/usr/src/gnu/usr.bin/clang/liblldbPluginExpressionParser/../../../llvm/lldb/source/Plugins/ExpressionParser/Clang/CxxModuleHandler.cpp

Bug Summary

File:	src/gnu/usr.bin/clang/liblldbPluginExpressionParser/../../../llvm/lldb/source/Plugins/ExpressionParser/Clang/CxxModuleHandler.cpp
Warning:	line 142, column 31 Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -cc1 -triple amd64-unknown-openbsd7.0 -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name CxxModuleHandler.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -mrelocation-model static -mframe-pointer=all -relaxed-aliasing -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/usr/src/gnu/usr.bin/clang/liblldbPluginExpressionParser/obj -resource-dir /usr/local/lib/clang/13.0.0 -I /usr/src/gnu/usr.bin/clang/liblldbPluginExpressionParser/../../../llvm/llvm/include -I /usr/src/gnu/usr.bin/clang/liblldbPluginExpressionParser/../include -I /usr/src/gnu/usr.bin/clang/liblldbPluginExpressionParser/obj -I /usr/src/gnu/usr.bin/clang/liblldbPluginExpressionParser/obj/../include -D NDEBUG -D __STDC_LIMIT_MACROS -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D LLVM_PREFIX="/usr" -I /usr/src/gnu/usr.bin/clang/liblldbPluginExpressionParser/../../../llvm/lldb/include -I /usr/src/gnu/usr.bin/clang/liblldbPluginExpressionParser/../../../llvm/lldb/source -I /usr/src/gnu/usr.bin/clang/liblldbPluginExpressionParser/../../../llvm/clang/include -internal-isystem /usr/include/c++/v1 -internal-isystem /usr/local/lib/clang/13.0.0/include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/usr/src/gnu/usr.bin/clang/liblldbPluginExpressionParser/obj -ferror-limit 19 -fvisibility-inlines-hidden -fwrapv -stack-protector 2 -fno-rtti -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -fno-builtin-malloc -fno-builtin-calloc -fno-builtin-realloc -fno-builtin-valloc -fno-builtin-free -fno-builtin-strdup -fno-builtin-strndup -analyzer-output=html -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /home/ben/Projects/vmm/scan-build/2022-01-12-194120-40624-1 -x c++ /usr/src/gnu/usr.bin/clang/liblldbPluginExpressionParser/../../../llvm/lldb/source/Plugins/ExpressionParser/Clang/CxxModuleHandler.cpp

/usr/src/gnu/usr.bin/clang/liblldbPluginExpressionParser/../../../llvm/lldb/source/Plugins/ExpressionParser/Clang/CxxModuleHandler.cpp

→

1//===-- CxxModuleHandler.cpp ----------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8 
9#include "Plugins/ExpressionParser/Clang/CxxModuleHandler.h"
10#include "Plugins/TypeSystem/Clang/TypeSystemClang.h"
11 
12#include "lldb/Utility/Log.h"
13#include "clang/Sema/Lookup.h"
14#include "llvm/Support/Error.h"
15 
16using namespace lldb_private;
17using namespace clang;
18 
19CxxModuleHandler::CxxModuleHandler(ASTImporter &importer, ASTContext *target)
20    : m_importer(&importer),
21      m_sema(TypeSystemClang::GetASTContext(target)->getSema()) {
22 
23  std::initializer_list<const char *> supported_names = {
24      // containers
25      "array",
26      "deque",
27      "forward_list",
28      "list",
29      "queue",
30      "stack",
31      "vector",
32      // pointers
33      "shared_ptr",
34      "unique_ptr",
35      "weak_ptr",
36      // iterator
37      "move_iterator",
38      "__wrap_iter",
39      // utility
40      "allocator",
41      "pair",
42  };
43  m_supported_templates.insert(supported_names.begin(), supported_names.end());
44}
45 
46/// Builds a list of scopes that point into the given context.
47///
48/// \param sema The sema that will be using the scopes.
49/// \param ctxt The context that the scope should look into.
50/// \param result A list of scopes. The scopes need to be freed by the caller
51///               (except the TUScope which is owned by the sema).
52static void makeScopes(Sema &sema, DeclContext *ctxt,
53                       std::vector<Scope *> &result) {
54  // FIXME: The result should be a list of unique_ptrs, but the TUScope makes
55  // this currently impossible as it's owned by the Sema.
56 
57  if (auto parent = ctxt->getParent()) {
58    makeScopes(sema, parent, result);
59 
60    Scope *scope =
61        new Scope(result.back(), Scope::DeclScope, sema.getDiagnostics());
62    scope->setEntity(ctxt);
63    result.push_back(scope);
64  } else
65    result.push_back(sema.TUScope);
66}
67 
68/// Uses the Sema to look up the given name in the given DeclContext.
69static std::unique_ptr<LookupResult>
70emulateLookupInCtxt(Sema &sema, llvm::StringRef name, DeclContext *ctxt) {
71  IdentifierInfo &ident = sema.getASTContext().Idents.get(name);
72 
73  std::unique_ptr<LookupResult> lookup_result;
74  lookup_result = std::make_unique<LookupResult>(sema, DeclarationName(&ident),
75                                                 SourceLocation(),
76                                                 Sema::LookupOrdinaryName);
77 
78  // Usually during parsing we already encountered the scopes we would use. But
79  // here don't have these scopes so we have to emulate the behavior of the
80  // Sema during parsing.
81  std::vector<Scope *> scopes;
82  makeScopes(sema, ctxt, scopes);
83 
84  // Now actually perform the lookup with the sema.
85  sema.LookupName(*lookup_result, scopes.back());
86 
87  // Delete all the allocated scopes beside the translation unit scope (which
88  // has depth 0).
89  for (Scope *s : scopes)
90    if (s->getDepth() != 0)
91      delete s;
92 
93  return lookup_result;
94}
95 
96/// Error class for handling problems when finding a certain DeclContext.
97struct MissingDeclContext : public llvm::ErrorInfo<MissingDeclContext> {
98 
99  static char ID;
100 
101  MissingDeclContext(DeclContext *context, std::string error)
102      : m_context(context), m_error(error) {}
103 
104  DeclContext *m_context;
105  std::string m_error;
106 
107  void log(llvm::raw_ostream &OS) const override {
108    OS << llvm::formatv("error when reconstructing context of kind {0}:{1}",
109                        m_context->getDeclKindName(), m_error);
110  }
111 
112  std::error_code convertToErrorCode() const override {
113    return llvm::inconvertibleErrorCode();
114  }
115};
116 
117char MissingDeclContext::ID = 0;
118 
119/// Given a foreign decl context, this function finds the equivalent local
120/// decl context in the ASTContext of the given Sema. Potentially deserializes
121/// decls from the 'std' module if necessary.
122static llvm::Expected<DeclContext *>
123getEqualLocalDeclContext(Sema &sema, DeclContext *foreign_ctxt) {
124 
125  // Inline namespaces don't matter for lookups, so let's skip them.
126  while (foreign_ctxt && foreign_ctxt->isInlineNamespace())
11
←
Assuming 'foreign_ctxt' is non-null→
12
←
Loop condition is false. Execution continues on line 130→
15
←
Assuming 'foreign_ctxt' is non-null→
16
←
Loop condition is false. Execution continues on line 130→
19
←
Assuming 'foreign_ctxt' is non-null→
20
←
Loop condition is false. Execution continues on line 130→
127    foreign_ctxt = foreign_ctxt->getParent();
128 
129  // If the foreign context is the TU, we just return the local TU.
130  if (foreign_ctxt->isTranslationUnit())
13
←
Taking false branch→
17
←
Taking false branch→
21
←
Calling 'DeclContext::isTranslationUnit'→
24
←
Returning from 'DeclContext::isTranslationUnit'→
25
←
Taking false branch→
131    return sema.getASTContext().getTranslationUnitDecl();
132 
133  // Recursively find/build the parent DeclContext.
134  llvm::Expected<DeclContext *> parent =
135      getEqualLocalDeclContext(sema, foreign_ctxt->getParent());
14
←
Calling 'getEqualLocalDeclContext'→
18
←
Calling 'getEqualLocalDeclContext'→
136  if (!parent)
26
←
Calling 'Expected::operator bool'→
29
←
Returning from 'Expected::operator bool'→
30
←
Taking false branch→
137    return parent;
138 
139  // We currently only support building namespaces.
140  if (foreign_ctxt->isNamespace()) {
31
←
Calling 'DeclContext::isNamespace'→
34
←
Returning from 'DeclContext::isNamespace'→
35
←
Taking true branch→
141    NamedDecl *ns = llvm::dyn_cast<NamedDecl>(foreign_ctxt);
36
←
Assuming 'foreign_ctxt' is not a 'NamedDecl'→
37
←
'ns' initialized to a null pointer value→
142    llvm::StringRef ns_name = ns->getName();
38
←
Called C++ object pointer is null
143 
144    auto lookup_result = emulateLookupInCtxt(sema, ns_name, *parent);
145    for (NamedDecl *named_decl : *lookup_result) {
146      if (DeclContext *DC = llvm::dyn_cast<DeclContext>(named_decl))
147        return DC->getPrimaryContext();
148    }
149    return llvm::make_error<MissingDeclContext>(
150        foreign_ctxt,
151        "Couldn't find namespace " + ns->getQualifiedNameAsString());
152  }
153 
154  return llvm::make_error<MissingDeclContext>(foreign_ctxt, "Unknown context ");
155}
156 
157/// Returns true iff tryInstantiateStdTemplate supports instantiating a template
158/// with the given template arguments.
159static bool templateArgsAreSupported(ArrayRef<TemplateArgument> a) {
160  for (const TemplateArgument &arg : a) {
161    switch (arg.getKind()) {
162    case TemplateArgument::Type:
163    case TemplateArgument::Integral:
164      break;
165    default:
166      // TemplateArgument kind hasn't been handled yet.
167      return false;
168    }
169  }
170  return true;
171}
172 
173/// Constructor function for Clang declarations. Ensures that the created
174/// declaration is registered with the ASTImporter.
175template <typename T, typename... Args>
176T *createDecl(ASTImporter &importer, Decl *from_d, Args &&... args) {
177  T *to_d = T::Create(std::forward<Args>(args)...);
178  importer.RegisterImportedDecl(from_d, to_d);
179  return to_d;
180}
181 
182llvm::Optional<Decl *> CxxModuleHandler::tryInstantiateStdTemplate(Decl *d) {
183  Log *log = lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_EXPRESSIONS(1u << 8));
184 
185  // If we don't have a template to instiantiate, then there is nothing to do.
186  auto td = dyn_cast<ClassTemplateSpecializationDecl>(d);
3
←
Assuming 'd' is a 'ClassTemplateSpecializationDecl'→
187  if (!td3.1
'td' is non-null
3.1
'td' is non-null
3.1
'td' is non-null
)
4
←
Taking false branch→
188    return llvm::None;
189 
190  // We only care about templates in the std namespace.
191  if (!td->getDeclContext()->isStdNamespace())
5
←
Assuming the condition is false→
6
←
Taking false branch→
192    return llvm::None;
193 
194  // We have a list of supported template names.
195  if (!m_supported_templates.contains(td->getName()))
7
←
Assuming the condition is false→
8
←
Taking false branch→
196    return llvm::None;
197 
198  // Early check if we even support instantiating this template. We do this
199  // before we import anything into the target AST.
200  auto &foreign_args = td->getTemplateInstantiationArgs();
201  if (!templateArgsAreSupported(foreign_args.asArray()))
9
←
Taking false branch→
202    return llvm::None;
203 
204  // Find the local DeclContext that corresponds to the DeclContext of our
205  // decl we want to import.
206  llvm::Expected<DeclContext *> to_context =
207      getEqualLocalDeclContext(*m_sema, td->getDeclContext());
10
←
Calling 'getEqualLocalDeclContext'→
208  if (!to_context) {
209    LLDB_LOG_ERROR(log, to_context.takeError(),do { ::lldb_private::Log *log_private = (log); ::llvm::Error error_private
 = (to_context.takeError()); if (log_private && error_private
) { log_private->FormatError(::std::move(error_private), "/usr/src/gnu/usr.bin/clang/liblldbPluginExpressionParser/../../../llvm/lldb/source/Plugins/ExpressionParser/Clang/CxxModuleHandler.cpp"
, __func__, "Got error while searching equal local DeclContext for decl "
 "'{1}':\n{0}", td->getName()); } else ::llvm::consumeError
(::std::move(error_private)); } while (0)
210                   "Got error while searching equal local DeclContext for decl "do { ::lldb_private::Log *log_private = (log); ::llvm::Error error_private
 = (to_context.takeError()); if (log_private && error_private
) { log_private->FormatError(::std::move(error_private), "/usr/src/gnu/usr.bin/clang/liblldbPluginExpressionParser/../../../llvm/lldb/source/Plugins/ExpressionParser/Clang/CxxModuleHandler.cpp"
, __func__, "Got error while searching equal local DeclContext for decl "
 "'{1}':\n{0}", td->getName()); } else ::llvm::consumeError
(::std::move(error_private)); } while (0)
211                   "'{1}':\n{0}",do { ::lldb_private::Log *log_private = (log); ::llvm::Error error_private
 = (to_context.takeError()); if (log_private && error_private
) { log_private->FormatError(::std::move(error_private), "/usr/src/gnu/usr.bin/clang/liblldbPluginExpressionParser/../../../llvm/lldb/source/Plugins/ExpressionParser/Clang/CxxModuleHandler.cpp"
, __func__, "Got error while searching equal local DeclContext for decl "
 "'{1}':\n{0}", td->getName()); } else ::llvm::consumeError
(::std::move(error_private)); } while (0)
212                   td->getName())do { ::lldb_private::Log *log_private = (log); ::llvm::Error error_private
 = (to_context.takeError()); if (log_private && error_private
) { log_private->FormatError(::std::move(error_private), "/usr/src/gnu/usr.bin/clang/liblldbPluginExpressionParser/../../../llvm/lldb/source/Plugins/ExpressionParser/Clang/CxxModuleHandler.cpp"
, __func__, "Got error while searching equal local DeclContext for decl "
 "'{1}':\n{0}", td->getName()); } else ::llvm::consumeError
(::std::move(error_private)); } while (0);
213    return llvm::None;
214  }
215 
216  // Look up the template in our local context.
217  std::unique_ptr<LookupResult> lookup =
218      emulateLookupInCtxt(*m_sema, td->getName(), *to_context);
219 
220  ClassTemplateDecl *new_class_template = nullptr;
221  for (auto LD : *lookup) {
222    if ((new_class_template = dyn_cast<ClassTemplateDecl>(LD)))
223      break;
224  }
225  if (!new_class_template)
226    return llvm::None;
227 
228  // Import the foreign template arguments.
229  llvm::SmallVector<TemplateArgument, 4> imported_args;
230 
231  // If this logic is changed, also update templateArgsAreSupported.
232  for (const TemplateArgument &arg : foreign_args.asArray()) {
233    switch (arg.getKind()) {
234    case TemplateArgument::Type: {
235      llvm::Expected<QualType> type = m_importer->Import(arg.getAsType());
236      if (!type) {
237        LLDB_LOG_ERROR(log, type.takeError(), "Couldn't import type: {0}")do { ::lldb_private::Log *log_private = (log); ::llvm::Error error_private
 = (type.takeError()); if (log_private && error_private
) { log_private->FormatError(::std::move(error_private), "/usr/src/gnu/usr.bin/clang/liblldbPluginExpressionParser/../../../llvm/lldb/source/Plugins/ExpressionParser/Clang/CxxModuleHandler.cpp"
, __func__, "Couldn't import type: {0}"); } else ::llvm::consumeError
(::std::move(error_private)); } while (0);
238        return llvm::None;
239      }
240      imported_args.push_back(TemplateArgument(*type));
241      break;
242    }
243    case TemplateArgument::Integral: {
244      llvm::APSInt integral = arg.getAsIntegral();
245      llvm::Expected<QualType> type =
246          m_importer->Import(arg.getIntegralType());
247      if (!type) {
248        LLDB_LOG_ERROR(log, type.takeError(), "Couldn't import type: {0}")do { ::lldb_private::Log *log_private = (log); ::llvm::Error error_private
 = (type.takeError()); if (log_private && error_private
) { log_private->FormatError(::std::move(error_private), "/usr/src/gnu/usr.bin/clang/liblldbPluginExpressionParser/../../../llvm/lldb/source/Plugins/ExpressionParser/Clang/CxxModuleHandler.cpp"
, __func__, "Couldn't import type: {0}"); } else ::llvm::consumeError
(::std::move(error_private)); } while (0);
249        return llvm::None;
250      }
251      imported_args.push_back(
252          TemplateArgument(d->getASTContext(), integral, *type));
253      break;
254    }
255    default:
256      assert(false && "templateArgsAreSupported not updated?")((void)0);
257    }
258  }
259 
260  // Find the class template specialization declaration that
261  // corresponds to these arguments.
262  void *InsertPos = nullptr;
263  ClassTemplateSpecializationDecl *result =
264      new_class_template->findSpecialization(imported_args, InsertPos);
265 
266  if (result) {
267    // We found an existing specialization in the module that fits our arguments
268    // so we can treat it as the result and register it with the ASTImporter.
269    m_importer->RegisterImportedDecl(d, result);
270    return result;
271  }
272 
273  // Instantiate the template.
274  result = createDecl<ClassTemplateSpecializationDecl>(
275      *m_importer, d, m_sema->getASTContext(),
276      new_class_template->getTemplatedDecl()->getTagKind(),
277      new_class_template->getDeclContext(),
278      new_class_template->getTemplatedDecl()->getLocation(),
279      new_class_template->getLocation(), new_class_template, imported_args,
280      nullptr);
281 
282  new_class_template->AddSpecialization(result, InsertPos);
283  if (new_class_template->isOutOfLine())
284    result->setLexicalDeclContext(
285        new_class_template->getLexicalDeclContext());
286  return result;
287}
288 
289llvm::Optional<Decl *> CxxModuleHandler::Import(Decl *d) {
290  if (!isValid())
1
Taking false branch→
291    return {};
292 
293  return tryInstantiateStdTemplate(d);
2
←
Calling 'CxxModuleHandler::tryInstantiateStdTemplate'→
294}

←

/usr/src/gnu/usr.bin/clang/liblldbPluginExpressionParser/../../../llvm/clang/include/clang/AST/DeclBase.h

→

1//===- DeclBase.h - Base Classes for representing declarations --*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9//  This file defines the Decl and DeclContext interfaces.
10//
11//===----------------------------------------------------------------------===//

13#ifndef LLVM_CLANG_AST_DECLBASE_H
14#define LLVM_CLANG_AST_DECLBASE_H

16#include "clang/AST/ASTDumperUtils.h"
17#include "clang/AST/AttrIterator.h"
18#include "clang/AST/DeclarationName.h"
19#include "clang/Basic/IdentifierTable.h"
20#include "clang/Basic/LLVM.h"
21#include "clang/Basic/SourceLocation.h"
22#include "clang/Basic/Specifiers.h"
23#include "llvm/ADT/ArrayRef.h"
24#include "llvm/ADT/PointerIntPair.h"
25#include "llvm/ADT/PointerUnion.h"
26#include "llvm/ADT/iterator.h"
27#include "llvm/ADT/iterator_range.h"
28#include "llvm/Support/Casting.h"
29#include "llvm/Support/Compiler.h"
30#include "llvm/Support/PrettyStackTrace.h"
31#include "llvm/Support/VersionTuple.h"
32#include <algorithm>
33#include <cassert>
34#include <cstddef>
35#include <iterator>
36#include <string>
37#include <type_traits>
38#include <utility>

40namespace clang {

42class ASTContext;
43class ASTMutationListener;
44class Attr;
45class BlockDecl;
46class DeclContext;
47class ExternalSourceSymbolAttr;
48class FunctionDecl;
49class FunctionType;
50class IdentifierInfo;
51enum Linkage : unsigned char;
52class LinkageSpecDecl;
53class Module;
54class NamedDecl;
55class ObjCCategoryDecl;
56class ObjCCategoryImplDecl;
57class ObjCContainerDecl;
58class ObjCImplDecl;
59class ObjCImplementationDecl;
60class ObjCInterfaceDecl;
61class ObjCMethodDecl;
62class ObjCProtocolDecl;
63struct PrintingPolicy;
64class RecordDecl;
65class SourceManager;
66class Stmt;
67class StoredDeclsMap;
68class TemplateDecl;
69class TemplateParameterList;
70class TranslationUnitDecl;
71class UsingDirectiveDecl;

