=*/false);
          })
      .CaseOfCFGStmt<BinaryOperator>(
          isPointerComparisonOperatorCall("!="),
          [](const BinaryOperator *Expr, const MatchFinder::MatchResult &,
             LatticeTransferState &State) {
            transferPointerComparisonOperator(Expr, State,
                                              /*IsNegative=*/true);
          })
      .CaseOfCFGStmt<CallExpr>(isOkStatusCall(), transferOkStatusCall)
      .CaseOfCFGStmt<CallExpr>(isNotOkStatusCall(), transferNotOkStatusCall)
      .CaseOfCFGStmt<CXXMemberCallExpr>(isStatusOrMemberCallWithName("emplace"),
                                        transferEmplaceCall)
      .CaseOfCFGStmt<CXXOperatorCallExpr>(isStatusOrValueAssignmentCall(),
                                          transferValueAssignmentCall)
      .CaseOfCFGStmt<CXXConstructExpr>(isStatusOrValueConstructor(),
                                       transferValueConstructor)
      .CaseOfCFGStmt<CXXOperatorCallExpr>(isStatusOrOperatorCallWithName("->"),
                                          transferArrowCall)
      .CaseOfCFGStmt<CXXOperatorCallExpr>(isStatusOrOperatorCallWithName("*"),
                                          transferDerefCall)
      .CaseOfCFGStmt<CXXMemberCallExpr>(isStatusOrMemberCallWithName("value"),
                                        transferValueCall)
      .CaseOfCFGStmt<CallExpr>(isAsStatusCallWithStatus(),
                               transferAsStatusCallWithStatus)
      .CaseOfCFGStmt<CallExpr>(isAsStatusCallWithStatusOr(),
                               transferAsStatusCallWithStatusOr)
      .CaseOfCFGStmt<CallExpr>(isLoggingGetReferenceableValueCall(),
                               transferLoggingGetReferenceableValueCall)
      .CaseOfCFGStmt<CallExpr>(isLoggingCheckEqImpl(),
                               transferLoggingCheckEqImpl)
      // This needs to go before the const accessor call matcher, because these
      // look like them, but we model `operator`* and `get` to return the same
      // object. Also, we model them for non-const cases.
      .CaseOfCFGStmt<CXXOperatorCallExpr>(
          isPointerLikeOperatorStar(),
          [](const CXXOperatorCallExpr *E,
             const MatchFinder::MatchResult &Result,
             LatticeTransferState &State) {
            transferSmartPointerLikeCachedDeref(
                E, getSmartPtrLikeStorageLocation(*E->getArg(0), State.Env),
                State, [](StorageLocation &Loc) {});
          })
      .CaseOfCFGStmt<CXXOperatorCallExpr>(
          isPointerLikeOperatorArrow(),
          [](const CXXOperatorCallExpr *E,
             const MatchFinder::MatchResult &Result,
             LatticeTransferState &State) {
            transferSmartPointerLikeCachedGet(
                E, getSmartPtrLikeStorageLocation(*E->getArg(0), State.Env),
                State, [](StorageLocation &Loc) {});
          })
      .CaseOfCFGStmt<CXXMemberCallExpr>(
          isSmartPointerLikeValueMethodCall(),
          [](const CXXMemberCallExpr *E, const MatchFinder::MatchResult &Result,
             LatticeTransferState &State) {
            transferSmartPointerLikeCachedDeref(
                E, getImplicitObjectLocation(*E, State.Env), State,
                [](StorageLocation &Loc) {});
          })
      .CaseOfCFGStmt<CXXMemberCallExpr>(
          isSmartPointerLikeGetMethodCall(),
          [](const CXXMemberCallExpr *E, const MatchFinder::MatchResult &Result,
             LatticeTransferState &State) {
            transferSmartPointerLikeCachedGet(
                E, getImplicitObjectLocation(*E, State.Env), State,
                [](StorageLocation &Loc) {});
          })
      // const accessor calls
      .CaseOfCFGStmt<CXXMemberCallExpr>(isConstAccessorMemberCall(),
                                        transferConstAccessorMemberCall)
      .CaseOfCFGStmt<CXXOperatorCallExpr>(
          isConstAccessorMemberOperatorCall(),
          transferConstAccessorMemberOperatorCall)
      .CaseOfCFGStmt<CXXMemberCallExpr>(isConstPointerAccessorMemberCall(),
                                        transferConstPointerAccessorMemberCall)
      .CaseOfCFGStmt<CXXOperatorCallExpr>(
          isConstPointerAccessorMemberOperatorCall(),
          transferConstPointerAccessorMemberOperatorCall)
      // non-const member calls that may modify the state of an object.
      .CaseOfCFGStmt<CXXMemberCallExpr>(isNonConstMemberCall(),
                                        transferNonConstMemberCall)
      .CaseOfCFGStmt<CXXOperatorCallExpr>(isNonConstMemberOperatorCall(),
                                          transferNonConstMemberOperatorCall)
      // N.B. this has to be after transferConstMemberCall, otherwise we would
      // always return a fresh RecordStorageLocation for the StatusOr.
      .CaseOfCFGStmt<CallExpr>(isStatusOrReturningCall(),
                               [](const CallExpr *Expr,
                                  const MatchFinder::MatchResult &,
                                  LatticeTransferState &State) {
                                 transferStatusOrReturningCall(Expr, State);
                               })
      .CaseOfCFGStmt<CallExpr>(isStatusOrPtrReturningCall(),
                               transferStatusOrPtrReturningCall)
      .CaseOfCFGStmt<CallExpr>(isStatusPtrReturningCall(),
                               transferStatusPtrReturningCall)
      // N.B. These need to come after all other CXXConstructExpr.
      // These are there to make sure that every Status and StatusOr object
      // have their ok boolean initialized when constructed. If we were to
      // lazily initialize them when we first access them, we can produce
      // false positives if that first access is in a control flow statement.
      // You can comment out these two constructors and see tests fail.
      .CaseOfCFGStmt<CXXConstructExpr>(isStatusOrConstructor(),
                                       transferStatusOrConstructor)
      .CaseOfCFGStmt<CXXConstructExpr>(isStatusConstructor(),
                                       transferStatusConstructor)
      .CaseOfCFGStmt<ImplicitCastExpr>(
          implicitCastExpr(hasCastKind(CK_PointerToBoolean)),
          transferPointerToBoolean)
      .Build();
}
 