73/// Captures the result of checking the availability of a
74/// declaration.
75enum AvailabilityResult {
AR_Available = 0,
AR_NotYetIntroduced,
AR_Deprecated,
AR_Unavailable
80};

82/// Decl - This represents one declaration (or definition), e.g. a variable,
83/// typedef, function, struct, etc.
84///
85/// Note: There are objects tacked on before the *beginning* of Decl
86/// (and its subclasses) in its Decl::operator new(). Proper alignment
87/// of all subclasses (not requiring more than the alignment of Decl) is
88/// asserted in DeclBase.cpp.
89class alignas(8) Decl {
90public:
/// Lists the kind of concrete classes of Decl.
enum Kind {
93#define DECL(DERIVED, BASE) DERIVED,
94#define ABSTRACT_DECL(DECL)
95#define DECL_RANGE(BASE, START, END) \
      first##BASE = START, last##BASE = END,
97#define LAST_DECL_RANGE(BASE, START, END) \
      first##BASE = START, last##BASE = END
99#include "clang/AST/DeclNodes.inc"
};

/// A placeholder type used to construct an empty shell of a
/// decl-derived type that will be filled in later (e.g., by some
/// deserialization method).
struct EmptyShell {};

/// IdentifierNamespace - The different namespaces in which
/// declarations may appear.  According to C99 6.2.3, there are
/// four namespaces, labels, tags, members and ordinary
/// identifiers.  C++ describes lookup completely differently:
/// certain lookups merely "ignore" certain kinds of declarations,
/// usually based on whether the declaration is of a type, etc.
///
/// These are meant as bitmasks, so that searches in
/// C++ can look into the "tag" namespace during ordinary lookup.
///
/// Decl currently provides 15 bits of IDNS bits.
enum IdentifierNamespace {
  /// Labels, declared with 'x:' and referenced with 'goto x'.
  IDNS_Label               = 0x0001,

  /// Tags, declared with 'struct foo;' and referenced with
  /// 'struct foo'.  All tags are also types.  This is what
  /// elaborated-type-specifiers look for in C.
  /// This also contains names that conflict with tags in the
  /// same scope but that are otherwise ordinary names (non-type
  /// template parameters and indirect field declarations).
  IDNS_Tag                 = 0x0002,

  /// Types, declared with 'struct foo', typedefs, etc.
  /// This is what elaborated-type-specifiers look for in C++,
  /// but note that it's ill-formed to find a non-tag.
  IDNS_Type                = 0x0004,

  /// Members, declared with object declarations within tag
  /// definitions.  In C, these can only be found by "qualified"
  /// lookup in member expressions.  In C++, they're found by
  /// normal lookup.
  IDNS_Member              = 0x0008,

  /// Namespaces, declared with 'namespace foo {}'.
  /// Lookup for nested-name-specifiers find these.
  IDNS_Namespace           = 0x0010,

  /// Ordinary names.  In C, everything that's not a label, tag,
  /// member, or function-local extern ends up here.
  IDNS_Ordinary            = 0x0020,

  /// Objective C \@protocol.
  IDNS_ObjCProtocol        = 0x0040,

  /// This declaration is a friend function.  A friend function
  /// declaration is always in this namespace but may also be in
  /// IDNS_Ordinary if it was previously declared.
  IDNS_OrdinaryFriend      = 0x0080,

  /// This declaration is a friend class.  A friend class
  /// declaration is always in this namespace but may also be in
  /// IDNS_Tag|IDNS_Type if it was previously declared.
  IDNS_TagFriend           = 0x0100,

  /// This declaration is a using declaration.  A using declaration
  /// *introduces* a number of other declarations into the current
  /// scope, and those declarations use the IDNS of their targets,
  /// but the actual using declarations go in this namespace.
  IDNS_Using               = 0x0200,

  /// This declaration is a C++ operator declared in a non-class
  /// context.  All such operators are also in IDNS_Ordinary.
  /// C++ lexical operator lookup looks for these.
  IDNS_NonMemberOperator   = 0x0400,

  /// This declaration is a function-local extern declaration of a
  /// variable or function. This may also be IDNS_Ordinary if it
  /// has been declared outside any function. These act mostly like
  /// invisible friend declarations, but are also visible to unqualified
  /// lookup within the scope of the declaring function.
  IDNS_LocalExtern         = 0x0800,

  /// This declaration is an OpenMP user defined reduction construction.
  IDNS_OMPReduction        = 0x1000,

  /// This declaration is an OpenMP user defined mapper.
  IDNS_OMPMapper           = 0x2000,
};

/// ObjCDeclQualifier - 'Qualifiers' written next to the return and
/// parameter types in method declarations.  Other than remembering
/// them and mangling them into the method's signature string, these
/// are ignored by the compiler; they are consumed by certain
/// remote-messaging frameworks.
///
/// in, inout, and out are mutually exclusive and apply only to
/// method parameters.  bycopy and byref are mutually exclusive and
/// apply only to method parameters (?).  oneway applies only to
/// results.  All of these expect their corresponding parameter to
/// have a particular type.  None of this is currently enforced by
/// clang.
///
/// This should be kept in sync with ObjCDeclSpec::ObjCDeclQualifier.
enum ObjCDeclQualifier {
  OBJC_TQ_None = 0x0,
  OBJC_TQ_In = 0x1,
  OBJC_TQ_Inout = 0x2,
  OBJC_TQ_Out = 0x4,
  OBJC_TQ_Bycopy = 0x8,
  OBJC_TQ_Byref = 0x10,
  OBJC_TQ_Oneway = 0x20,

  /// The nullability qualifier is set when the nullability of the
  /// result or parameter was expressed via a context-sensitive
  /// keyword.
  OBJC_TQ_CSNullability = 0x40
};

/// The kind of ownership a declaration has, for visibility purposes.
/// This enumeration is designed such that higher values represent higher
/// levels of name hiding.
enum class ModuleOwnershipKind : unsigned {
  /// This declaration is not owned by a module.
  Unowned,

  /// This declaration has an owning module, but is globally visible
  /// (typically because its owning module is visible and we know that
  /// modules cannot later become hidden in this compilation).
  /// After serialization and deserialization, this will be converted
  /// to VisibleWhenImported.
  Visible,

  /// This declaration has an owning module, and is visible when that
  /// module is imported.
  VisibleWhenImported,

  /// This declaration has an owning module, but is only visible to
  /// lookups that occur within that module.
  ModulePrivate
};

239protected:
/// The next declaration within the same lexical
/// DeclContext. These pointers form the linked list that is
/// traversed via DeclContext's decls_begin()/decls_end().
///
/// The extra two bits are used for the ModuleOwnershipKind.
llvm::PointerIntPair<Decl *, 2, ModuleOwnershipKind> NextInContextAndBits;

247private:
friend class DeclContext;

struct MultipleDC {
  DeclContext *SemanticDC;
  DeclContext *LexicalDC;
};

/// DeclCtx - Holds either a DeclContext* or a MultipleDC*.
/// For declarations that don't contain C++ scope specifiers, it contains
/// the DeclContext where the Decl was declared.
/// For declarations with C++ scope specifiers, it contains a MultipleDC*
/// with the context where it semantically belongs (SemanticDC) and the
/// context where it was lexically declared (LexicalDC).
/// e.g.:
///
///   namespace A {
///      void f(); // SemanticDC == LexicalDC == 'namespace A'
///   }
///   void A::f(); // SemanticDC == namespace 'A'
///                // LexicalDC == global namespace
llvm::PointerUnion<DeclContext*, MultipleDC*> DeclCtx;

bool isInSemaDC() const { return DeclCtx.is<DeclContext*>(); }
bool isOutOfSemaDC() const { return DeclCtx.is<MultipleDC*>(); }

MultipleDC *getMultipleDC() const {
  return DeclCtx.get<MultipleDC*>();
}

DeclContext *getSemanticDC() const {
  return DeclCtx.get<DeclContext*>();
}

/// Loc - The location of this decl.
SourceLocation Loc;

/// DeclKind - This indicates which class this is.
unsigned DeclKind : 7;

/// InvalidDecl - This indicates a semantic error occurred.
unsigned InvalidDecl :  1;

/// HasAttrs - This indicates whether the decl has attributes or not.
unsigned HasAttrs : 1;

/// Implicit - Whether this declaration was implicitly generated by
/// the implementation rather than explicitly written by the user.
unsigned Implicit : 1;

/// Whether this declaration was "used", meaning that a definition is
/// required.
unsigned Used : 1;

/// Whether this declaration was "referenced".
/// The difference with 'Used' is whether the reference appears in a
/// evaluated context or not, e.g. functions used in uninstantiated templates
/// are regarded as "referenced" but not "used".
unsigned Referenced : 1;

/// Whether this declaration is a top-level declaration (function,
/// global variable, etc.) that is lexically inside an objc container
/// definition.
unsigned TopLevelDeclInObjCContainer : 1;

/// Whether statistic collection is enabled.
static bool StatisticsEnabled;

315protected:
friend class ASTDeclReader;
friend class ASTDeclWriter;
friend class ASTNodeImporter;
friend class ASTReader;
friend class CXXClassMemberWrapper;
friend class LinkageComputer;
template<typename decl_type> friend class Redeclarable;

/// Access - Used by C++ decls for the access specifier.
// NOTE: VC++ treats enums as signed, avoid using the AccessSpecifier enum
unsigned Access : 2;

/// Whether this declaration was loaded from an AST file.
unsigned FromASTFile : 1;

/// IdentifierNamespace - This specifies what IDNS_* namespace this lives in.
unsigned IdentifierNamespace : 14;

/// If 0, we have not computed the linkage of this declaration.
/// Otherwise, it is the linkage + 1.
mutable unsigned CacheValidAndLinkage : 3;

/// Allocate memory for a deserialized declaration.
///
/// This routine must be used to allocate memory for any declaration that is
/// deserialized from a module file.
///
/// \param Size The size of the allocated object.
/// \param Ctx The context in which we will allocate memory.
/// \param ID The global ID of the deserialized declaration.
/// \param Extra The amount of extra space to allocate after the object.
void *operator new(std::size_t Size, const ASTContext &Ctx, unsigned ID,
                   std::size_t Extra = 0);

/// Allocate memory for a non-deserialized declaration.
void *operator new(std::size_t Size, const ASTContext &Ctx,
                   DeclContext *Parent, std::size_t Extra = 0);

354private:
bool AccessDeclContextSanity() const;

/// Get the module ownership kind to use for a local lexical child of \p DC,
/// which may be either a local or (rarely) an imported declaration.
static ModuleOwnershipKind getModuleOwnershipKindForChildOf(DeclContext *DC) {
  if (DC) {
    auto *D = cast<Decl>(DC);
    auto MOK = D->getModuleOwnershipKind();
    if (MOK != ModuleOwnershipKind::Unowned &&
        (!D->isFromASTFile() || D->hasLocalOwningModuleStorage()))
      return MOK;
    // If D is not local and we have no local module storage, then we don't
    // need to track module ownership at all.
  }
  return ModuleOwnershipKind::Unowned;
}

372public:
Decl() = delete;
Decl(const Decl&) = delete;
Decl(Decl &&) = delete;
Decl &operator=(const Decl&) = delete;
Decl &operator=(Decl&&) = delete;

379protected:
Decl(Kind DK, DeclContext *DC, SourceLocation L)
    : NextInContextAndBits(nullptr, getModuleOwnershipKindForChildOf(DC)),
      DeclCtx(DC), Loc(L), DeclKind(DK), InvalidDecl(false), HasAttrs(false),
      Implicit(false), Used(false), Referenced(false),
      TopLevelDeclInObjCContainer(false), Access(AS_none), FromASTFile(0),
      IdentifierNamespace(getIdentifierNamespaceForKind(DK)),
      CacheValidAndLinkage(0) {
  if (StatisticsEnabled) add(DK);
}

Decl(Kind DK, EmptyShell Empty)
    : DeclKind(DK), InvalidDecl(false), HasAttrs(false), Implicit(false),
      Used(false), Referenced(false), TopLevelDeclInObjCContainer(false),
      Access(AS_none), FromASTFile(0),
      IdentifierNamespace(getIdentifierNamespaceForKind(DK)),
      CacheValidAndLinkage(0) {
  if (StatisticsEnabled) add(DK);
}

virtual ~Decl();

/// Update a potentially out-of-date declaration.
void updateOutOfDate(IdentifierInfo &II) const;

Linkage getCachedLinkage() const {
  return Linkage(CacheValidAndLinkage - 1);
}

void setCachedLinkage(Linkage L) const {
  CacheValidAndLinkage = L + 1;
}

bool hasCachedLinkage() const {
  return CacheValidAndLinkage;
}

416public:
/// Source range that this declaration covers.
virtual SourceRange getSourceRange() const LLVM_READONLY__attribute__((__pure__)) {
  return SourceRange(getLocation(), getLocation());
}

SourceLocation getBeginLoc() const LLVM_READONLY__attribute__((__pure__)) {
  return getSourceRange().getBegin();
}

SourceLocation getEndLoc() const LLVM_READONLY__attribute__((__pure__)) {
  return getSourceRange().getEnd();
}

SourceLocation getLocation() const { return Loc; }
void setLocation(SourceLocation L) { Loc = L; }

Kind getKind() const { return static_cast<Kind>(DeclKind); }
const char *getDeclKindName() const;

Decl *getNextDeclInContext() { return NextInContextAndBits.getPointer(); }
const Decl *getNextDeclInContext() const {return NextInContextAndBits.getPointer();}

DeclContext *getDeclContext() {
  if (isInSemaDC())
    return getSemanticDC();
  return getMultipleDC()->SemanticDC;
}
const DeclContext *getDeclContext() const {
  return const_cast<Decl*>(this)->getDeclContext();
}

/// Find the innermost non-closure ancestor of this declaration,
/// walking up through blocks, lambdas, etc.  If that ancestor is
/// not a code context (!isFunctionOrMethod()), returns null.
///
/// A declaration may be its own non-closure context.
Decl *getNonClosureContext();
const Decl *getNonClosureContext() const {
  return const_cast<Decl*>(this)->getNonClosureContext();
}

TranslationUnitDecl *getTranslationUnitDecl();
const TranslationUnitDecl *getTranslationUnitDecl() const {
  return const_cast<Decl*>(this)->getTranslationUnitDecl();
}

bool isInAnonymousNamespace() const;

bool isInStdNamespace() const;

ASTContext &getASTContext() const LLVM_READONLY__attribute__((__pure__));

/// Helper to get the language options from the ASTContext.
/// Defined out of line to avoid depending on ASTContext.h.
const LangOptions &getLangOpts() const LLVM_READONLY__attribute__((__pure__));

void setAccess(AccessSpecifier AS) {
  Access = AS;
  assert(AccessDeclContextSanity())((void)0);
}

AccessSpecifier getAccess() const {
  assert(AccessDeclContextSanity())((void)0);
  return AccessSpecifier(Access);
}

/// Retrieve the access specifier for this declaration, even though
/// it may not yet have been properly set.
AccessSpecifier getAccessUnsafe() const {
  return AccessSpecifier(Access);
}

bool hasAttrs() const { return HasAttrs; }

void setAttrs(const AttrVec& Attrs) {
  return setAttrsImpl(Attrs, getASTContext());
}

AttrVec &getAttrs() {
  return const_cast<AttrVec&>(const_cast<const Decl*>(this)->getAttrs());
}

const AttrVec &getAttrs() const;
void dropAttrs();
void addAttr(Attr *A);

using attr_iterator = AttrVec::const_iterator;
using attr_range = llvm::iterator_range<attr_iterator>;

attr_range attrs() const {
  return attr_range(attr_begin(), attr_end());
}

attr_iterator attr_begin() const {
  return hasAttrs() ? getAttrs().begin() : nullptr;
}
attr_iterator attr_end() const {
  return hasAttrs() ? getAttrs().end() : nullptr;
}

template <typename T>
void dropAttr() {
  if (!HasAttrs) return;

  AttrVec &Vec = getAttrs();
  llvm::erase_if(Vec, [](Attr *A) { return isa<T>(A); });

  if (Vec.empty())
    HasAttrs = false;
}

template <typename T>
llvm::iterator_range<specific_attr_iterator<T>> specific_attrs() const {
  return llvm::make_range(specific_attr_begin<T>(), specific_attr_end<T>());
}

template <typename T>
specific_attr_iterator<T> specific_attr_begin() const {
  return specific_attr_iterator<T>(attr_begin());
}

template <typename T>
specific_attr_iterator<T> specific_attr_end() const {
  return specific_attr_iterator<T>(attr_end());
}

template<typename T> T *getAttr() const {
  return hasAttrs() ? getSpecificAttr<T>(getAttrs()) : nullptr;
}

template<typename T> bool hasAttr() const {
  return hasAttrs() && hasSpecificAttr<T>(getAttrs());
}

/// getMaxAlignment - return the maximum alignment specified by attributes
/// on this decl, 0 if there are none.
unsigned getMaxAlignment() const;

/// setInvalidDecl - Indicates the Decl had a semantic error. This
/// allows for graceful error recovery.
void setInvalidDecl(bool Invalid = true);
bool isInvalidDecl() const { return (bool) InvalidDecl; }

/// isImplicit - Indicates whether the declaration was implicitly
/// generated by the implementation. If false, this declaration
/// was written explicitly in the source code.
bool isImplicit() const { return Implicit; }
void setImplicit(bool I = true) { Implicit = I; }

/// Whether *any* (re-)declaration of the entity was used, meaning that
/// a definition is required.
///
/// \param CheckUsedAttr When true, also consider the "used" attribute
/// (in addition to the "used" bit set by \c setUsed()) when determining
/// whether the function is used.
bool isUsed(bool CheckUsedAttr = true) const;

/// Set whether the declaration is used, in the sense of odr-use.
///
/// This should only be used immediately after creating a declaration.
/// It intentionally doesn't notify any listeners.
void setIsUsed() { getCanonicalDecl()->Used = true; }

/// Mark the declaration used, in the sense of odr-use.
///
/// This notifies any mutation listeners in addition to setting a bit
/// indicating the declaration is used.
void markUsed(ASTContext &C);

/// Whether any declaration of this entity was referenced.
bool isReferenced() const;

/// Whether this declaration was referenced. This should not be relied
/// upon for anything other than debugging.
bool isThisDeclarationReferenced() const { return Referenced; }

void setReferenced(bool R = true) { Referenced = R; }

/// Whether this declaration is a top-level declaration (function,
/// global variable, etc.) that is lexically inside an objc container
/// definition.
bool isTopLevelDeclInObjCContainer() const {
  return TopLevelDeclInObjCContainer;
}

void setTopLevelDeclInObjCContainer(bool V = true) {
  TopLevelDeclInObjCContainer = V;
}

/// Looks on this and related declarations for an applicable
/// external source symbol attribute.
ExternalSourceSymbolAttr *getExternalSourceSymbolAttr() const;

/// Whether this declaration was marked as being private to the
/// module in which it was defined.
bool isModulePrivate() const {
  return getModuleOwnershipKind() == ModuleOwnershipKind::ModulePrivate;
}

/// Return true if this declaration has an attribute which acts as
/// definition of the entity, such as 'alias' or 'ifunc'.
bool hasDefiningAttr() const;

/// Return this declaration's defining attribute if it has one.
const Attr *getDefiningAttr() const;

623protected:
/// Specify that this declaration was marked as being private
/// to the module in which it was defined.
void setModulePrivate() {
  // The module-private specifier has no effect on unowned declarations.
  // FIXME: We should track this in some way for source fidelity.
  if (getModuleOwnershipKind() == ModuleOwnershipKind::Unowned)
    return;
  setModuleOwnershipKind(ModuleOwnershipKind::ModulePrivate);
}

634public:
/// Set the FromASTFile flag. This indicates that this declaration
/// was deserialized and not parsed from source code and enables
/// features such as module ownership information.
void setFromASTFile() {
  FromASTFile = true;
}

/// Set the owning module ID.  This may only be called for
/// deserialized Decls.
void setOwningModuleID(unsigned ID) {
  assert(isFromASTFile() && "Only works on a deserialized declaration")((void)0);
  *((unsigned*)this - 2) = ID;
}

649public:
/// Determine the availability of the given declaration.
///
/// This routine will determine the most restrictive availability of
/// the given declaration (e.g., preferring 'unavailable' to
/// 'deprecated').
///
/// \param Message If non-NULL and the result is not \c
/// AR_Available, will be set to a (possibly empty) message
/// describing why the declaration has not been introduced, is
/// deprecated, or is unavailable.
///
/// \param EnclosingVersion The version to compare with. If empty, assume the
/// deployment target version.
///
/// \param RealizedPlatform If non-NULL and the availability result is found
/// in an available attribute it will set to the platform which is written in
/// the available attribute.
AvailabilityResult
getAvailability(std::string *Message = nullptr,
                VersionTuple EnclosingVersion = VersionTuple(),
                StringRef *RealizedPlatform = nullptr) const;

/// Retrieve the version of the target platform in which this
/// declaration was introduced.
///
/// \returns An empty version tuple if this declaration has no 'introduced'
/// availability attributes, or the version tuple that's specified in the
/// attribute otherwise.
VersionTuple getVersionIntroduced() const;

/// Determine whether this declaration is marked 'deprecated'.
///
/// \param Message If non-NULL and the declaration is deprecated,
/// this will be set to the message describing why the declaration
/// was deprecated (which may be empty).
bool isDeprecated(std::string *Message = nullptr) const {
  return getAvailability(Message) == AR_Deprecated;
}

/// Determine whether this declaration is marked 'unavailable'.
///
/// \param Message If non-NULL and the declaration is unavailable,
/// this will be set to the message describing why the declaration
/// was made unavailable (which may be empty).
bool isUnavailable(std::string *Message = nullptr) const {
  return getAvailability(Message) == AR_Unavailable;
}

/// Determine whether this is a weak-imported symbol.
///
/// Weak-imported symbols are typically marked with the
/// 'weak_import' attribute, but may also be marked with an
/// 'availability' attribute where we're targing a platform prior to
/// the introduction of this feature.
bool isWeakImported() const;

/// Determines whether this symbol can be weak-imported,
/// e.g., whether it would be well-formed to add the weak_import
/// attribute.
///
/// \param IsDefinition Set to \c true to indicate that this
/// declaration cannot be weak-imported because it has a definition.
bool canBeWeakImported(bool &IsDefinition) const;

/// Determine whether this declaration came from an AST file (such as
/// a precompiled header or module) rather than having been parsed.
bool isFromASTFile() const { return FromASTFile; }

/// Retrieve the global declaration ID associated with this
/// declaration, which specifies where this Decl was loaded from.
unsigned getGlobalID() const {
  if (isFromASTFile())
    return *((const unsigned*)this - 1);
  return 0;
}

/// Retrieve the global ID of the module that owns this particular
/// declaration.
unsigned getOwningModuleID() const {
  if (isFromASTFile())
    return *((const unsigned*)this - 2);
  return 0;
}

734private:
Module *getOwningModuleSlow() const;

737protected:
bool hasLocalOwningModuleStorage() const;

740public:
/// Get the imported owning module, if this decl is from an imported
/// (non-local) module.
Module *getImportedOwningModule() const {
  if (!isFromASTFile() || !hasOwningModule())
    return nullptr;

  return getOwningModuleSlow();
}

/// Get the local owning module, if known. Returns nullptr if owner is
/// not yet known or declaration is not from a module.
Module *getLocalOwningModule() const {
  if (isFromASTFile() || !hasOwningModule())
    return nullptr;

  assert(hasLocalOwningModuleStorage() &&((void)0)
         "owned local decl but no local module storage")((void)0);
  return reinterpret_cast<Module *const *>(this)[-1];
}
void setLocalOwningModule(Module *M) {
  assert(!isFromASTFile() && hasOwningModule() &&((void)0)
         hasLocalOwningModuleStorage() &&((void)0)
         "should not have a cached owning module")((void)0);
  reinterpret_cast<Module **>(this)[-1] = M;
}

/// Is this declaration owned by some module?
bool hasOwningModule() const {
  return getModuleOwnershipKind() != ModuleOwnershipKind::Unowned;
}

/// Get the module that owns this declaration (for visibility purposes).
Module *getOwningModule() const {
  return isFromASTFile() ? getImportedOwningModule() : getLocalOwningModule();
}

/// Get the module that owns this declaration for linkage purposes.
/// There only ever is such a module under the C++ Modules TS.
///
/// \param IgnoreLinkage Ignore the linkage of the entity; assume that
/// all declarations in a global module fragment are unowned.
Module *getOwningModuleForLinkage(bool IgnoreLinkage = false) const;

/// Determine whether this declaration is definitely visible to name lookup,
/// independent of whether the owning module is visible.
/// Note: The declaration may be visible even if this returns \c false if the
/// owning module is visible within the query context. This is a low-level
/// helper function; most code should be calling Sema::isVisible() instead.
bool isUnconditionallyVisible() const {
  return (int)getModuleOwnershipKind() <= (int)ModuleOwnershipKind::Visible;
}

/// Set that this declaration is globally visible, even if it came from a
/// module that is not visible.
void setVisibleDespiteOwningModule() {
  if (!isUnconditionallyVisible())
    setModuleOwnershipKind(ModuleOwnershipKind::Visible);
}

/// Get the kind of module ownership for this declaration.
ModuleOwnershipKind getModuleOwnershipKind() const {
  return NextInContextAndBits.getInt();
}

/// Set whether this declaration is hidden from name lookup.
void setModuleOwnershipKind(ModuleOwnershipKind MOK) {
  assert(!(getModuleOwnershipKind() == ModuleOwnershipKind::Unowned &&((void)0)
           MOK != ModuleOwnershipKind::Unowned && !isFromASTFile() &&((void)0)
           !hasLocalOwningModuleStorage()) &&((void)0)
         "no storage available for owning module for this declaration")((void)0);
  NextInContextAndBits.setInt(MOK);
}

unsigned getIdentifierNamespace() const {
  return IdentifierNamespace;
}

bool isInIdentifierNamespace(unsigned NS) const {
  return getIdentifierNamespace() & NS;
}

static unsigned getIdentifierNamespaceForKind(Kind DK);

bool hasTagIdentifierNamespace() const {
  return isTagIdentifierNamespace(getIdentifierNamespace());
}

static bool isTagIdentifierNamespace(unsigned NS) {
  // TagDecls have Tag and Type set and may also have TagFriend.
  return (NS & ~IDNS_TagFriend) == (IDNS_Tag | IDNS_Type);
}

/// getLexicalDeclContext - The declaration context where this Decl was
/// lexically declared (LexicalDC). May be different from
/// getDeclContext() (SemanticDC).
/// e.g.:
///
///   namespace A {
///      void f(); // SemanticDC == LexicalDC == 'namespace A'
///   }
///   void A::f(); // SemanticDC == namespace 'A'
///                // LexicalDC == global namespace
DeclContext *getLexicalDeclContext() {
  if (isInSemaDC())
    return getSemanticDC();
  return getMultipleDC()->LexicalDC;
}
const DeclContext *getLexicalDeclContext() const {
  return const_cast<Decl*>(this)->getLexicalDeclContext();
}

/// Determine whether this declaration is declared out of line (outside its
/// semantic context).
virtual bool isOutOfLine() const;

/// setDeclContext - Set both the semantic and lexical DeclContext
/// to DC.
void setDeclContext(DeclContext *DC);

void setLexicalDeclContext(DeclContext *DC);

/// Determine whether this declaration is a templated entity (whether it is
// within the scope of a template parameter).
bool isTemplated() const;

/// Determine the number of levels of template parameter surrounding this
/// declaration.
unsigned getTemplateDepth() const;

/// isDefinedOutsideFunctionOrMethod - This predicate returns true if this
/// scoped decl is defined outside the current function or method.  This is
/// roughly global variables and functions, but also handles enums (which
/// could be defined inside or outside a function etc).
bool isDefinedOutsideFunctionOrMethod() const {
  return getParentFunctionOrMethod() == nullptr;
}

/// Determine whether a substitution into this declaration would occur as
/// part of a substitution into a dependent local scope. Such a substitution
/// transitively substitutes into all constructs nested within this
/// declaration.
///
/// This recognizes non-defining declarations as well as members of local
/// classes and lambdas:
/// \code
///     template<typename T> void foo() { void bar(); }
///     template<typename T> void foo2() { class ABC { void bar(); }; }
///     template<typename T> inline int x = [](){ return 0; }();
/// \endcode
bool isInLocalScopeForInstantiation() const;

/// If this decl is defined inside a function/method/block it returns
/// the corresponding DeclContext, otherwise it returns null.
const DeclContext *getParentFunctionOrMethod() const;
DeclContext *getParentFunctionOrMethod() {
  return const_cast<DeclContext*>(
                  const_cast<const Decl*>(this)->getParentFunctionOrMethod());
}

/// Retrieves the "canonical" declaration of the given declaration.
virtual Decl *getCanonicalDecl() { return this; }
const Decl *getCanonicalDecl() const {
  return const_cast<Decl*>(this)->getCanonicalDecl();
}

/// Whether this particular Decl is a canonical one.
bool isCanonicalDecl() const { return getCanonicalDecl() == this; }

909protected:
/// Returns the next redeclaration or itself if this is the only decl.
///
/// Decl subclasses that can be redeclared should override this method so that
/// Decl::redecl_iterator can iterate over them.
virtual Decl *getNextRedeclarationImpl() { return this; }

/// Implementation of getPreviousDecl(), to be overridden by any
/// subclass that has a redeclaration chain.
virtual Decl *getPreviousDeclImpl() { return nullptr; }

/// Implementation of getMostRecentDecl(), to be overridden by any
/// subclass that has a redeclaration chain.
virtual Decl *getMostRecentDeclImpl() { return this; }

924public:
/// Iterates through all the redeclarations of the same decl.
class redecl_iterator {
  /// Current - The current declaration.
  Decl *Current = nullptr;
  Decl *Starter;

public:
  using value_type = Decl *;
  using reference = const value_type &;
  using pointer = const value_type *;
  using iterator_category = std::forward_iterator_tag;
  using difference_type = std::ptrdiff_t;

  redecl_iterator() = default;
  explicit redecl_iterator(Decl *C) : Current(C), Starter(C) {}

  reference operator*() const { return Current; }
  value_type operator->() const { return Current; }

  redecl_iterator& operator++() {
    assert(Current && "Advancing while iterator has reached end")((void)0);
    // Get either previous decl or latest decl.
    Decl *Next = Current->getNextRedeclarationImpl();
    assert(Next && "Should return next redeclaration or itself, never null!")((void)0);
    Current = (Next != Starter) ? Next : nullptr;
    return *this;
  }

  redecl_iterator operator++(int) {
    redecl_iterator tmp(*this);
    ++(*this);
    return tmp;
  }

  friend bool operator==(redecl_iterator x, redecl_iterator y) {
    return x.Current == y.Current;
  }

  friend bool operator!=(redecl_iterator x, redecl_iterator y) {
    return x.Current != y.Current;
  }
};

using redecl_range = llvm::iterator_range<redecl_iterator>;

/// Returns an iterator range for all the redeclarations of the same
/// decl. It will iterate at least once (when this decl is the only one).
redecl_range redecls() const {
  return redecl_range(redecls_begin(), redecls_end());
}

redecl_iterator redecls_begin() const {
  return redecl_iterator(const_cast<Decl *>(this));
}

redecl_iterator redecls_end() const { return redecl_iterator(); }

/// Retrieve the previous declaration that declares the same entity
/// as this declaration, or NULL if there is no previous declaration.
Decl *getPreviousDecl() { return getPreviousDeclImpl(); }

/// Retrieve the previous declaration that declares the same entity
/// as this declaration, or NULL if there is no previous declaration.
const Decl *getPreviousDecl() const {
  return const_cast<Decl *>(this)->getPreviousDeclImpl();
}

/// True if this is the first declaration in its redeclaration chain.
bool isFirstDecl() const {
  return getPreviousDecl() == nullptr;
}

/// Retrieve the most recent declaration that declares the same entity
/// as this declaration (which may be this declaration).
Decl *getMostRecentDecl() { return getMostRecentDeclImpl(); }

/// Retrieve the most recent declaration that declares the same entity
/// as this declaration (which may be this declaration).
const Decl *getMostRecentDecl() const {
  return const_cast<Decl *>(this)->getMostRecentDeclImpl();
}

/// getBody - If this Decl represents a declaration for a body of code,
///  such as a function or method definition, this method returns the
///  top-level Stmt* of that body.  Otherwise this method returns null.
virtual Stmt* getBody() const { return nullptr; }

/// Returns true if this \c Decl represents a declaration for a body of
/// code, such as a function or method definition.
/// Note that \c hasBody can also return true if any redeclaration of this
/// \c Decl represents a declaration for a body of code.
virtual bool hasBody() const { return getBody() != nullptr; }

/// getBodyRBrace - Gets the right brace of the body, if a body exists.
/// This works whether the body is a CompoundStmt or a CXXTryStmt.
SourceLocation getBodyRBrace() const;

// global temp stats (until we have a per-module visitor)
static void add(Kind k);
static void EnableStatistics();
static void PrintStats();

/// isTemplateParameter - Determines whether this declaration is a
/// template parameter.
bool isTemplateParameter() const;

/// isTemplateParameter - Determines whether this declaration is a
/// template parameter pack.
bool isTemplateParameterPack() const;

/// Whether this declaration is a parameter pack.
bool isParameterPack() const;

/// returns true if this declaration is a template
bool isTemplateDecl() const;

/// Whether this declaration is a function or function template.
bool isFunctionOrFunctionTemplate() const {
  return (DeclKind >= Decl::firstFunction &&
          DeclKind <= Decl::lastFunction) ||
         DeclKind == FunctionTemplate;
}

/// If this is a declaration that describes some template, this
/// method returns that template declaration.
///
/// Note that this returns nullptr for partial specializations, because they
/// are not modeled as TemplateDecls. Use getDescribedTemplateParams to handle
/// those cases.
TemplateDecl *getDescribedTemplate() const;

/// If this is a declaration that describes some template or partial
/// specialization, this returns the corresponding template parameter list.
const TemplateParameterList *getDescribedTemplateParams() const;

/// Returns the function itself, or the templated function if this is a
/// function template.
FunctionDecl *getAsFunction() LLVM_READONLY__attribute__((__pure__));

const FunctionDecl *getAsFunction() const {
  return const_cast<Decl *>(this)->getAsFunction();
}

/// Changes the namespace of this declaration to reflect that it's
/// a function-local extern declaration.
///
/// These declarations appear in the lexical context of the extern
/// declaration, but in the semantic context of the enclosing namespace
/// scope.
void setLocalExternDecl() {
  Decl *Prev = getPreviousDecl();
  IdentifierNamespace &= ~IDNS_Ordinary;

  // It's OK for the declaration to still have the "invisible friend" flag or
  // the "conflicts with tag declarations in this scope" flag for the outer
  // scope.
  assert((IdentifierNamespace & ~(IDNS_OrdinaryFriend | IDNS_Tag)) == 0 &&((void)0)
         "namespace is not ordinary")((void)0);

  IdentifierNamespace |= IDNS_LocalExtern;
  if (Prev && Prev->getIdentifierNamespace() & IDNS_Ordinary)
    IdentifierNamespace |= IDNS_Ordinary;
}

/// Determine whether this is a block-scope declaration with linkage.
/// This will either be a local variable declaration declared 'extern', or a
/// local function declaration.
bool isLocalExternDecl() {
  return IdentifierNamespace & IDNS_LocalExtern;
}

/// Changes the namespace of this declaration to reflect that it's
/// the object of a friend declaration.
///
/// These declarations appear in the lexical context of the friending
/// class, but in the semantic context of the actual entity.  This property
/// applies only to a specific decl object;  other redeclarations of the
/// same entity may not (and probably don't) share this property.
void setObjectOfFriendDecl(bool PerformFriendInjection = false) {
  unsigned OldNS = IdentifierNamespace;
  assert((OldNS & (IDNS_Tag | IDNS_Ordinary |((void)0)
                   IDNS_TagFriend | IDNS_OrdinaryFriend |((void)0)
                   IDNS_LocalExtern | IDNS_NonMemberOperator)) &&((void)0)
         "namespace includes neither ordinary nor tag")((void)0);
  assert(!(OldNS & ~(IDNS_Tag | IDNS_Ordinary | IDNS_Type |((void)0)
                     IDNS_TagFriend | IDNS_OrdinaryFriend |((void)0)
                     IDNS_LocalExtern | IDNS_NonMemberOperator)) &&((void)0)
         "namespace includes other than ordinary or tag")((void)0);

  Decl *Prev = getPreviousDecl();
  IdentifierNamespace &= ~(IDNS_Ordinary | IDNS_Tag | IDNS_Type);

  if (OldNS & (IDNS_Tag | IDNS_TagFriend)) {
    IdentifierNamespace |= IDNS_TagFriend;
    if (PerformFriendInjection ||
        (Prev && Prev->getIdentifierNamespace() & IDNS_Tag))
      IdentifierNamespace |= IDNS_Tag | IDNS_Type;
  }

  if (OldNS & (IDNS_Ordinary | IDNS_OrdinaryFriend |
               IDNS_LocalExtern | IDNS_NonMemberOperator)) {
    IdentifierNamespace |= IDNS_OrdinaryFriend;
    if (PerformFriendInjection ||
        (Prev && Prev->getIdentifierNamespace() & IDNS_Ordinary))
      IdentifierNamespace |= IDNS_Ordinary;
  }
}

enum FriendObjectKind {
  FOK_None,      ///< Not a friend object.
  FOK_Declared,  ///< A friend of a previously-declared entity.
  FOK_Undeclared ///< A friend of a previously-undeclared entity.
};

/// Determines whether this declaration is the object of a
/// friend declaration and, if so, what kind.
///
/// There is currently no direct way to find the associated FriendDecl.
FriendObjectKind getFriendObjectKind() const {
  unsigned mask =
      (IdentifierNamespace & (IDNS_TagFriend | IDNS_OrdinaryFriend));
  if (!mask) return FOK_None;
  return (IdentifierNamespace & (IDNS_Tag | IDNS_Ordinary) ? FOK_Declared
                                                           : FOK_Undeclared);
}

/// Specifies that this declaration is a C++ overloaded non-member.
void setNonMemberOperator() {
  assert(getKind() == Function || getKind() == FunctionTemplate)((void)0);
  assert((IdentifierNamespace & IDNS_Ordinary) &&((void)0)
         "visible non-member operators should be in ordinary namespace")((void)0);
  IdentifierNamespace |= IDNS_NonMemberOperator;
}

static bool classofKind(Kind K) { return true; }
static DeclContext *castToDeclContext(const Decl *);
static Decl *castFromDeclContext(const DeclContext *);

void print(raw_ostream &Out, unsigned Indentation = 0,
           bool PrintInstantiation = false) const;
void print(raw_ostream &Out, const PrintingPolicy &Policy,
           unsigned Indentation = 0, bool PrintInstantiation = false) const;
static void printGroup(Decl** Begin, unsigned NumDecls,
                       raw_ostream &Out, const PrintingPolicy &Policy,
                       unsigned Indentation = 0);

// Debuggers don't usually respect default arguments.
void dump() const;

// Same as dump(), but forces color printing.
void dumpColor() const;

void dump(raw_ostream &Out, bool Deserialize = false,
          ASTDumpOutputFormat OutputFormat = ADOF_Default) const;

/// \return Unique reproducible object identifier
int64_t getID() const;

/// Looks through the Decl's underlying type to extract a FunctionType
/// when possible. Will return null if the type underlying the Decl does not
/// have a FunctionType.
const FunctionType *getFunctionType(bool BlocksToo = true) const;

1188private:
void setAttrsImpl(const AttrVec& Attrs, ASTContext &Ctx);
void setDeclContextsImpl(DeclContext *SemaDC, DeclContext *LexicalDC,
                         ASTContext &Ctx);

1193protected:
ASTMutationListener *getASTMutationListener() const;
1195};

1197/// Determine whether two declarations declare the same entity.
1198inline bool declaresSameEntity(const Decl *D1, const Decl *D2) {
if (!D1 || !D2)
  return false;

if (D1 == D2)
  return true;

return D1->getCanonicalDecl() == D2->getCanonicalDecl();
1206}

1208/// PrettyStackTraceDecl - If a crash occurs, indicate that it happened when
1209/// doing something to a specific decl.
1210class PrettyStackTraceDecl : public llvm::PrettyStackTraceEntry {
const Decl *TheDecl;
SourceLocation Loc;
SourceManager &SM;
const char *Message;