QualType findStatusType(const ASTContext &Ctx) {
  for (Type *Ty : Ctx.getTypes())
    if (isStatusType(QualType(Ty, 0)))
      return QualType(Ty, 0);
 
  return QualType();
}
 
UncheckedStatusOrAccessModel::UncheckedStatusOrAccessModel(ASTContext &Ctx,
                                                           Environment &Env)
    : DataflowAnalysis<UncheckedStatusOrAccessModel,
                       UncheckedStatusOrAccessModel::Lattice>(Ctx),
      TransferMatchSwitch(buildTransferMatchSwitch(Ctx, {})) {
  QualType StatusType = findStatusType(Ctx);
  Env.getDataflowAnalysisContext().setSyntheticFieldCallback(
      [StatusType](QualType Ty) -> llvm::StringMap<QualType> {
        CXXRecordDecl *RD = Ty->getAsCXXRecordDecl();
        if (RD == nullptr)
          return {};
 
        if (auto Fields = getSyntheticFields(Ty, StatusType, *RD);
            !Fields.empty())
          return Fields;
        return {};
      });
}
 
void UncheckedStatusOrAccessModel::transfer(const CFGElement &Elt, Lattice &L,
                                            Environment &Env) {
  LatticeTransferState State(L, Env);
  TransferMatchSwitch(Elt, getASTContext(), State);
}
 
} // namespace clang::dataflow::statusor_model