1216public:
PrettyStackTraceDecl(const Decl *theDecl, SourceLocation L,
                     SourceManager &sm, const char *Msg)
    : TheDecl(theDecl), Loc(L), SM(sm), Message(Msg) {}

void print(raw_ostream &OS) const override;
1222};
1223} // namespace clang

1225// Required to determine the layout of the PointerUnion<NamedDecl*> before
1226// seeing the NamedDecl definition being first used in DeclListNode::operator*.
1227namespace llvm {
template <> struct PointerLikeTypeTraits<::clang::NamedDecl *> {
  static inline void *getAsVoidPointer(::clang::NamedDecl *P) { return P; }
  static inline ::clang::NamedDecl *getFromVoidPointer(void *P) {
    return static_cast<::clang::NamedDecl *>(P);
  }
  static constexpr int NumLowBitsAvailable = 3;
};
1235}

1237namespace clang {
1238/// A list storing NamedDecls in the lookup tables.
1239class DeclListNode {
friend class ASTContext; // allocate, deallocate nodes.
friend class StoredDeclsList;
1242public:
using Decls = llvm::PointerUnion<NamedDecl*, DeclListNode*>;
class iterator {
  friend class DeclContextLookupResult;
  friend class StoredDeclsList;

  Decls Ptr;
  iterator(Decls Node) : Ptr(Node) { }
public:
  using difference_type = ptrdiff_t;
  using value_type = NamedDecl*;
  using pointer = void;
  using reference = value_type;
  using iterator_category = std::forward_iterator_tag;

  iterator() = default;

  reference operator*() const {
    assert(Ptr && "dereferencing end() iterator")((void)0);
    if (DeclListNode *CurNode = Ptr.dyn_cast<DeclListNode*>())
      return CurNode->D;
    return Ptr.get<NamedDecl*>();
  }
  void operator->() const { } // Unsupported.
  bool operator==(const iterator &X) const { return Ptr == X.Ptr; }
  bool operator!=(const iterator &X) const { return Ptr != X.Ptr; }
  inline iterator &operator++() { // ++It
    assert(!Ptr.isNull() && "Advancing empty iterator")((void)0);

    if (DeclListNode *CurNode = Ptr.dyn_cast<DeclListNode*>())
      Ptr = CurNode->Rest;
    else
      Ptr = nullptr;
    return *this;
  }
  iterator operator++(int) { // It++
    iterator temp = *this;
    ++(*this);
    return temp;
  }
  // Enables the pattern for (iterator I =..., E = I.end(); I != E; ++I)
  iterator end() { return iterator(); }
};
1285private:
NamedDecl *D = nullptr;
Decls Rest = nullptr;
DeclListNode(NamedDecl *ND) : D(ND) {}
1289};

1291/// The results of name lookup within a DeclContext.
1292class DeclContextLookupResult {
using Decls = DeclListNode::Decls;

/// When in collection form, this is what the Data pointer points to.
Decls Result;

1298public:
DeclContextLookupResult() = default;
DeclContextLookupResult(Decls Result) : Result(Result) {}

using iterator = DeclListNode::iterator;
using const_iterator = iterator;
using reference = iterator::reference;

iterator begin() { return iterator(Result); }
iterator end() { return iterator(); }
const_iterator begin() const {
  return const_cast<DeclContextLookupResult*>(this)->begin();
}
const_iterator end() const { return iterator(); }

bool empty() const { return Result.isNull();  }
bool isSingleResult() const { return Result.dyn_cast<NamedDecl*>(); }
reference front() const { return *begin(); }

// Find the first declaration of the given type in the list. Note that this
// is not in general the earliest-declared declaration, and should only be
// used when it's not possible for there to be more than one match or where
// it doesn't matter which one is found.
template<class T> T *find_first() const {
  for (auto *D : *this)
    if (T *Decl = dyn_cast<T>(D))
      return Decl;

  return nullptr;
}
1328};

1330/// DeclContext - This is used only as base class of specific decl types that
1331/// can act as declaration contexts. These decls are (only the top classes
1332/// that directly derive from DeclContext are mentioned, not their subclasses):
1333///
1334///   TranslationUnitDecl
1335///   ExternCContext
1336///   NamespaceDecl
1337///   TagDecl
1338///   OMPDeclareReductionDecl
1339///   OMPDeclareMapperDecl
1340///   FunctionDecl
1341///   ObjCMethodDecl
1342///   ObjCContainerDecl
1343///   LinkageSpecDecl
1344///   ExportDecl
1345///   BlockDecl
1346///   CapturedDecl
1347class DeclContext {
/// For makeDeclVisibleInContextImpl
friend class ASTDeclReader;
/// For reconcileExternalVisibleStorage, CreateStoredDeclsMap,
/// hasNeedToReconcileExternalVisibleStorage
friend class ExternalASTSource;
/// For CreateStoredDeclsMap
friend class DependentDiagnostic;
/// For hasNeedToReconcileExternalVisibleStorage,
/// hasLazyLocalLexicalLookups, hasLazyExternalLexicalLookups
friend class ASTWriter;

// We use uint64_t in the bit-fields below since some bit-fields
// cross the unsigned boundary and this breaks the packing.

/// Stores the bits used by DeclContext.
/// If modified NumDeclContextBit, the ctor of DeclContext and the accessor
/// methods in DeclContext should be updated appropriately.
class DeclContextBitfields {
  friend class DeclContext;
  /// DeclKind - This indicates which class this is.
  uint64_t DeclKind : 7;

  /// Whether this declaration context also has some external
  /// storage that contains additional declarations that are lexically
  /// part of this context.
  mutable uint64_t ExternalLexicalStorage : 1;

  /// Whether this declaration context also has some external
  /// storage that contains additional declarations that are visible
  /// in this context.
  mutable uint64_t ExternalVisibleStorage : 1;

  /// Whether this declaration context has had externally visible
  /// storage added since the last lookup. In this case, \c LookupPtr's
  /// invariant may not hold and needs to be fixed before we perform
  /// another lookup.
  mutable uint64_t NeedToReconcileExternalVisibleStorage : 1;

  /// If \c true, this context may have local lexical declarations
  /// that are missing from the lookup table.
  mutable uint64_t HasLazyLocalLexicalLookups : 1;

  /// If \c true, the external source may have lexical declarations
  /// that are missing from the lookup table.
  mutable uint64_t HasLazyExternalLexicalLookups : 1;

  /// If \c true, lookups should only return identifier from
  /// DeclContext scope (for example TranslationUnit). Used in
  /// LookupQualifiedName()
  mutable uint64_t UseQualifiedLookup : 1;
};

/// Number of bits in DeclContextBitfields.
enum { NumDeclContextBits = 13 };

/// Stores the bits used by TagDecl.
/// If modified NumTagDeclBits and the accessor
/// methods in TagDecl should be updated appropriately.
class TagDeclBitfields {
  friend class TagDecl;
  /// For the bits in DeclContextBitfields
  uint64_t : NumDeclContextBits;

  /// The TagKind enum.
  uint64_t TagDeclKind : 3;

  /// True if this is a definition ("struct foo {};"), false if it is a
  /// declaration ("struct foo;").  It is not considered a definition
  /// until the definition has been fully processed.
  uint64_t IsCompleteDefinition : 1;

  /// True if this is currently being defined.
  uint64_t IsBeingDefined : 1;

  /// True if this tag declaration is "embedded" (i.e., defined or declared
  /// for the very first time) in the syntax of a declarator.
  uint64_t IsEmbeddedInDeclarator : 1;

  /// True if this tag is free standing, e.g. "struct foo;".
  uint64_t IsFreeStanding : 1;

  /// Indicates whether it is possible for declarations of this kind
  /// to have an out-of-date definition.
  ///
  /// This option is only enabled when modules are enabled.
  uint64_t MayHaveOutOfDateDef : 1;

  /// Has the full definition of this type been required by a use somewhere in
  /// the TU.
  uint64_t IsCompleteDefinitionRequired : 1;
};

/// Number of non-inherited bits in TagDeclBitfields.
enum { NumTagDeclBits = 9 };

/// Stores the bits used by EnumDecl.
/// If modified NumEnumDeclBit and the accessor
/// methods in EnumDecl should be updated appropriately.
class EnumDeclBitfields {
  friend class EnumDecl;
  /// For the bits in DeclContextBitfields.
  uint64_t : NumDeclContextBits;
  /// For the bits in TagDeclBitfields.
  uint64_t : NumTagDeclBits;

  /// Width in bits required to store all the non-negative
  /// enumerators of this enum.
  uint64_t NumPositiveBits : 8;

  /// Width in bits required to store all the negative
  /// enumerators of this enum.
  uint64_t NumNegativeBits : 8;

  /// True if this tag declaration is a scoped enumeration. Only
  /// possible in C++11 mode.
  uint64_t IsScoped : 1;

  /// If this tag declaration is a scoped enum,
  /// then this is true if the scoped enum was declared using the class
  /// tag, false if it was declared with the struct tag. No meaning is
  /// associated if this tag declaration is not a scoped enum.
  uint64_t IsScopedUsingClassTag : 1;

  /// True if this is an enumeration with fixed underlying type. Only
  /// possible in C++11, Microsoft extensions, or Objective C mode.
  uint64_t IsFixed : 1;

  /// True if a valid hash is stored in ODRHash.
  uint64_t HasODRHash : 1;
};

/// Number of non-inherited bits in EnumDeclBitfields.
enum { NumEnumDeclBits = 20 };

/// Stores the bits used by RecordDecl.
/// If modified NumRecordDeclBits and the accessor
/// methods in RecordDecl should be updated appropriately.
class RecordDeclBitfields {
  friend class RecordDecl;
  /// For the bits in DeclContextBitfields.
  uint64_t : NumDeclContextBits;
  /// For the bits in TagDeclBitfields.
  uint64_t : NumTagDeclBits;

  /// This is true if this struct ends with a flexible
  /// array member (e.g. int X[]) or if this union contains a struct that does.
  /// If so, this cannot be contained in arrays or other structs as a member.
  uint64_t HasFlexibleArrayMember : 1;

  /// Whether this is the type of an anonymous struct or union.
  uint64_t AnonymousStructOrUnion : 1;

  /// This is true if this struct has at least one member
  /// containing an Objective-C object pointer type.
  uint64_t HasObjectMember : 1;

  /// This is true if struct has at least one member of
  /// 'volatile' type.
  uint64_t HasVolatileMember : 1;

  /// Whether the field declarations of this record have been loaded
  /// from external storage. To avoid unnecessary deserialization of
  /// methods/nested types we allow deserialization of just the fields
  /// when needed.
  mutable uint64_t LoadedFieldsFromExternalStorage : 1;

  /// Basic properties of non-trivial C structs.
  uint64_t NonTrivialToPrimitiveDefaultInitialize : 1;
  uint64_t NonTrivialToPrimitiveCopy : 1;
  uint64_t NonTrivialToPrimitiveDestroy : 1;

  /// The following bits indicate whether this is or contains a C union that
  /// is non-trivial to default-initialize, destruct, or copy. These bits
  /// imply the associated basic non-triviality predicates declared above.
  uint64_t HasNonTrivialToPrimitiveDefaultInitializeCUnion : 1;
  uint64_t HasNonTrivialToPrimitiveDestructCUnion : 1;
  uint64_t HasNonTrivialToPrimitiveCopyCUnion : 1;

  /// Indicates whether this struct is destroyed in the callee.
  uint64_t ParamDestroyedInCallee : 1;

  /// Represents the way this type is passed to a function.
  uint64_t ArgPassingRestrictions : 2;
};

/// Number of non-inherited bits in RecordDeclBitfields.
enum { NumRecordDeclBits = 14 };

/// Stores the bits used by OMPDeclareReductionDecl.
/// If modified NumOMPDeclareReductionDeclBits and the accessor
/// methods in OMPDeclareReductionDecl should be updated appropriately.
class OMPDeclareReductionDeclBitfields {
  friend class OMPDeclareReductionDecl;
  /// For the bits in DeclContextBitfields
  uint64_t : NumDeclContextBits;

  /// Kind of initializer,
  /// function call or omp_priv<init_expr> initializtion.
  uint64_t InitializerKind : 2;
};

/// Number of non-inherited bits in OMPDeclareReductionDeclBitfields.
enum { NumOMPDeclareReductionDeclBits = 2 };

/// Stores the bits used by FunctionDecl.
/// If modified NumFunctionDeclBits and the accessor
/// methods in FunctionDecl and CXXDeductionGuideDecl
/// (for IsCopyDeductionCandidate) should be updated appropriately.
class FunctionDeclBitfields {
  friend class FunctionDecl;
  /// For IsCopyDeductionCandidate
  friend class CXXDeductionGuideDecl;
  /// For the bits in DeclContextBitfields.
  uint64_t : NumDeclContextBits;

  uint64_t SClass : 3;
  uint64_t IsInline : 1;
  uint64_t IsInlineSpecified : 1;

  uint64_t IsVirtualAsWritten : 1;
  uint64_t IsPure : 1;
  uint64_t HasInheritedPrototype : 1;
  uint64_t HasWrittenPrototype : 1;
  uint64_t IsDeleted : 1;
  /// Used by CXXMethodDecl
  uint64_t IsTrivial : 1;

  /// This flag indicates whether this function is trivial for the purpose of
  /// calls. This is meaningful only when this function is a copy/move
  /// constructor or a destructor.
  uint64_t IsTrivialForCall : 1;

  uint64_t IsDefaulted : 1;
  uint64_t IsExplicitlyDefaulted : 1;
  uint64_t HasDefaultedFunctionInfo : 1;
  uint64_t HasImplicitReturnZero : 1;
  uint64_t IsLateTemplateParsed : 1;

  /// Kind of contexpr specifier as defined by ConstexprSpecKind.
  uint64_t ConstexprKind : 2;
  uint64_t InstantiationIsPending : 1;

  /// Indicates if the function uses __try.
  uint64_t UsesSEHTry : 1;

  /// Indicates if the function was a definition
  /// but its body was skipped.
  uint64_t HasSkippedBody : 1;

  /// Indicates if the function declaration will
  /// have a body, once we're done parsing it.
  uint64_t WillHaveBody : 1;

  /// Indicates that this function is a multiversioned
  /// function using attribute 'target'.
  uint64_t IsMultiVersion : 1;

  /// [C++17] Only used by CXXDeductionGuideDecl. Indicates that
  /// the Deduction Guide is the implicitly generated 'copy
  /// deduction candidate' (is used during overload resolution).
  uint64_t IsCopyDeductionCandidate : 1;

  /// Store the ODRHash after first calculation.
  uint64_t HasODRHash : 1;

  /// Indicates if the function uses Floating Point Constrained Intrinsics
  uint64_t UsesFPIntrin : 1;
};

/// Number of non-inherited bits in FunctionDeclBitfields.
enum { NumFunctionDeclBits = 27 };

/// Stores the bits used by CXXConstructorDecl. If modified
/// NumCXXConstructorDeclBits and the accessor
/// methods in CXXConstructorDecl should be updated appropriately.
class CXXConstructorDeclBitfields {
  friend class CXXConstructorDecl;
  /// For the bits in DeclContextBitfields.
  uint64_t : NumDeclContextBits;
  /// For the bits in FunctionDeclBitfields.
  uint64_t : NumFunctionDeclBits;

  /// 24 bits to fit in the remaining available space.
  /// Note that this makes CXXConstructorDeclBitfields take
  /// exactly 64 bits and thus the width of NumCtorInitializers
  /// will need to be shrunk if some bit is added to NumDeclContextBitfields,
  /// NumFunctionDeclBitfields or CXXConstructorDeclBitfields.
  uint64_t NumCtorInitializers : 21;
  uint64_t IsInheritingConstructor : 1;

  /// Whether this constructor has a trail-allocated explicit specifier.
  uint64_t HasTrailingExplicitSpecifier : 1;
  /// If this constructor does't have a trail-allocated explicit specifier.
  /// Whether this constructor is explicit specified.
  uint64_t IsSimpleExplicit : 1;
};

/// Number of non-inherited bits in CXXConstructorDeclBitfields.
enum {
  NumCXXConstructorDeclBits = 64 - NumDeclContextBits - NumFunctionDeclBits
};

/// Stores the bits used by ObjCMethodDecl.
/// If modified NumObjCMethodDeclBits and the accessor
/// methods in ObjCMethodDecl should be updated appropriately.
class ObjCMethodDeclBitfields {
  friend class ObjCMethodDecl;

  /// For the bits in DeclContextBitfields.
  uint64_t : NumDeclContextBits;

  /// The conventional meaning of this method; an ObjCMethodFamily.
  /// This is not serialized; instead, it is computed on demand and
  /// cached.
  mutable uint64_t Family : ObjCMethodFamilyBitWidth;

  /// instance (true) or class (false) method.
  uint64_t IsInstance : 1;
  uint64_t IsVariadic : 1;

  /// True if this method is the getter or setter for an explicit property.
  uint64_t IsPropertyAccessor : 1;

  /// True if this method is a synthesized property accessor stub.
  uint64_t IsSynthesizedAccessorStub : 1;

  /// Method has a definition.
  uint64_t IsDefined : 1;

  /// Method redeclaration in the same interface.
  uint64_t IsRedeclaration : 1;

  /// Is redeclared in the same interface.
  mutable uint64_t HasRedeclaration : 1;

  /// \@required/\@optional
  uint64_t DeclImplementation : 2;

  /// in, inout, etc.
  uint64_t objcDeclQualifier : 7;

  /// Indicates whether this method has a related result type.
  uint64_t RelatedResultType : 1;

  /// Whether the locations of the selector identifiers are in a
  /// "standard" position, a enum SelectorLocationsKind.
  uint64_t SelLocsKind : 2;

  /// Whether this method overrides any other in the class hierarchy.
  ///
  /// A method is said to override any method in the class's
  /// base classes, its protocols, or its categories' protocols, that has
  /// the same selector and is of the same kind (class or instance).
  /// A method in an implementation is not considered as overriding the same
  /// method in the interface or its categories.
  uint64_t IsOverriding : 1;

  /// Indicates if the method was a definition but its body was skipped.
  uint64_t HasSkippedBody : 1;
};

/// Number of non-inherited bits in ObjCMethodDeclBitfields.
enum { NumObjCMethodDeclBits = 24 };

/// Stores the bits used by ObjCContainerDecl.
/// If modified NumObjCContainerDeclBits and the accessor
/// methods in ObjCContainerDecl should be updated appropriately.
class ObjCContainerDeclBitfields {
  friend class ObjCContainerDecl;
  /// For the bits in DeclContextBitfields
  uint32_t : NumDeclContextBits;

  // Not a bitfield but this saves space.
  // Note that ObjCContainerDeclBitfields is full.
  SourceLocation AtStart;
};

/// Number of non-inherited bits in ObjCContainerDeclBitfields.
/// Note that here we rely on the fact that SourceLocation is 32 bits
/// wide. We check this with the static_assert in the ctor of DeclContext.
enum { NumObjCContainerDeclBits = 64 - NumDeclContextBits };

/// Stores the bits used by LinkageSpecDecl.
/// If modified NumLinkageSpecDeclBits and the accessor
/// methods in LinkageSpecDecl should be updated appropriately.
class LinkageSpecDeclBitfields {
  friend class LinkageSpecDecl;
  /// For the bits in DeclContextBitfields.
  uint64_t : NumDeclContextBits;

  /// The language for this linkage specification with values
  /// in the enum LinkageSpecDecl::LanguageIDs.
  uint64_t Language : 3;

  /// True if this linkage spec has braces.
  /// This is needed so that hasBraces() returns the correct result while the
  /// linkage spec body is being parsed.  Once RBraceLoc has been set this is
  /// not used, so it doesn't need to be serialized.
  uint64_t HasBraces : 1;
};

/// Number of non-inherited bits in LinkageSpecDeclBitfields.
enum { NumLinkageSpecDeclBits = 4 };

/// Stores the bits used by BlockDecl.
/// If modified NumBlockDeclBits and the accessor
/// methods in BlockDecl should be updated appropriately.
class BlockDeclBitfields {
  friend class BlockDecl;
  /// For the bits in DeclContextBitfields.
  uint64_t : NumDeclContextBits;

  uint64_t IsVariadic : 1;
  uint64_t CapturesCXXThis : 1;
  uint64_t BlockMissingReturnType : 1;
  uint64_t IsConversionFromLambda : 1;

  /// A bit that indicates this block is passed directly to a function as a
  /// non-escaping parameter.
  uint64_t DoesNotEscape : 1;

  /// A bit that indicates whether it's possible to avoid coying this block to
  /// the heap when it initializes or is assigned to a local variable with
  /// automatic storage.
  uint64_t CanAvoidCopyToHeap : 1;
};

/// Number of non-inherited bits in BlockDeclBitfields.
enum { NumBlockDeclBits = 5 };

/// Pointer to the data structure used to lookup declarations
/// within this context (or a DependentStoredDeclsMap if this is a
/// dependent context). We maintain the invariant that, if the map
/// contains an entry for a DeclarationName (and we haven't lazily
/// omitted anything), then it contains all relevant entries for that
/// name (modulo the hasExternalDecls() flag).
mutable StoredDeclsMap *LookupPtr = nullptr;

1786protected:
/// This anonymous union stores the bits belonging to DeclContext and classes
/// deriving from it. The goal is to use otherwise wasted
/// space in DeclContext to store data belonging to derived classes.
/// The space saved is especially significient when pointers are aligned
/// to 8 bytes. In this case due to alignment requirements we have a
/// little less than 8 bytes free in DeclContext which we can use.
/// We check that none of the classes in this union is larger than
/// 8 bytes with static_asserts in the ctor of DeclContext.
union {
  DeclContextBitfields DeclContextBits;
  TagDeclBitfields TagDeclBits;
  EnumDeclBitfields EnumDeclBits;
  RecordDeclBitfields RecordDeclBits;
  OMPDeclareReductionDeclBitfields OMPDeclareReductionDeclBits;
  FunctionDeclBitfields FunctionDeclBits;
  CXXConstructorDeclBitfields CXXConstructorDeclBits;
  ObjCMethodDeclBitfields ObjCMethodDeclBits;
  ObjCContainerDeclBitfields ObjCContainerDeclBits;
  LinkageSpecDeclBitfields LinkageSpecDeclBits;
  BlockDeclBitfields BlockDeclBits;

  static_assert(sizeof(DeclContextBitfields) <= 8,
                "DeclContextBitfields is larger than 8 bytes!");
  static_assert(sizeof(TagDeclBitfields) <= 8,
                "TagDeclBitfields is larger than 8 bytes!");
  static_assert(sizeof(EnumDeclBitfields) <= 8,
                "EnumDeclBitfields is larger than 8 bytes!");
  static_assert(sizeof(RecordDeclBitfields) <= 8,
                "RecordDeclBitfields is larger than 8 bytes!");
  static_assert(sizeof(OMPDeclareReductionDeclBitfields) <= 8,
                "OMPDeclareReductionDeclBitfields is larger than 8 bytes!");
  static_assert(sizeof(FunctionDeclBitfields) <= 8,
                "FunctionDeclBitfields is larger than 8 bytes!");
  static_assert(sizeof(CXXConstructorDeclBitfields) <= 8,
                "CXXConstructorDeclBitfields is larger than 8 bytes!");
  static_assert(sizeof(ObjCMethodDeclBitfields) <= 8,
                "ObjCMethodDeclBitfields is larger than 8 bytes!");
  static_assert(sizeof(ObjCContainerDeclBitfields) <= 8,
                "ObjCContainerDeclBitfields is larger than 8 bytes!");
  static_assert(sizeof(LinkageSpecDeclBitfields) <= 8,
                "LinkageSpecDeclBitfields is larger than 8 bytes!");
  static_assert(sizeof(BlockDeclBitfields) <= 8,
                "BlockDeclBitfields is larger than 8 bytes!");
};

/// FirstDecl - The first declaration stored within this declaration
/// context.
mutable Decl *FirstDecl = nullptr;

/// LastDecl - The last declaration stored within this declaration
/// context. FIXME: We could probably cache this value somewhere
/// outside of the DeclContext, to reduce the size of DeclContext by
/// another pointer.
mutable Decl *LastDecl = nullptr;

/// Build up a chain of declarations.
///
/// \returns the first/last pair of declarations.
static std::pair<Decl *, Decl *>
BuildDeclChain(ArrayRef<Decl*> Decls, bool FieldsAlreadyLoaded);

DeclContext(Decl::Kind K);

1850public:
~DeclContext();

Decl::Kind getDeclKind() const {
  return static_cast<Decl::Kind>(DeclContextBits.DeclKind);
}

const char *getDeclKindName() const;

/// getParent - Returns the containing DeclContext.
DeclContext *getParent() {
  return cast<Decl>(this)->getDeclContext();
}
const DeclContext *getParent() const {
  return const_cast<DeclContext*>(this)->getParent();
}

/// getLexicalParent - Returns the containing lexical DeclContext. May be
/// different from getParent, e.g.:
///
///   namespace A {
///      struct S;
///   }
///   struct A::S {}; // getParent() == namespace 'A'
///                   // getLexicalParent() == translation unit
///
DeclContext *getLexicalParent() {
  return cast<Decl>(this)->getLexicalDeclContext();
}
const DeclContext *getLexicalParent() const {
  return const_cast<DeclContext*>(this)->getLexicalParent();
}

DeclContext *getLookupParent();

const DeclContext *getLookupParent() const {
  return const_cast<DeclContext*>(this)->getLookupParent();
}

ASTContext &getParentASTContext() const {
  return cast<Decl>(this)->getASTContext();
}

bool isClosure() const { return getDeclKind() == Decl::Block; }

/// Return this DeclContext if it is a BlockDecl. Otherwise, return the
/// innermost enclosing BlockDecl or null if there are no enclosing blocks.
const BlockDecl *getInnermostBlockDecl() const;

bool isObjCContainer() const {
  switch (getDeclKind()) {
  case Decl::ObjCCategory:
  case Decl::ObjCCategoryImpl:
  case Decl::ObjCImplementation:
  case Decl::ObjCInterface:
  case Decl::ObjCProtocol:
    return true;
  default:
    return false;
  }
}

bool isFunctionOrMethod() const {
  switch (getDeclKind()) {
  case Decl::Block:
  case Decl::Captured:
  case Decl::ObjCMethod:
    return true;
  default:
    return getDeclKind() >= Decl::firstFunction &&
           getDeclKind() <= Decl::lastFunction;
  }
}

/// Test whether the context supports looking up names.
bool isLookupContext() const {
  return !isFunctionOrMethod() && getDeclKind() != Decl::LinkageSpec &&
         getDeclKind() != Decl::Export;
}

bool isFileContext() const {
  return getDeclKind() == Decl::TranslationUnit ||
         getDeclKind() == Decl::Namespace;
}

bool isTranslationUnit() const {
  return getDeclKind() == Decl::TranslationUnit;
22
←
Assuming the condition is false→
23
←
Returning zero, which participates in a condition later→
}

bool isRecord() const {
  return getDeclKind() >= Decl::firstRecord &&
         getDeclKind() <= Decl::lastRecord;
}

bool isNamespace() const { return getDeclKind() == Decl::Namespace; }
32
←
Assuming the condition is true→
33
←
Returning the value 1, which participates in a condition later→

bool isStdNamespace() const;

bool isInlineNamespace() const;

/// Determines whether this context is dependent on a
/// template parameter.
bool isDependentContext() const;

/// isTransparentContext - Determines whether this context is a
/// "transparent" context, meaning that the members declared in this
/// context are semantically declared in the nearest enclosing
/// non-transparent (opaque) context but are lexically declared in
/// this context. For example, consider the enumerators of an
/// enumeration type:
/// @code
/// enum E {
///   Val1
/// };
/// @endcode
/// Here, E is a transparent context, so its enumerator (Val1) will
/// appear (semantically) that it is in the same context of E.
/// Examples of transparent contexts include: enumerations (except for
/// C++0x scoped enums), and C++ linkage specifications.
bool isTransparentContext() const;

/// Determines whether this context or some of its ancestors is a
/// linkage specification context that specifies C linkage.
bool isExternCContext() const;

/// Retrieve the nearest enclosing C linkage specification context.
const LinkageSpecDecl *getExternCContext() const;

/// Determines whether this context or some of its ancestors is a
/// linkage specification context that specifies C++ linkage.
bool isExternCXXContext() const;

/// Determine whether this declaration context is equivalent
/// to the declaration context DC.
bool Equals(const DeclContext *DC) const {
  return DC && this->getPrimaryContext() == DC->getPrimaryContext();
}

/// Determine whether this declaration context encloses the
/// declaration context DC.
bool Encloses(const DeclContext *DC) const;

/// Find the nearest non-closure ancestor of this context,
/// i.e. the innermost semantic parent of this context which is not
/// a closure.  A context may be its own non-closure ancestor.
Decl *getNonClosureAncestor();
const Decl *getNonClosureAncestor() const {
  return const_cast<DeclContext*>(this)->getNonClosureAncestor();
}

/// getPrimaryContext - There may be many different
/// declarations of the same entity (including forward declarations
/// of classes, multiple definitions of namespaces, etc.), each with
/// a different set of declarations. This routine returns the
/// "primary" DeclContext structure, which will contain the
/// information needed to perform name lookup into this context.
DeclContext *getPrimaryContext();
const DeclContext *getPrimaryContext() const {
  return const_cast<DeclContext*>(this)->getPrimaryContext();
}

/// getRedeclContext - Retrieve the context in which an entity conflicts with
/// other entities of the same name, or where it is a redeclaration if the
/// two entities are compatible. This skips through transparent contexts.
DeclContext *getRedeclContext();
const DeclContext *getRedeclContext() const {
  return const_cast<DeclContext *>(this)->getRedeclContext();
}

/// Retrieve the nearest enclosing namespace context.
DeclContext *getEnclosingNamespaceContext();
const DeclContext *getEnclosingNamespaceContext() const {
  return const_cast<DeclContext *>(this)->getEnclosingNamespaceContext();
}

/// Retrieve the outermost lexically enclosing record context.
RecordDecl *getOuterLexicalRecordContext();
const RecordDecl *getOuterLexicalRecordContext() const {
  return const_cast<DeclContext *>(this)->getOuterLexicalRecordContext();
}

/// Test if this context is part of the enclosing namespace set of
/// the context NS, as defined in C++0x [namespace.def]p9. If either context
/// isn't a namespace, this is equivalent to Equals().
///
/// The enclosing namespace set of a namespace is the namespace and, if it is
/// inline, its enclosing namespace, recursively.
bool InEnclosingNamespaceSetOf(const DeclContext *NS) const;

/// Collects all of the declaration contexts that are semantically
/// connected to this declaration context.
///
/// For declaration contexts that have multiple semantically connected but
/// syntactically distinct contexts, such as C++ namespaces, this routine
/// retrieves the complete set of such declaration contexts in source order.
/// For example, given:
///
/// \code
/// namespace N {
///   int x;
/// }
/// namespace N {
///   int y;
/// }
/// \endcode
///
/// The \c Contexts parameter will contain both definitions of N.
///
/// \param Contexts Will be cleared and set to the set of declaration
/// contexts that are semanticaly connected to this declaration context,
/// in source order, including this context (which may be the only result,
/// for non-namespace contexts).
void collectAllContexts(SmallVectorImpl<DeclContext *> &Contexts);

/// decl_iterator - Iterates through the declarations stored
/// within this context.
class decl_iterator {
  /// Current - The current declaration.
  Decl *Current = nullptr;

public:
  using value_type = Decl *;
  using reference = const value_type &;
  using pointer = const value_type *;
  using iterator_category = std::forward_iterator_tag;
  using difference_type = std::ptrdiff_t;

  decl_iterator() = default;
  explicit decl_iterator(Decl *C) : Current(C) {}

  reference operator*() const { return Current; }

  // This doesn't meet the iterator requirements, but it's convenient
  value_type operator->() const { return Current; }

  decl_iterator& operator++() {
    Current = Current->getNextDeclInContext();
    return *this;
  }

  decl_iterator operator++(int) {
    decl_iterator tmp(*this);
    ++(*this);
    return tmp;
  }

  friend bool operator==(decl_iterator x, decl_iterator y) {
    return x.Current == y.Current;
  }

  friend bool operator!=(decl_iterator x, decl_iterator y) {
    return x.Current != y.Current;
  }
};

using decl_range = llvm::iterator_range<decl_iterator>;

/// decls_begin/decls_end - Iterate over the declarations stored in
/// this context.
decl_range decls() const { return decl_range(decls_begin(), decls_end()); }
decl_iterator decls_begin() const;
decl_iterator decls_end() const { return decl_iterator(); }
bool decls_empty() const;

/// noload_decls_begin/end - Iterate over the declarations stored in this
/// context that are currently loaded; don't attempt to retrieve anything
/// from an external source.
decl_range noload_decls() const {
  return decl_range(noload_decls_begin(), noload_decls_end());
}
decl_iterator noload_decls_begin() const { return decl_iterator(FirstDecl); }
decl_iterator noload_decls_end() const { return decl_iterator(); }

/// specific_decl_iterator - Iterates over a subrange of
/// declarations stored in a DeclContext, providing only those that
/// are of type SpecificDecl (or a class derived from it). This
/// iterator is used, for example, to provide iteration over just
/// the fields within a RecordDecl (with SpecificDecl = FieldDecl).
template<typename SpecificDecl>
class specific_decl_iterator {
  /// Current - The current, underlying declaration iterator, which
  /// will either be NULL or will point to a declaration of
  /// type SpecificDecl.
  DeclContext::decl_iterator Current;

  /// SkipToNextDecl - Advances the current position up to the next
  /// declaration of type SpecificDecl that also meets the criteria
  /// required by Acceptable.
  void SkipToNextDecl() {
    while (*Current && !isa<SpecificDecl>(*Current))
      ++Current;
  }

public:
  using value_type = SpecificDecl *;
  // TODO: Add reference and pointer types (with some appropriate proxy type)
  // if we ever have a need for them.
  using reference = void;
  using pointer = void;
  using difference_type =
      std::iterator_traits<DeclContext::decl_iterator>::difference_type;
  using iterator_category = std::forward_iterator_tag;

  specific_decl_iterator() = default;

  /// specific_decl_iterator - Construct a new iterator over a
  /// subset of the declarations the range [C,
  /// end-of-declarations). If A is non-NULL, it is a pointer to a
  /// member function of SpecificDecl that should return true for
  /// all of the SpecificDecl instances that will be in the subset
  /// of iterators. For example, if you want Objective-C instance
  /// methods, SpecificDecl will be ObjCMethodDecl and A will be
  /// &ObjCMethodDecl::isInstanceMethod.
  explicit specific_decl_iterator(DeclContext::decl_iterator C) : Current(C) {
    SkipToNextDecl();
  }

  value_type operator*() const { return cast<SpecificDecl>(*Current); }

  // This doesn't meet the iterator requirements, but it's convenient
  value_type operator->() const { return **this; }

  specific_decl_iterator& operator++() {
    ++Current;
    SkipToNextDecl();
    return *this;
  }

  specific_decl_iterator operator++(int) {
    specific_decl_iterator tmp(*this);
    ++(*this);
    return tmp;
  }

  friend bool operator==(const specific_decl_iterator& x,
                         const specific_decl_iterator& y) {
    return x.Current == y.Current;
  }

  friend bool operator!=(const specific_decl_iterator& x,
                         const specific_decl_iterator& y) {
    return x.Current != y.Current;
  }
};

/// Iterates over a filtered subrange of declarations stored
/// in a DeclContext.
///
/// This iterator visits only those declarations that are of type
/// SpecificDecl (or a class derived from it) and that meet some
/// additional run-time criteria. This iterator is used, for
/// example, to provide access to the instance methods within an
/// Objective-C interface (with SpecificDecl = ObjCMethodDecl and
/// Acceptable = ObjCMethodDecl::isInstanceMethod).
template<typename SpecificDecl, bool (SpecificDecl::*Acceptable)() const>
class filtered_decl_iterator {
  /// Current - The current, underlying declaration iterator, which
  /// will either be NULL or will point to a declaration of
  /// type SpecificDecl.
  DeclContext::decl_iterator Current;

  /// SkipToNextDecl - Advances the current position up to the next
  /// declaration of type SpecificDecl that also meets the criteria
  /// required by Acceptable.
  void SkipToNextDecl() {
    while (*Current &&
           (!isa<SpecificDecl>(*Current) ||
            (Acceptable && !(cast<SpecificDecl>(*Current)->*Acceptable)())))
      ++Current;
  }

public:
  using value_type = SpecificDecl *;
  // TODO: Add reference and pointer types (with some appropriate proxy type)
  // if we ever have a need for them.
  using reference = void;
  using pointer = void;
  using difference_type =
      std::iterator_traits<DeclContext::decl_iterator>::difference_type;
  using iterator_category = std::forward_iterator_tag;

  filtered_decl_iterator() = default;

  /// filtered_decl_iterator - Construct a new iterator over a
  /// subset of the declarations the range [C,
  /// end-of-declarations). If A is non-NULL, it is a pointer to a
  /// member function of SpecificDecl that should return true for
  /// all of the SpecificDecl instances that will be in the subset
  /// of iterators. For example, if you want Objective-C instance
  /// methods, SpecificDecl will be ObjCMethodDecl and A will be
  /// &ObjCMethodDecl::isInstanceMethod.
  explicit filtered_decl_iterator(DeclContext::decl_iterator C) : Current(C) {
    SkipToNextDecl();
  }

  value_type operator*() const { return cast<SpecificDecl>(*Current); }
  value_type operator->() const { return cast<SpecificDecl>(*Current); }

  filtered_decl_iterator& operator++() {
    ++Current;
    SkipToNextDecl();
    return *this;
  }

  filtered_decl_iterator operator++(int) {
    filtered_decl_iterator tmp(*this);
    ++(*this);
    return tmp;
  }

  friend bool operator==(const filtered_decl_iterator& x,
                         const filtered_decl_iterator& y) {
    return x.Current == y.Current;
  }

  friend bool operator!=(const filtered_decl_iterator& x,
                         const filtered_decl_iterator& y) {
    return x.Current != y.Current;
  }
};

/// Add the declaration D into this context.
///
/// This routine should be invoked when the declaration D has first
/// been declared, to place D into the context where it was
/// (lexically) defined. Every declaration must be added to one
/// (and only one!) context, where it can be visited via
/// [decls_begin(), decls_end()). Once a declaration has been added
/// to its lexical context, the corresponding DeclContext owns the
/// declaration.
///
/// If D is also a NamedDecl, it will be made visible within its
/// semantic context via makeDeclVisibleInContext.
void addDecl(Decl *D);

/// Add the declaration D into this context, but suppress
/// searches for external declarations with the same name.
///
/// Although analogous in function to addDecl, this removes an
/// important check.  This is only useful if the Decl is being
/// added in response to an external search; in all other cases,
/// addDecl() is the right function to use.
/// See the ASTImporter for use cases.
void addDeclInternal(Decl *D);

/// Add the declaration D to this context without modifying
/// any lookup tables.
///
/// This is useful for some operations in dependent contexts where
/// the semantic context might not be dependent;  this basically
/// only happens with friends.
void addHiddenDecl(Decl *D);

/// Removes a declaration from this context.
void removeDecl(Decl *D);

/// Checks whether a declaration is in this context.
bool containsDecl(Decl *D) const;

/// Checks whether a declaration is in this context.
/// This also loads the Decls from the external source before the check.
bool containsDeclAndLoad(Decl *D) const;

using lookup_result = DeclContextLookupResult;
using lookup_iterator = lookup_result::iterator;

/// lookup - Find the declarations (if any) with the given Name in
/// this context. Returns a range of iterators that contains all of
/// the declarations with this name, with object, function, member,
/// and enumerator names preceding any tag name. Note that this
/// routine will not look into parent contexts.
lookup_result lookup(DeclarationName Name) const;

/// Find the declarations with the given name that are visible
/// within this context; don't attempt to retrieve anything from an
/// external source.
lookup_result noload_lookup(DeclarationName Name);

/// A simplistic name lookup mechanism that performs name lookup
/// into this declaration context without consulting the external source.
///
/// This function should almost never be used, because it subverts the
/// usual relationship between a DeclContext and the external source.
/// See the ASTImporter for the (few, but important) use cases.
///
/// FIXME: This is very inefficient; replace uses of it with uses of
/// noload_lookup.
void localUncachedLookup(DeclarationName Name,
                         SmallVectorImpl<NamedDecl *> &Results);

/// Makes a declaration visible within this context.
///
/// This routine makes the declaration D visible to name lookup
/// within this context and, if this is a transparent context,
/// within its parent contexts up to the first enclosing
/// non-transparent context. Making a declaration visible within a
/// context does not transfer ownership of a declaration, and a
/// declaration can be visible in many contexts that aren't its
/// lexical context.
///
/// If D is a redeclaration of an existing declaration that is
/// visible from this context, as determined by
/// NamedDecl::declarationReplaces, the previous declaration will be
/// replaced with D.
void makeDeclVisibleInContext(NamedDecl *D);

/// all_lookups_iterator - An iterator that provides a view over the results
/// of looking up every possible name.
class all_lookups_iterator;

using lookups_range = llvm::iterator_range<all_lookups_iterator>;

lookups_range lookups() const;
// Like lookups(), but avoids loading external declarations.
// If PreserveInternalState, avoids building lookup data structures too.
lookups_range noload_lookups(bool PreserveInternalState) const;

/// Iterators over all possible lookups within this context.
all_lookups_iterator lookups_begin() const;
all_lookups_iterator lookups_end() const;

/// Iterators over all possible lookups within this context that are
/// currently loaded; don't attempt to retrieve anything from an external
/// source.
all_lookups_iterator noload_lookups_begin() const;
all_lookups_iterator noload_lookups_end() const;

struct udir_iterator;

using udir_iterator_base =
    llvm::iterator_adaptor_base<udir_iterator, lookup_iterator,
                                typename lookup_iterator::iterator_category,
                                UsingDirectiveDecl *>;

struct udir_iterator : udir_iterator_base {
  udir_iterator(lookup_iterator I) : udir_iterator_base(I) {}

  UsingDirectiveDecl *operator*() const;
};

using udir_range = llvm::iterator_range<udir_iterator>;

udir_range using_directives() const;

// These are all defined in DependentDiagnostic.h.
class ddiag_iterator;

using ddiag_range = llvm::iterator_range<DeclContext::ddiag_iterator>;

inline ddiag_range ddiags() const;

// Low-level accessors

/// Mark that there are external lexical declarations that we need
/// to include in our lookup table (and that are not available as external
/// visible lookups). These extra lookup results will be found by walking
/// the lexical declarations of this context. This should be used only if
/// setHasExternalLexicalStorage() has been called on any decl context for
/// which this is the primary context.
void setMustBuildLookupTable() {
  assert(this == getPrimaryContext() &&((void)0)
         "should only be called on primary context")((void)0);
  DeclContextBits.HasLazyExternalLexicalLookups = true;
}

/// Retrieve the internal representation of the lookup structure.
/// This may omit some names if we are lazily building the structure.
StoredDeclsMap *getLookupPtr() const { return LookupPtr; }

/// Ensure the lookup structure is fully-built and return it.
StoredDeclsMap *buildLookup();

/// Whether this DeclContext has external storage containing
/// additional declarations that are lexically in this context.
bool hasExternalLexicalStorage() const {
  return DeclContextBits.ExternalLexicalStorage;
}

/// State whether this DeclContext has external storage for
/// declarations lexically in this context.
void setHasExternalLexicalStorage(bool ES = true) const {
  DeclContextBits.ExternalLexicalStorage = ES;
}

/// Whether this DeclContext has external storage containing
/// additional declarations that are visible in this context.
bool hasExternalVisibleStorage() const {
  return DeclContextBits.ExternalVisibleStorage;
}

/// State whether this DeclContext has external storage for
/// declarations visible in this context.
void setHasExternalVisibleStorage(bool ES = true) const {
  DeclContextBits.ExternalVisibleStorage = ES;
  if (ES && LookupPtr)
    DeclContextBits.NeedToReconcileExternalVisibleStorage = true;
}

/// Determine whether the given declaration is stored in the list of
/// declarations lexically within this context.
bool isDeclInLexicalTraversal(const Decl *D) const {
  return D && (D->NextInContextAndBits.getPointer() || D == FirstDecl ||
               D == LastDecl);
}

bool setUseQualifiedLookup(bool use = true) const {
  bool old_value = DeclContextBits.UseQualifiedLookup;
  DeclContextBits.UseQualifiedLookup = use;
  return old_value;
}

bool shouldUseQualifiedLookup() const {
  return DeclContextBits.UseQualifiedLookup;
}

static bool classof(const Decl *D);
static bool classof(const DeclContext *D) { return true; }

void dumpDeclContext() const;
void dumpLookups() const;
void dumpLookups(llvm::raw_ostream &OS, bool DumpDecls = false,
                 bool Deserialize = false) const;

2473private:
/// Whether this declaration context has had externally visible
/// storage added since the last lookup. In this case, \c LookupPtr's
/// invariant may not hold and needs to be fixed before we perform
/// another lookup.
bool hasNeedToReconcileExternalVisibleStorage() const {
  return DeclContextBits.NeedToReconcileExternalVisibleStorage;
}

/// State that this declaration context has had externally visible
/// storage added since the last lookup. In this case, \c LookupPtr's
/// invariant may not hold and needs to be fixed before we perform
/// another lookup.
void setNeedToReconcileExternalVisibleStorage(bool Need = true) const {
  DeclContextBits.NeedToReconcileExternalVisibleStorage = Need;
}

/// If \c true, this context may have local lexical declarations
/// that are missing from the lookup table.
bool hasLazyLocalLexicalLookups() const {
  return DeclContextBits.HasLazyLocalLexicalLookups;
}

/// If \c true, this context may have local lexical declarations
/// that are missing from the lookup table.
void setHasLazyLocalLexicalLookups(bool HasLLLL = true) const {
  DeclContextBits.HasLazyLocalLexicalLookups = HasLLLL;
}

/// If \c true, the external source may have lexical declarations
/// that are missing from the lookup table.
bool hasLazyExternalLexicalLookups() const {
  return DeclContextBits.HasLazyExternalLexicalLookups;
}

/// If \c true, the external source may have lexical declarations
/// that are missing from the lookup table.
void setHasLazyExternalLexicalLookups(bool HasLELL = true) const {
  DeclContextBits.HasLazyExternalLexicalLookups = HasLELL;
}

void reconcileExternalVisibleStorage() const;
bool LoadLexicalDeclsFromExternalStorage() const;

/// Makes a declaration visible within this context, but
/// suppresses searches for external declarations with the same
/// name.
///
/// Analogous to makeDeclVisibleInContext, but for the exclusive
/// use of addDeclInternal().
void makeDeclVisibleInContextInternal(NamedDecl *D);

StoredDeclsMap *CreateStoredDeclsMap(ASTContext &C) const;

void loadLazyLocalLexicalLookups();
void buildLookupImpl(DeclContext *DCtx, bool Internal);
void makeDeclVisibleInContextWithFlags(NamedDecl *D, bool Internal,
                                       bool Rediscoverable);
void makeDeclVisibleInContextImpl(NamedDecl *D, bool Internal);
2532};

2534inline bool Decl::isTemplateParameter() const {
return getKind() == TemplateTypeParm || getKind() == NonTypeTemplateParm ||
       getKind() == TemplateTemplateParm;
2537}

2539// Specialization selected when ToTy is not a known subclass of DeclContext.
2540template <class ToTy,
        bool IsKnownSubtype = ::std::is_base_of<DeclContext, ToTy>::value>
2542struct cast_convert_decl_context {
static const ToTy *doit(const DeclContext *Val) {
  return static_cast<const ToTy*>(Decl::castFromDeclContext(Val));
}

static ToTy *doit(DeclContext *Val) {
  return static_cast<ToTy*>(Decl::castFromDeclContext(Val));
}
2550};

2552// Specialization selected when ToTy is a known subclass of DeclContext.
2553template <class ToTy>
2554struct cast_convert_decl_context<ToTy, true> {
static const ToTy *doit(const DeclContext *Val) {
  return static_cast<const ToTy*>(Val);
}

static ToTy *doit(DeclContext *Val) {
  return static_cast<ToTy*>(Val);
}
2562};

2564} // namespace clang

2566namespace llvm {

2568/// isa<T>(DeclContext*)
2569template <typename To>
2570struct isa_impl<To, ::clang::DeclContext> {
static bool doit(const ::clang::DeclContext &Val) {
  return To::classofKind(Val.getDeclKind());
}
2574};

2576/// cast<T>(DeclContext*)
2577template<class ToTy>
2578struct cast_convert_val<ToTy,
                      const ::clang::DeclContext,const ::clang::DeclContext> {
static const ToTy &doit(const ::clang::DeclContext &Val) {
  return *::clang::cast_convert_decl_context<ToTy>::doit(&Val);
}
2583};

2585template<class ToTy>
2586struct cast_convert_val<ToTy, ::clang::DeclContext, ::clang::DeclContext> {
static ToTy &doit(::clang::DeclContext &Val) {
  return *::clang::cast_convert_decl_context<ToTy>::doit(&Val);
}
2590};

2592template<class ToTy>
2593struct cast_convert_val<ToTy,
                   const ::clang::DeclContext*, const ::clang::DeclContext*> {
static const ToTy *doit(const ::clang::DeclContext *Val) {
  return ::clang::cast_convert_decl_context<ToTy>::doit(Val);
}
2598};

2600template<class ToTy>
2601struct cast_convert_val<ToTy, ::clang::DeclContext*, ::clang::DeclContext*> {
static ToTy *doit(::clang::DeclContext *Val) {
  return ::clang::cast_convert_decl_context<ToTy>::doit(Val);
}
2605};

2607/// Implement cast_convert_val for Decl -> DeclContext conversions.
2608template<class FromTy>
2609struct cast_convert_val< ::clang::DeclContext, FromTy, FromTy> {
static ::clang::DeclContext &doit(const FromTy &Val) {
  return *FromTy::castToDeclContext(&Val);
}
2613};

2615template<class FromTy>
2616struct cast_convert_val< ::clang::DeclContext, FromTy*, FromTy*> {
static ::clang::DeclContext *doit(const FromTy *Val) {
  return FromTy::castToDeclContext(Val);
}
2620};

2622template<class FromTy>
2623struct cast_convert_val< const ::clang::DeclContext, FromTy, FromTy> {
static const ::clang::DeclContext &doit(const FromTy &Val) {
  return *FromTy::castToDeclContext(&Val);
}
2627};

2629template<class FromTy>
2630struct cast_convert_val< const ::clang::DeclContext, FromTy*, FromTy*> {
static const ::clang::DeclContext *doit(const FromTy *Val) {
  return FromTy::castToDeclContext(Val);
}
2634};

2636} // namespace llvm

2638#endif // LLVM_CLANG_AST_DECLBASE_H

←

/usr/src/gnu/usr.bin/clang/liblldbPluginExpressionParser/../../../llvm/llvm/include/llvm/Support/Error.h

1//===- llvm/Support/Error.h - Recoverable error handling --------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file defines an API used to report recoverable errors.
10//
11//===----------------------------------------------------------------------===//
12 
13#ifndef LLVM_SUPPORT_ERROR_H
14#define LLVM_SUPPORT_ERROR_H
15 
16#include "llvm-c/Error.h"
17#include "llvm/ADT/STLExtras.h"
18#include "llvm/ADT/SmallVector.h"
19#include "llvm/ADT/StringExtras.h"
20#include "llvm/ADT/Twine.h"
21#include "llvm/Config/abi-breaking.h"
22#include "llvm/Support/AlignOf.h"
23#include "llvm/Support/Compiler.h"
24#include "llvm/Support/Debug.h"
25#include "llvm/Support/ErrorHandling.h"
26#include "llvm/Support/ErrorOr.h"
27#include "llvm/Support/Format.h"
28#include "llvm/Support/raw_ostream.h"
29#include <algorithm>
30#include <cassert>
31#include <cstdint>
32#include <cstdlib>
33#include <functional>
34#include <memory>
35#include <new>
36#include <string>
37#include <system_error>
38#include <type_traits>
39#include <utility>
40#include <vector>
41 
42namespace llvm {
43 
44class ErrorSuccess;
45 
46/// Base class for error info classes. Do not extend this directly: Extend
47/// the ErrorInfo template subclass instead.
48class ErrorInfoBase {
49public:
50  virtual ~ErrorInfoBase() = default;
51 
52  /// Print an error message to an output stream.
53  virtual void log(raw_ostream &OS) const = 0;
54 
55  /// Return the error message as a string.
56  virtual std::string message() const {
57    std::string Msg;
58    raw_string_ostream OS(Msg);
59    log(OS);
60    return OS.str();
61  }
62 
63  /// Convert this error to a std::error_code.
64  ///
65  /// This is a temporary crutch to enable interaction with code still
66  /// using std::error_code. It will be removed in the future.
67  virtual std::error_code convertToErrorCode() const = 0;
68 
69  // Returns the class ID for this type.
70  static const void *classID() { return &ID; }
71 
72  // Returns the class ID for the dynamic type of this ErrorInfoBase instance.
73  virtual const void *dynamicClassID() const = 0;
74 
75  // Check whether this instance is a subclass of the class identified by
76  // ClassID.
77  virtual bool isA(const void *const ClassID) const {
78    return ClassID == classID();
79  }
80 
81  // Check whether this instance is a subclass of ErrorInfoT.
82  template <typename ErrorInfoT> bool isA() const {
83    return isA(ErrorInfoT::classID());
84  }
85 
86private:
87  virtual void anchor();
88 
89  static char ID;
90};
91 
92/// Lightweight error class with error context and mandatory checking.
93///
94/// Instances of this class wrap a ErrorInfoBase pointer. Failure states
95/// are represented by setting the pointer to a ErrorInfoBase subclass
96/// instance containing information describing the failure. Success is
97/// represented by a null pointer value.
98///
99/// Instances of Error also contains a 'Checked' flag, which must be set
100/// before the destructor is called, otherwise the destructor will trigger a
101/// runtime error. This enforces at runtime the requirement that all Error
102/// instances be checked or returned to the caller.
103///
104/// There are two ways to set the checked flag, depending on what state the
105/// Error instance is in. For Error instances indicating success, it
106/// is sufficient to invoke the boolean conversion operator. E.g.:
107///
108///   @code{.cpp}
109///   Error foo(<...>);
110///
111///   if (auto E = foo(<...>))
112///     return E; // <- Return E if it is in the error state.
113///   // We have verified that E was in the success state. It can now be safely
114///   // destroyed.
115///   @endcode
116///
117/// A success value *can not* be dropped. For example, just calling 'foo(<...>)'
118/// without testing the return value will raise a runtime error, even if foo
119/// returns success.
120///
121/// For Error instances representing failure, you must use either the
122/// handleErrors or handleAllErrors function with a typed handler. E.g.:
123///
124///   @code{.cpp}
125///   class MyErrorInfo : public ErrorInfo<MyErrorInfo> {
126///     // Custom error info.
127///   };
128///
129///   Error foo(<...>) { return make_error<MyErrorInfo>(...); }
130///
131///   auto E = foo(<...>); // <- foo returns failure with MyErrorInfo.
132///   auto NewE =
133///     handleErrors(E,
134///       [](const MyErrorInfo &M) {
135///         // Deal with the error.
136///       },
137///       [](std::unique_ptr<OtherError> M) -> Error {
138///         if (canHandle(*M)) {
139///           // handle error.
140///           return Error::success();
141///         }
142///         // Couldn't handle this error instance. Pass it up the stack.
143///         return Error(std::move(M));
144///       );
145///   // Note - we must check or return NewE in case any of the handlers
146///   // returned a new error.
147///   @endcode
148///
149/// The handleAllErrors function is identical to handleErrors, except
150/// that it has a void return type, and requires all errors to be handled and
151/// no new errors be returned. It prevents errors (assuming they can all be
152/// handled) from having to be bubbled all the way to the top-level.
153///
154/// *All* Error instances must be checked before destruction, even if
155/// they're moved-assigned or constructed from Success values that have already
156/// been checked. This enforces checking through all levels of the call stack.
157class LLVM_NODISCARD[[clang::warn_unused_result]] Error {
158  // ErrorList needs to be able to yank ErrorInfoBase pointers out of Errors
159  // to add to the error list. It can't rely on handleErrors for this, since
160  // handleErrors does not support ErrorList handlers.
161  friend class ErrorList;
162 
163  // handleErrors needs to be able to set the Checked flag.
164  template <typename... HandlerTs>
165  friend Error handleErrors(Error E, HandlerTs &&... Handlers);
166 
167  // Expected<T> needs to be able to steal the payload when constructed from an
168  // error.
169  template <typename T> friend class Expected;
170 
171  // wrap needs to be able to steal the payload.
172  friend LLVMErrorRef wrap(Error);
173 
174protected:
175  /// Create a success value. Prefer using 'Error::success()' for readability
176  Error() {
177    setPtr(nullptr);
178    setChecked(false);
179  }
180 
181public:
182  /// Create a success value.
183  static ErrorSuccess success();
184 
185  // Errors are not copy-constructable.
186  Error(const Error &Other) = delete;
187 
188  /// Move-construct an error value. The newly constructed error is considered
189  /// unchecked, even if the source error had been checked. The original error
190  /// becomes a checked Success value, regardless of its original state.
191  Error(Error &&Other) {
192    setChecked(true);
193    *this = std::move(Other);
194  }
195 
196  /// Create an error value. Prefer using the 'make_error' function, but
197  /// this constructor can be useful when "re-throwing" errors from handlers.
198  Error(std::unique_ptr<ErrorInfoBase> Payload) {
199    setPtr(Payload.release());
200    setChecked(false);
201  }
202 
203  // Errors are not copy-assignable.
204  Error &operator=(const Error &Other) = delete;
205 
206  /// Move-assign an error value. The current error must represent success, you
207  /// you cannot overwrite an unhandled error. The current error is then
208  /// considered unchecked. The source error becomes a checked success value,
209  /// regardless of its original state.
210  Error &operator=(Error &&Other) {
211    // Don't allow overwriting of unchecked values.
212    assertIsChecked();
213    setPtr(Other.getPtr());
214 
215    // This Error is unchecked, even if the source error was checked.
216    setChecked(false);
217 
218    // Null out Other's payload and set its checked bit.
219    Other.setPtr(nullptr);
220    Other.setChecked(true);
221 
222    return *this;
223  }
224 
225  /// Destroy a Error. Fails with a call to abort() if the error is
226  /// unchecked.
227  ~Error() {
228    assertIsChecked();
229    delete getPtr();
230  }
231 
232  /// Bool conversion. Returns true if this Error is in a failure state,
233  /// and false if it is in an accept state. If the error is in a Success state
234  /// it will be considered checked.
235  explicit operator bool() {
236    setChecked(getPtr() == nullptr);
237    return getPtr() != nullptr;
238  }
239 
240  /// Check whether one error is a subclass of another.
241  template <typename ErrT> bool isA() const {
242    return getPtr() && getPtr()->isA(ErrT::classID());
243  }
244 
245  /// Returns the dynamic class id of this error, or null if this is a success
246  /// value.
247  const void* dynamicClassID() const {
248    if (!getPtr())
249      return nullptr;
250    return getPtr()->dynamicClassID();
251  }
252 
253private:
254#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
255  // assertIsChecked() happens very frequently, but under normal circumstances
256  // is supposed to be a no-op.  So we want it to be inlined, but having a bunch
257  // of debug prints can cause the function to be too large for inlining.  So
258  // it's important that we define this function out of line so that it can't be
259  // inlined.
260  LLVM_ATTRIBUTE_NORETURN__attribute__((noreturn))
261  void fatalUncheckedError() const;
262#endif
263 
264  void assertIsChecked() {
265#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
266    if (LLVM_UNLIKELY(!getChecked() || getPtr())__builtin_expect((bool)(!getChecked() || getPtr()), false))
267      fatalUncheckedError();
268#endif
269  }
270 
271  ErrorInfoBase *getPtr() const {
272#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
273    return reinterpret_cast<ErrorInfoBase*>(
274             reinterpret_cast<uintptr_t>(Payload) &
275             ~static_cast<uintptr_t>(0x1));
276#else
277    return Payload;
278#endif
279  }
280 
281  void setPtr(ErrorInfoBase *EI) {
282#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
283    Payload = reinterpret_cast<ErrorInfoBase*>(
284                (reinterpret_cast<uintptr_t>(EI) &
285                 ~static_cast<uintptr_t>(0x1)) |
286                (reinterpret_cast<uintptr_t>(Payload) & 0x1));
287#else
288    Payload = EI;
289#endif
290  }
291 
292  bool getChecked() const {
293#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
294    return (reinterpret_cast<uintptr_t>(Payload) & 0x1) == 0;
295#else
296    return true;
297#endif
298  }
299 
300  void setChecked(bool V) {
301#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
302    Payload = reinterpret_cast<ErrorInfoBase*>(
303                (reinterpret_cast<uintptr_t>(Payload) &
304                  ~static_cast<uintptr_t>(0x1)) |
305                  (V ? 0 : 1));
306#endif
307  }
308 
309  std::unique_ptr<ErrorInfoBase> takePayload() {
310    std::unique_ptr<ErrorInfoBase> Tmp(getPtr());
311    setPtr(nullptr);
312    setChecked(true);
313    return Tmp;
314  }
315 
316  friend raw_ostream &operator<<(raw_ostream &OS, const Error &E) {
317    if (auto P = E.getPtr())
318      P->log(OS);
319    else
320      OS << "success";
321    return OS;
322  }
323 
324  ErrorInfoBase *Payload = nullptr;
325};
326 
327/// Subclass of Error for the sole purpose of identifying the success path in
328/// the type system. This allows to catch invalid conversion to Expected<T> at
329/// compile time.
330class ErrorSuccess final : public Error {};
331 
332inline ErrorSuccess Error::success() { return ErrorSuccess(); }
333 
334/// Make a Error instance representing failure using the given error info
335/// type.
336template <typename ErrT, typename... ArgTs> Error make_error(ArgTs &&... Args) {
337  return Error(std::make_unique<ErrT>(std::forward<ArgTs>(Args)...));
338}
339 
340/// Base class for user error types. Users should declare their error types
341/// like:
342///
343/// class MyError : public ErrorInfo<MyError> {
344///   ....
345/// };
346///
347/// This class provides an implementation of the ErrorInfoBase::kind
348/// method, which is used by the Error RTTI system.
349template <typename ThisErrT, typename ParentErrT = ErrorInfoBase>
350class ErrorInfo : public ParentErrT {
351public:
352  using ParentErrT::ParentErrT; // inherit constructors
353 
354  static const void *classID() { return &ThisErrT::ID; }
355 
356  const void *dynamicClassID() const override { return &ThisErrT::ID; }
357 
358  bool isA(const void *const ClassID) const override {
359    return ClassID == classID() || ParentErrT::isA(ClassID);
360  }
361};
362 
363/// Special ErrorInfo subclass representing a list of ErrorInfos.
364/// Instances of this class are constructed by joinError.
365class ErrorList final : public ErrorInfo<ErrorList> {
366  // handleErrors needs to be able to iterate the payload list of an
367  // ErrorList.
368  template <typename... HandlerTs>
369  friend Error handleErrors(Error E, HandlerTs &&... Handlers);
370 
371  // joinErrors is implemented in terms of join.
372  friend Error joinErrors(Error, Error);
373 
374public:
375  void log(raw_ostream &OS) const override {
376    OS << "Multiple errors:\n";
377    for (auto &ErrPayload : Payloads) {
378      ErrPayload->log(OS);
379      OS << "\n";
380    }
381  }
382 
383  std::error_code convertToErrorCode() const override;
384 
385  // Used by ErrorInfo::classID.
386  static char ID;
387 
388private:
389  ErrorList(std::unique_ptr<ErrorInfoBase> Payload1,
390            std::unique_ptr<ErrorInfoBase> Payload2) {
391    assert(!Payload1->isA<ErrorList>() && !Payload2->isA<ErrorList>() &&((void)0)
392           "ErrorList constructor payloads should be singleton errors")((void)0);
393    Payloads.push_back(std::move(Payload1));
394    Payloads.push_back(std::move(Payload2));
395  }
396 
397  static Error join(Error E1, Error E2) {
398    if (!E1)
399      return E2;
400    if (!E2)
401      return E1;
402    if (E1.isA<ErrorList>()) {
403      auto &E1List = static_cast<ErrorList &>(*E1.getPtr());
404      if (E2.isA<ErrorList>()) {
405        auto E2Payload = E2.takePayload();
406        auto &E2List = static_cast<ErrorList &>(*E2Payload);
407        for (auto &Payload : E2List.Payloads)
408          E1List.Payloads.push_back(std::move(Payload));
409      } else
410        E1List.Payloads.push_back(E2.takePayload());
411 
412      return E1;
413    }
414    if (E2.isA<ErrorList>()) {
415      auto &E2List = static_cast<ErrorList &>(*E2.getPtr());
416      E2List.Payloads.insert(E2List.Payloads.begin(), E1.takePayload());
417      return E2;
418    }
419    return Error(std::unique_ptr<ErrorList>(
420        new ErrorList(E1.takePayload(), E2.takePayload())));
421  }
422 
423  std::vector<std::unique_ptr<ErrorInfoBase>> Payloads;
424};
425 
426/// Concatenate errors. The resulting Error is unchecked, and contains the
427/// ErrorInfo(s), if any, contained in E1, followed by the
428/// ErrorInfo(s), if any, contained in E2.
429inline Error joinErrors(Error E1, Error E2) {
430  return ErrorList::join(std::move(E1), std::move(E2));
431}
432 
433/// Tagged union holding either a T or a Error.
434///
435/// This class parallels ErrorOr, but replaces error_code with Error. Since
436/// Error cannot be copied, this class replaces getError() with
437/// takeError(). It also adds an bool errorIsA<ErrT>() method for testing the
438/// error class type.
439///
440/// Example usage of 'Expected<T>' as a function return type:
441///
442///   @code{.cpp}
443///     Expected<int> myDivide(int A, int B) {
444///       if (B == 0) {
445///         // return an Error
446///         return createStringError(inconvertibleErrorCode(),
447///                                  "B must not be zero!");
448///       }
449///       // return an integer
450///       return A / B;
451///     }
452///   @endcode
453///
454///   Checking the results of to a function returning 'Expected<T>':
455///   @code{.cpp}
456///     if (auto E = Result.takeError()) {
457///       // We must consume the error. Typically one of:
458///       // - return the error to our caller
459///       // - toString(), when logging
460///       // - consumeError(), to silently swallow the error
461///       // - handleErrors(), to distinguish error types
462///       errs() << "Problem with division " << toString(std::move(E)) << "\n";
463///       return;
464///     }
465///     // use the result
466///     outs() << "The answer is " << *Result << "\n";
467///   @endcode
468///
469///  For unit-testing a function returning an 'Expceted<T>', see the
470///  'EXPECT_THAT_EXPECTED' macros in llvm/Testing/Support/Error.h
471 
472template <class T> class LLVM_NODISCARD[[clang::warn_unused_result]] Expected {
473  template <class T1> friend class ExpectedAsOutParameter;
474  template <class OtherT> friend class Expected;
475 
476  static constexpr bool isRef = std::is_reference<T>::value;
477 
478  using wrap = std::reference_wrapper<std::remove_reference_t<T>>;
479 
480  using error_type = std::unique_ptr<ErrorInfoBase>;
481 
482public:
483  using storage_type = std::conditional_t<isRef, wrap, T>;
484  using value_type = T;
485 
486private:
487  using reference = std::remove_reference_t<T> &;
488  using const_reference = const std::remove_reference_t<T> &;
489  using pointer = std::remove_reference_t<T> *;
490  using const_pointer = const std::remove_reference_t<T> *;
491 
492public:
493  /// Create an Expected<T> error value from the given Error.
494  Expected(Error Err)
495      : HasError(true)
496#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
497        // Expected is unchecked upon construction in Debug builds.
498        , Unchecked(true)
499#endif
500  {
501    assert(Err && "Cannot create Expected<T> from Error success value.")((void)0);
502    new (getErrorStorage()) error_type(Err.takePayload());
503  }
504 
505  /// Forbid to convert from Error::success() implicitly, this avoids having
506  /// Expected<T> foo() { return Error::success(); } which compiles otherwise
507  /// but triggers the assertion above.
508  Expected(ErrorSuccess) = delete;
509 
510  /// Create an Expected<T> success value from the given OtherT value, which
511  /// must be convertible to T.
512  template <typename OtherT>
513  Expected(OtherT &&Val,
514           std::enable_if_t<std::is_convertible<OtherT, T>::value> * = nullptr)
515      : HasError(false)
516#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
517        // Expected is unchecked upon construction in Debug builds.
518        ,
519        Unchecked(true)
520#endif
521  {
522    new (getStorage()) storage_type(std::forward<OtherT>(Val));
523  }
524 
525  /// Move construct an Expected<T> value.
526  Expected(Expected &&Other) { moveConstruct(std::move(Other)); }
527 
528  /// Move construct an Expected<T> value from an Expected<OtherT>, where OtherT
529  /// must be convertible to T.
530  template <class OtherT>
531  Expected(
532      Expected<OtherT> &&Other,
533      std::enable_if_t<std::is_convertible<OtherT, T>::value> * = nullptr) {
534    moveConstruct(std::move(Other));
535  }
536 
537  /// Move construct an Expected<T> value from an Expected<OtherT>, where OtherT
538  /// isn't convertible to T.
539  template <class OtherT>
540  explicit Expected(
541      Expected<OtherT> &&Other,
542      std::enable_if_t<!std::is_convertible<OtherT, T>::value> * = nullptr) {
543    moveConstruct(std::move(Other));
544  }
545 
546  /// Move-assign from another Expected<T>.
547  Expected &operator=(Expected &&Other) {
548    moveAssign(std::move(Other));
549    return *this;
550  }
551 
552  /// Destroy an Expected<T>.
553  ~Expected() {
554    assertIsChecked();
555    if (!HasError)
556      getStorage()->~storage_type();
557    else
558      getErrorStorage()->~error_type();
559  }
560 
561  /// Return false if there is an error.
562  explicit operator bool() {
563#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
564    Unchecked = HasError;
565#endif
566    return !HasError;
27
←
Assuming field 'HasError' is false, which participates in a condition later→
28
←
Returning the value 1, which participates in a condition later→
567  }
568 
569  /// Returns a reference to the stored T value.
570  reference get() {
571    assertIsChecked();
572    return *getStorage();
573  }
574 
575  /// Returns a const reference to the stored T value.
576  const_reference get() const {
577    assertIsChecked();
578    return const_cast<Expected<T> *>(this)->get();
579  }
580 
581  /// Check that this Expected<T> is an error of type ErrT.
582  template <typename ErrT> bool errorIsA() const {
583    return HasError && (*getErrorStorage())->template isA<ErrT>();
584  }
585 
586  /// Take ownership of the stored error.
587  /// After calling this the Expected<T> is in an indeterminate state that can
588  /// only be safely destructed. No further calls (beside the destructor) should
589  /// be made on the Expected<T> value.
590  Error takeError() {
591#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
592    Unchecked = false;
593#endif
594    return HasError ? Error(std::move(*getErrorStorage())) : Error::success();
595  }
596 
597  /// Returns a pointer to the stored T value.
598  pointer operator->() {
599    assertIsChecked();
600    return toPointer(getStorage());
601  }
602 
603  /// Returns a const pointer to the stored T value.
604  const_pointer operator->() const {
605    assertIsChecked();
606    return toPointer(getStorage());
607  }
608 
609  /// Returns a reference to the stored T value.
610  reference operator*() {
611    assertIsChecked();
612    return *getStorage();
613  }
614 
615  /// Returns a const reference to the stored T value.
616  const_reference operator*() const {
617    assertIsChecked();
618    return *getStorage();
619  }
620 
621private:
622  template <class T1>
623  static bool compareThisIfSameType(const T1 &a, const T1 &b) {
624    return &a == &b;
625  }
626 
627  template <class T1, class T2>
628  static bool compareThisIfSameType(const T1 &, const T2 &) {
629    return false;
630  }
631 
632  template <class OtherT> void moveConstruct(Expected<OtherT> &&Other) {
633    HasError = Other.HasError;
634#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
635    Unchecked = true;
636    Other.Unchecked = false;
637#endif
638 
639    if (!HasError)
640      new (getStorage()) storage_type(std::move(*Other.getStorage()));
641    else
642      new (getErrorStorage()) error_type(std::move(*Other.getErrorStorage()));
643  }
644 
645  template <class OtherT> void moveAssign(Expected<OtherT> &&Other) {
646    assertIsChecked();
647 
648    if (compareThisIfSameType(*this, Other))
649      return;
650 
651    this->~Expected();
652    new (this) Expected(std::move(Other));
653  }
654 
655  pointer toPointer(pointer Val) { return Val; }
656 
657  const_pointer toPointer(const_pointer Val) const { return Val; }
658 
659  pointer toPointer(wrap *Val) { return &Val->get(); }
660 
661  const_pointer toPointer(const wrap *Val) const { return &Val->get(); }
662 
663  storage_type *getStorage() {
664    assert(!HasError && "Cannot get value when an error exists!")((void)0);
665    return reinterpret_cast<storage_type *>(&TStorage);
666  }
667 
668  const storage_type *getStorage() const {
669    assert(!HasError && "Cannot get value when an error exists!")((void)0);
670    return reinterpret_cast<const storage_type *>(&TStorage);
671  }
672 
673  error_type *getErrorStorage() {
674    assert(HasError && "Cannot get error when a value exists!")((void)0);
675    return reinterpret_cast<error_type *>(&ErrorStorage);
676  }
677 
678  const error_type *getErrorStorage() const {
679    assert(HasError && "Cannot get error when a value exists!")((void)0);
680    return reinterpret_cast<const error_type *>(&ErrorStorage);
681  }
682 
683  // Used by ExpectedAsOutParameter to reset the checked flag.
684  void setUnchecked() {
685#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
686    Unchecked = true;
687#endif
688  }
689 
690#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
691  LLVM_ATTRIBUTE_NORETURN__attribute__((noreturn))
692  LLVM_ATTRIBUTE_NOINLINE__attribute__((noinline))
693  void fatalUncheckedExpected() const {
694    dbgs() << "Expected<T> must be checked before access or destruction.\n";
695    if (HasError) {
696      dbgs() << "Unchecked Expected<T> contained error:\n";
697      (*getErrorStorage())->log(dbgs());
698    } else
699      dbgs() << "Expected<T> value was in success state. (Note: Expected<T> "
700                "values in success mode must still be checked prior to being "
701                "destroyed).\n";
702    abort();
703  }
704#endif
705 
706  void assertIsChecked() const {
707#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
708    if (LLVM_UNLIKELY(Unchecked)__builtin_expect((bool)(Unchecked), false))
709      fatalUncheckedExpected();
710#endif
711  }
712 
713  union {
714    AlignedCharArrayUnion<storage_type> TStorage;
715    AlignedCharArrayUnion<error_type> ErrorStorage;
716  };
717  bool HasError : 1;
718#if LLVM_ENABLE_ABI_BREAKING_CHECKS0
719  bool Unchecked : 1;
720#endif
721};
722 
723/// Report a serious error, calling any installed error handler. See
724/// ErrorHandling.h.
725LLVM_ATTRIBUTE_NORETURN__attribute__((noreturn)) void report_fatal_error(Error Err,
726                                                bool gen_crash_diag = true);
727 
728/// Report a fatal error if Err is a failure value.
729///
730/// This function can be used to wrap calls to fallible functions ONLY when it
731/// is known that the Error will always be a success value. E.g.
732///
733///   @code{.cpp}
734///   // foo only attempts the fallible operation if DoFallibleOperation is
735///   // true. If DoFallibleOperation is false then foo always returns
736///   // Error::success().
737///   Error foo(bool DoFallibleOperation);
738///
739///   cantFail(foo(false));
740///   @endcode
741inline void cantFail(Error Err, const char *Msg = nullptr) {
742  if (Err) {
743    if (!Msg)
744      Msg = "Failure value returned from cantFail wrapped call";
745#ifndef NDEBUG1
746    std::string Str;
747    raw_string_ostream OS(Str);
748    OS << Msg << "\n" << Err;
749    Msg = OS.str().c_str();
750#endif
751    llvm_unreachable(Msg)__builtin_unreachable();
752  }
753}
754 
755/// Report a fatal error if ValOrErr is a failure value, otherwise unwraps and
756/// returns the contained value.
757///
758/// This function can be used to wrap calls to fallible functions ONLY when it
759/// is known that the Error will always be a success value. E.g.
760///
761///   @code{.cpp}
762///   // foo only attempts the fallible operation if DoFallibleOperation is
763///   // true. If DoFallibleOperation is false then foo always returns an int.
764///   Expected<int> foo(bool DoFallibleOperation);
765///
766///   int X = cantFail(foo(false));
767///   @endcode
768template <typename T>
769T cantFail(Expected<T> ValOrErr, const char *Msg = nullptr) {
770  if (ValOrErr)
771    return std::move(*ValOrErr);
772  else {
773    if (!Msg)
774      Msg = "Failure value returned from cantFail wrapped call";
775#ifndef NDEBUG1
776    std::string Str;
777    raw_string_ostream OS(Str);
778    auto E = ValOrErr.takeError();
779    OS << Msg << "\n" << E;
780    Msg = OS.str().c_str();
781#endif
782    llvm_unreachable(Msg)__builtin_unreachable();
783  }
784}
785 
786/// Report a fatal error if ValOrErr is a failure value, otherwise unwraps and
787/// returns the contained reference.
788///
789/// This function can be used to wrap calls to fallible functions ONLY when it
790/// is known that the Error will always be a success value. E.g.
791///
792///   @code{.cpp}
793///   // foo only attempts the fallible operation if DoFallibleOperation is
794///   // true. If DoFallibleOperation is false then foo always returns a Bar&.
795///   Expected<Bar&> foo(bool DoFallibleOperation);
796///
797///   Bar &X = cantFail(foo(false));
798///   @endcode
799template <typename T>
800T& cantFail(Expected<T&> ValOrErr, const char *Msg = nullptr) {
801  if (ValOrErr)
802    return *ValOrErr;
803  else {
804    if (!Msg)
805      Msg = "Failure value returned from cantFail wrapped call";
806#ifndef NDEBUG1
807    std::string Str;
808    raw_string_ostream OS(Str);
809    auto E = ValOrErr.takeError();
810    OS << Msg << "\n" << E;
811    Msg = OS.str().c_str();
812#endif
813    llvm_unreachable(Msg)__builtin_unreachable();
814  }
815}
816 
817/// Helper for testing applicability of, and applying, handlers for
818/// ErrorInfo types.
819template <typename HandlerT>
820class ErrorHandlerTraits
821    : public ErrorHandlerTraits<decltype(
822          &std::remove_reference<HandlerT>::type::operator())> {};
823 
824// Specialization functions of the form 'Error (const ErrT&)'.
825template <typename ErrT> class ErrorHandlerTraits<Error (&)(ErrT &)> {
826public:
827  static bool appliesTo(const ErrorInfoBase &E) {
828    return E.template isA<ErrT>();
829  }
830 
831  template <typename HandlerT>
832  static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
833    assert(appliesTo(*E) && "Applying incorrect handler")((void)0);
834    return H(static_cast<ErrT &>(*E));
835  }
836};
837 
838// Specialization functions of the form 'void (const ErrT&)'.
839template <typename ErrT> class ErrorHandlerTraits<void (&)(ErrT &)> {
840public:
841  static bool appliesTo(const ErrorInfoBase &E) {
842    return E.template isA<ErrT>();
843  }
844 
845  template <typename HandlerT>
846  static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
847    assert(appliesTo(*E) && "Applying incorrect handler")((void)0);
848    H(static_cast<ErrT &>(*E));
849    return Error::success();
850  }
851};
852 
853/// Specialization for functions of the form 'Error (std::unique_ptr<ErrT>)'.
854template <typename ErrT>
855class ErrorHandlerTraits<Error (&)(std::unique_ptr<ErrT>)> {
856public:
857  static bool appliesTo(const ErrorInfoBase &E) {
858    return E.template isA<ErrT>();
859  }
860 
861  template <typename HandlerT>
862  static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
863    assert(appliesTo(*E) && "Applying incorrect handler")((void)0);
864    std::unique_ptr<ErrT> SubE(static_cast<ErrT *>(E.release()));
865    return H(std::move(SubE));
866  }
867};
868 
869/// Specialization for functions of the form 'void (std::unique_ptr<ErrT>)'.
870template <typename ErrT>
871class ErrorHandlerTraits<void (&)(std::unique_ptr<ErrT>)> {
872public:
873  static bool appliesTo(const ErrorInfoBase &E) {
874    return E.template isA<ErrT>();
875  }
876 
877  template <typename HandlerT>
878  static Error apply(HandlerT &&H, std::unique_ptr<ErrorInfoBase> E) {
879    assert(appliesTo(*E) && "Applying incorrect handler")((void)0);
880    std::unique_ptr<ErrT> SubE(static_cast<ErrT *>(E.release()));
881    H(std::move(SubE));
882    return Error::success();
883  }
884};
885 
886// Specialization for member functions of the form 'RetT (const ErrT&)'.
887template <typename C, typename RetT, typename ErrT>
888class ErrorHandlerTraits<RetT (C::*)(ErrT &)>
889    : public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
890 
891// Specialization for member functions of the form 'RetT (const ErrT&) const'.
892template <typename C, typename RetT, typename ErrT>
893class ErrorHandlerTraits<RetT (C::*)(ErrT &) const>
894    : public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
895 
896// Specialization for member functions of the form 'RetT (const ErrT&)'.
897template <typename C, typename RetT, typename ErrT>
898class ErrorHandlerTraits<RetT (C::*)(const ErrT &)>
899    : public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
900 
901// Specialization for member functions of the form 'RetT (const ErrT&) const'.
902template <typename C, typename RetT, typename ErrT>
903class ErrorHandlerTraits<RetT (C::*)(const ErrT &) const>
904    : public ErrorHandlerTraits<RetT (&)(ErrT &)> {};
905 
906/// Specialization for member functions of the form
907/// 'RetT (std::unique_ptr<ErrT>)'.
908template <typename C, typename RetT, typename ErrT>
909class ErrorHandlerTraits<RetT (C::*)(std::unique_ptr<ErrT>)>
910    : public ErrorHandlerTraits<RetT (&)(std::unique_ptr<ErrT>)> {};
911 
912/// Specialization for member functions of the form
913/// 'RetT (std::unique_ptr<ErrT>) const'.
914template <typename C, typename RetT, typename ErrT>
915class ErrorHandlerTraits<RetT (C::*)(std::unique_ptr<ErrT>) const>
916    : public ErrorHandlerTraits<RetT (&)(std::unique_ptr<ErrT>)> {};
917 
918inline Error handleErrorImpl(std::unique_ptr<ErrorInfoBase> Payload) {
919  return Error(std::move(Payload));
920}
921 
922template <typename HandlerT, typename... HandlerTs>
923Error handleErrorImpl(std::unique_ptr<ErrorInfoBase> Payload,
924                      HandlerT &&Handler, HandlerTs &&... Handlers) {
925  if (ErrorHandlerTraits<HandlerT>::appliesTo(*Payload))
926    return ErrorHandlerTraits<HandlerT>::apply(std::forward<HandlerT>(Handler),
927                                               std::move(Payload));
928  return handleErrorImpl(std::move(Payload),
929                         std::forward<HandlerTs>(Handlers)...);
930}
931 
932/// Pass the ErrorInfo(s) contained in E to their respective handlers. Any
933/// unhandled errors (or Errors returned by handlers) are re-concatenated and
934/// returned.
935/// Because this function returns an error, its result must also be checked
936/// or returned. If you intend to handle all errors use handleAllErrors
937/// (which returns void, and will abort() on unhandled errors) instead.
938template <typename... HandlerTs>
939Error handleErrors(Error E, HandlerTs &&... Hs) {
940  if (!E)
941    return Error::success();
942 
943  std::unique_ptr<ErrorInfoBase> Payload = E.takePayload();
944 
945  if (Payload->isA<ErrorList>()) {
946    ErrorList &List = static_cast<ErrorList &>(*Payload);
947    Error R;
948    for (auto &P : List.Payloads)
949      R = ErrorList::join(
950          std::move(R),
951          handleErrorImpl(std::move(P), std::forward<HandlerTs>(Hs)...));
952    return R;
953  }
954 
955  return handleErrorImpl(std::move(Payload), std::forward<HandlerTs>(Hs)...);
956}
957 
958/// Behaves the same as handleErrors, except that by contract all errors
959/// *must* be handled by the given handlers (i.e. there must be no remaining
960/// errors after running the handlers, or llvm_unreachable is called).
961template <typename... HandlerTs>
962void handleAllErrors(Error E, HandlerTs &&... Handlers) {
963  cantFail(handleErrors(std::move(E), std::forward<HandlerTs>(Handlers)...));
964}
965 
966/// Check that E is a non-error, then drop it.
967/// If E is an error, llvm_unreachable will be called.
968inline void handleAllErrors(Error E) {
969  cantFail(std::move(E));
970}
971 
972/// Handle any errors (if present) in an Expected<T>, then try a recovery path.
973///
974/// If the incoming value is a success value it is returned unmodified. If it
975/// is a failure value then it the contained error is passed to handleErrors.
976/// If handleErrors is able to handle the error then the RecoveryPath functor
977/// is called to supply the final result. If handleErrors is not able to
978/// handle all errors then the unhandled errors are returned.
979///
980/// This utility enables the follow pattern:
981///
982///   @code{.cpp}
983///   enum FooStrategy { Aggressive, Conservative };
984///   Expected<Foo> foo(FooStrategy S);
985///
986///   auto ResultOrErr =
987///     handleExpected(
988///       foo(Aggressive),
989///       []() { return foo(Conservative); },
990///       [](AggressiveStrategyError&) {
991///         // Implicitly conusme this - we'll recover by using a conservative
992///         // strategy.
993///       });
994///
995///   @endcode
996template <typename T, typename RecoveryFtor, typename... HandlerTs>
997Expected<T> handleExpected(Expected<T> ValOrErr, RecoveryFtor &&RecoveryPath,
998                           HandlerTs &&... Handlers) {
999  if (ValOrErr)
1000    return ValOrErr;
1001 
1002  if (auto Err = handleErrors(ValOrErr.takeError(),
1003                              std::forward<HandlerTs>(Handlers)...))
1004    return std::move(Err);
1005 
1006  return RecoveryPath();
1007}
1008 
1009/// Log all errors (if any) in E to OS. If there are any errors, ErrorBanner
1010/// will be printed before the first one is logged. A newline will be printed
1011/// after each error.
1012///
1013/// This function is compatible with the helpers from Support/WithColor.h. You
1014/// can pass any of them as the OS. Please consider using them instead of
1015/// including 'error: ' in the ErrorBanner.
1016///
1017/// This is useful in the base level of your program to allow clean termination
1018/// (allowing clean deallocation of resources, etc.), while reporting error
1019/// information to the user.
1020void logAllUnhandledErrors(Error E, raw_ostream &OS, Twine ErrorBanner = {});
1021 
1022/// Write all error messages (if any) in E to a string. The newline character
1023/// is used to separate error messages.
1024inline std::string toString(Error E) {
1025  SmallVector<std::string, 2> Errors;
1026  handleAllErrors(std::move(E), [&Errors](const ErrorInfoBase &EI) {
1027    Errors.push_back(EI.message());
1028  });
1029  return join(Errors.begin(), Errors.end(), "\n");
1030}
1031 
1032/// Consume a Error without doing anything. This method should be used
1033/// only where an error can be considered a reasonable and expected return
1034/// value.
1035///
1036/// Uses of this method are potentially indicative of design problems: If it's
1037/// legitimate to do nothing while processing an "error", the error-producer
1038/// might be more clearly refactored to return an Optional<T>.
1039inline void consumeError(Error Err) {
1040  handleAllErrors(std::move(Err), [](const ErrorInfoBase &) {});
1041}
1042 
1043/// Convert an Expected to an Optional without doing anything. This method
1044/// should be used only where an error can be considered a reasonable and
1045/// expected return value.
1046///
1047/// Uses of this method are potentially indicative of problems: perhaps the
1048/// error should be propagated further, or the error-producer should just
1049/// return an Optional in the first place.
1050template <typename T> Optional<T> expectedToOptional(Expected<T> &&E) {
1051  if (E)
1052    return std::move(*E);
1053  consumeError(E.takeError());
1054  return None;
1055}
1056 
1057/// Helper for converting an Error to a bool.
1058///
1059/// This method returns true if Err is in an error state, or false if it is
1060/// in a success state.  Puts Err in a checked state in both cases (unlike
1061/// Error::operator bool(), which only does this for success states).
1062inline bool errorToBool(Error Err) {
1063  bool IsError = static_cast<bool>(Err);
1064  if (IsError)
1065    consumeError(std::move(Err));
1066  return IsError;
1067}
1068 
1069/// Helper for Errors used as out-parameters.
1070///
1071/// This helper is for use with the Error-as-out-parameter idiom, where an error
1072/// is passed to a function or method by reference, rather than being returned.
1073/// In such cases it is helpful to set the checked bit on entry to the function
1074/// so that the error can be written to (unchecked Errors abort on assignment)
1075/// and clear the checked bit on exit so that clients cannot accidentally forget
1076/// to check the result. This helper performs these actions automatically using
1077/// RAII:
1078///
1079///   @code{.cpp}
1080///   Result foo(Error &Err) {
1081///     ErrorAsOutParameter ErrAsOutParam(&Err); // 'Checked' flag set
1082///     // <body of foo>
1083///     // <- 'Checked' flag auto-cleared when ErrAsOutParam is destructed.
1084///   }
1085///   @endcode
1086///
1087/// ErrorAsOutParameter takes an Error* rather than Error& so that it can be
1088/// used with optional Errors (Error pointers that are allowed to be null). If
1089/// ErrorAsOutParameter took an Error reference, an instance would have to be
1090/// created inside every condition that verified that Error was non-null. By
1091/// taking an Error pointer we can just create one instance at the top of the
1092/// function.
1093class ErrorAsOutParameter {
1094public:
1095  ErrorAsOutParameter(Error *Err) : Err(Err) {
1096    // Raise the checked bit if Err is success.
1097    if (Err)
1098      (void)!!*Err;
1099  }
1100 
1101  ~ErrorAsOutParameter() {
1102    // Clear the checked bit.
1103    if (Err && !*Err)
1104      *Err = Error::success();
1105  }
1106 
1107private:
1108  Error *Err;
1109};
1110 
1111/// Helper for Expected<T>s used as out-parameters.
1112///
1113/// See ErrorAsOutParameter.
1114template <typename T>
1115class ExpectedAsOutParameter {
1116public:
1117  ExpectedAsOutParameter(Expected<T> *ValOrErr)
1118    : ValOrErr(ValOrErr) {
1119    if (ValOrErr)
1120      (void)!!*ValOrErr;
1121  }
1122 
1123  ~ExpectedAsOutParameter() {
1124    if (ValOrErr)
1125      ValOrErr->setUnchecked();
1126  }
1127 
1128private:
1129  Expected<T> *ValOrErr;
1130};
1131 
1132/// This class wraps a std::error_code in a Error.
1133///
1134/// This is useful if you're writing an interface that returns a Error
1135/// (or Expected) and you want to call code that still returns
1136/// std::error_codes.
1137class ECError : public ErrorInfo<ECError> {
1138  friend Error errorCodeToError(std::error_code);
1139 
1140  virtual void anchor() override;
1141 
1142public:
1143  void setErrorCode(std::error_code EC) { this->EC = EC; }
1144  std::error_code convertToErrorCode() const override { return EC; }
1145  void log(raw_ostream &OS) const override { OS << EC.message(); }
1146 
1147  // Used by ErrorInfo::classID.
1148  static char ID;
1149 
1150protected:
1151  ECError() = default;
1152  ECError(std::error_code EC) : EC(EC) {}
1153 
1154  std::error_code EC;
1155};
1156 
1157/// The value returned by this function can be returned from convertToErrorCode
1158/// for Error values where no sensible translation to std::error_code exists.
1159/// It should only be used in this situation, and should never be used where a
1160/// sensible conversion to std::error_code is available, as attempts to convert
1161/// to/from this error will result in a fatal error. (i.e. it is a programmatic
1162///error to try to convert such a value).
1163std::error_code inconvertibleErrorCode();
1164 
1165/// Helper for converting an std::error_code to a Error.
1166Error errorCodeToError(std::error_code EC);
1167 
1168/// Helper for converting an ECError to a std::error_code.
1169///
1170/// This method requires that Err be Error() or an ECError, otherwise it
1171/// will trigger a call to abort().
1172std::error_code errorToErrorCode(Error Err);
1173 
1174/// Convert an ErrorOr<T> to an Expected<T>.
1175template <typename T> Expected<T> errorOrToExpected(ErrorOr<T> &&EO) {
1176  if (auto EC = EO.getError())
1177    return errorCodeToError(EC);
1178  return std::move(*EO);
1179}
1180 
1181/// Convert an Expected<T> to an ErrorOr<T>.
1182template <typename T> ErrorOr<T> expectedToErrorOr(Expected<T> &&E) {
1183  if (auto Err = E.takeError())
1184    return errorToErrorCode(std::move(Err));
1185  return std::move(*E);
1186}
1187 
1188/// This class wraps a string in an Error.
1189///
1190/// StringError is useful in cases where the client is not expected to be able
1191/// to consume the specific error message programmatically (for example, if the
1192/// error message is to be presented to the user).
1193///
1194/// StringError can also be used when additional information is to be printed
1195/// along with a error_code message. Depending on the constructor called, this
1196/// class can either display:
1197///    1. the error_code message (ECError behavior)
1198///    2. a string
1199///    3. the error_code message and a string
1200///
1201/// These behaviors are useful when subtyping is required; for example, when a
1202/// specific library needs an explicit error type. In the example below,
1203/// PDBError is derived from StringError:
1204///
1205///   @code{.cpp}
1206///   Expected<int> foo() {
1207///      return llvm::make_error<PDBError>(pdb_error_code::dia_failed_loading,
1208///                                        "Additional information");
1209///   }
1210///   @endcode
1211///
1212class StringError : public ErrorInfo<StringError> {
1213public:
1214  static char ID;
1215 
1216  // Prints EC + S and converts to EC
1217  StringError(std::error_code EC, const Twine &S = Twine());
1218 
1219  // Prints S and converts to EC
1220  StringError(const Twine &S, std::error_code EC);
1221 
1222  void log(raw_ostream &OS) const override;
1223  std::error_code convertToErrorCode() const override;
1224 
1225  const std::string &getMessage() const { return Msg; }
1226 
1227private:
1228  std::string Msg;
1229  std::error_code EC;
1230  const bool PrintMsgOnly = false;
1231};
1232 
1233/// Create formatted StringError object.
1234template <typename... Ts>
1235inline Error createStringError(std::error_code EC, char const *Fmt,
1236                               const Ts &... Vals) {
1237  std::string Buffer;
1238  raw_string_ostream Stream(Buffer);
1239  Stream << format(Fmt, Vals...);
1240  return make_error<StringError>(Stream.str(), EC);
1241}
1242 
1243Error createStringError(std::error_code EC, char const *Msg);
1244 
1245inline Error createStringError(std::error_code EC, const Twine &S) {
1246  return createStringError(EC, S.str().c_str());
1247}
1248 
1249template <typename... Ts>
1250inline Error createStringError(std::errc EC, char const *Fmt,
1251                               const Ts &... Vals) {
1252  return createStringError(std::make_error_code(EC), Fmt, Vals...);
1253}
1254 
1255/// This class wraps a filename and another Error.
1256///
1257/// In some cases, an error needs to live along a 'source' name, in order to
1258/// show more detailed information to the user.
1259class FileError final : public ErrorInfo<FileError> {
1260 
1261  friend Error createFileError(const Twine &, Error);
1262  friend Error createFileError(const Twine &, size_t, Error);
1263 
1264public:
1265  void log(raw_ostream &OS) const override {
1266    assert(Err && !FileName.empty() && "Trying to log after takeError().")((void)0);
1267    OS << "'" << FileName << "': ";
1268    if (Line.hasValue())
1269      OS << "line " << Line.getValue() << ": ";
1270    Err->log(OS);
1271  }
1272 
1273  StringRef getFileName() { return FileName; }
1274 
1275  Error takeError() { return Error(std::move(Err)); }
1276 
1277  std::error_code convertToErrorCode() const override;
1278 
1279  // Used by ErrorInfo::classID.
1280  static char ID;
1281 
1282private:
1283  FileError(const Twine &F, Optional<size_t> LineNum,
1284            std::unique_ptr<ErrorInfoBase> E) {
1285    assert(E && "Cannot create FileError from Error success value.")((void)0);
1286    assert(!F.isTriviallyEmpty() &&((void)0)
1287           "The file name provided to FileError must not be empty.")((void)0);
1288    FileName = F.str();
1289    Err = std::move(E);
1290    Line = std::move(LineNum);
1291  }
1292 
1293  static Error build(const Twine &F, Optional<size_t> Line, Error E) {
1294    std::unique_ptr<ErrorInfoBase> Payload;
1295    handleAllErrors(std::move(E),
1296                    [&](std::unique_ptr<ErrorInfoBase> EIB) -> Error {
1297                      Payload = std::move(EIB);
1298                      return Error::success();
1299                    });
1300    return Error(
1301        std::unique_ptr<FileError>(new FileError(F, Line, std::move(Payload))));
1302  }
1303 
1304  std::string FileName;
1305  Optional<size_t> Line;
1306  std::unique_ptr<ErrorInfoBase> Err;
1307};
1308 
1309/// Concatenate a source file path and/or name with an Error. The resulting
1310/// Error is unchecked.
1311inline Error createFileError(const Twine &F, Error E) {
1312  return FileError::build(F, Optional<size_t>(), std::move(E));
1313}
1314 
1315/// Concatenate a source file path and/or name with line number and an Error.
1316/// The resulting Error is unchecked.
1317inline Error createFileError(const Twine &F, size_t Line, Error E) {
1318  return FileError::build(F, Optional<size_t>(Line), std::move(E));
1319}
1320 
1321/// Concatenate a source file path and/or name with a std::error_code 
1322/// to form an Error object.
1323inline Error createFileError(const Twine &F, std::error_code EC) {
1324  return createFileError(F, errorCodeToError(EC));
1325}
1326 
1327/// Concatenate a source file path and/or name with line number and
1328/// std::error_code to form an Error object.
1329inline Error createFileError(const Twine &F, size_t Line, std::error_code EC) {
1330  return createFileError(F, Line, errorCodeToError(EC));
1331}
1332 
1333Error createFileError(const Twine &F, ErrorSuccess) = delete;
1334 
1335/// Helper for check-and-exit error handling.
1336///
1337/// For tool use only. NOT FOR USE IN LIBRARY CODE.
1338///
1339class ExitOnError {
1340public:
1341  /// Create an error on exit helper.
1342  ExitOnError(std::string Banner = "", int DefaultErrorExitCode = 1)
1343      : Banner(std::move(Banner)),
1344        GetExitCode([=](const Error &) { return DefaultErrorExitCode; }) {}
1345 
1346  /// Set the banner string for any errors caught by operator().
1347  void setBanner(std::string Banner) { this->Banner = std::move(Banner); }
1348 
1349  /// Set the exit-code mapper function.
1350  void setExitCodeMapper(std::function<int(const Error &)> GetExitCode) {
1351    this->GetExitCode = std::move(GetExitCode);
1352  }
1353 
1354  /// Check Err. If it's in a failure state log the error(s) and exit.
1355  void operator()(Error Err) const { checkError(std::move(Err)); }
1356 
1357  /// Check E. If it's in a success state then return the contained value. If
1358  /// it's in a failure state log the error(s) and exit.
1359  template <typename T> T operator()(Expected<T> &&E) const {
1360    checkError(E.takeError());
1361    return std::move(*E);
1362  }
1363 
1364  /// Check E. If it's in a success state then return the contained reference. If
1365  /// it's in a failure state log the error(s) and exit.
1366  template <typename T> T& operator()(Expected<T&> &&E) const {
1367    checkError(E.takeError());
1368    return *E;
1369  }
1370 
1371private:
1372  void checkError(Error Err) const {
1373    if (Err) {
1374      int ExitCode = GetExitCode(Err);
1375      logAllUnhandledErrors(std::move(Err), errs(), Banner);
1376      exit(ExitCode);
1377    }
1378  }
1379 
1380  std::string Banner;
1381  std::function<int(const Error &)> GetExitCode;
1382};
1383 
1384/// Conversion from Error to LLVMErrorRef for C error bindings.
1385inline LLVMErrorRef wrap(Error Err) {
1386  return reinterpret_cast<LLVMErrorRef>(Err.takePayload().release());
1387}
1388 
1389/// Conversion from LLVMErrorRef to Error for C error bindings.
1390inline Error unwrap(LLVMErrorRef ErrRef) {
1391  return Error(std::unique_ptr<ErrorInfoBase>(
1392      reinterpret_cast<ErrorInfoBase *>(ErrRef)));
1393}
1394 
1395} // end namespace llvm
1396 
1397#endif // LLVM_SUPPORT_ERROR_H