/build/source/clang-tools-extra/clangd/ConfigCompile.cpp

Bug Summary

File:	build/source/clang-tools-extra/clangd/ConfigCompile.cpp
Warning:	line 270, column 27 Potential leak of memory pointed to by field '_M_pi'

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name ConfigCompile.cpp -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 -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -relaxed-aliasing -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/source/build-llvm/tools/clang/stage2-bins -resource-dir /usr/lib/llvm-17/lib/clang/17 -D CLANG_REPOSITORY_STRING="++20230510111145+7df43bdb42ae-1~exp1~20230510111303.1288" -D _DEBUG -D _GLIBCXX_ASSERTIONS -D _GNU_SOURCE -D _LIBCPP_ENABLE_ASSERTIONS -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I tools/clang/tools/extra/clangd -I /build/source/clang-tools-extra/clangd -I /build/source/clang-tools-extra/clangd/../include-cleaner/include -I tools/clang/tools/extra/clangd/../clang-tidy -I /build/source/clang/include -I tools/clang/include -I include -I /build/source/llvm/include -I /build/source/clang-tools-extra/pseudo/lib/../include -D _FORTIFY_SOURCE=2 -D NDEBUG -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-17/lib/clang/17/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fmacro-prefix-map=/build/source/build-llvm/tools/clang/stage2-bins=build-llvm/tools/clang/stage2-bins -fmacro-prefix-map=/build/source/= -fcoverage-prefix-map=/build/source/build-llvm/tools/clang/stage2-bins=build-llvm/tools/clang/stage2-bins -fcoverage-prefix-map=/build/source/= -source-date-epoch 1683717183 -O2 -Wno-unused-command-line-argument -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -Wno-misleading-indentation -std=c++17 -fdeprecated-macro -fdebug-compilation-dir=/build/source/build-llvm/tools/clang/stage2-bins -fdebug-prefix-map=/build/source/build-llvm/tools/clang/stage2-bins=build-llvm/tools/clang/stage2-bins -fdebug-prefix-map=/build/source/= -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -fcolor-diagnostics -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2023-05-10-133810-16478-1 -x c++ /build/source/clang-tools-extra/clangd/ConfigCompile.cpp

/build/source/clang-tools-extra/clangd/ConfigCompile.cpp

→

1//===--- ConfigCompile.cpp - Translating Fragments into Config ------------===//
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// Fragments are applied to Configs in two steps:
10//
11// 1. (When the fragment is first loaded)
12//    FragmentCompiler::compile() traverses the Fragment and creates
13//    function objects that know how to apply the configuration.
14// 2. (Every time a config is required)
15//    CompiledFragment() executes these functions to populate the Config.
16//
17// Work could be split between these steps in different ways. We try to
18// do as much work as possible in the first step. For example, regexes are
19// compiled in stage 1 and captured by the apply function. This is because:
20//
21//  - it's more efficient, as the work done in stage 1 must only be done once
22//  - problems can be reported in stage 1, in stage 2 we must silently recover
23//
24//===----------------------------------------------------------------------===//

26#include "CompileCommands.h"
27#include "Config.h"
28#include "ConfigFragment.h"
29#include "ConfigProvider.h"
30#include "Diagnostics.h"
31#include "Feature.h"
32#include "TidyProvider.h"
33#include "support/Logger.h"
34#include "support/Path.h"
35#include "support/Trace.h"
36#include "llvm/ADT/STLExtras.h"
37#include "llvm/ADT/SmallString.h"
38#include "llvm/ADT/StringRef.h"
39#include "llvm/Support/FileSystem.h"
40#include "llvm/Support/FormatVariadic.h"
41#include "llvm/Support/Path.h"
42#include "llvm/Support/Regex.h"
43#include "llvm/Support/SMLoc.h"
44#include "llvm/Support/SourceMgr.h"
45#include <algorithm>
46#include <memory>
47#include <optional>
48#include <string>
49#include <vector>

51namespace clang {
52namespace clangd {
53namespace config {
54namespace {

56// Returns an empty stringref if Path is not under FragmentDir. Returns Path
57// as-is when FragmentDir is empty.
58llvm::StringRef configRelative(llvm::StringRef Path,
                             llvm::StringRef FragmentDir) {
if (FragmentDir.empty())
  return Path;
if (!Path.consume_front(FragmentDir))
  return llvm::StringRef();
return Path.empty() ? "." : Path;
65}

67struct CompiledFragmentImpl {
// The independent conditions to check before using settings from this config.
// The following fragment has *two* conditions:
//   If: { Platform: [mac, linux], PathMatch: foo/.* }
// All of them must be satisfied: the platform and path conditions are ANDed.
// The OR logic for the platform condition is implemented inside the function.
std::vector<llvm::unique_function<bool(const Params &) const>> Conditions;
// Mutations that this fragment will apply to the configuration.
// These are invoked only if the conditions are satisfied.
std::vector<llvm::unique_function<void(const Params &, Config &) const>>
    Apply;

bool operator()(const Params &P, Config &C) const {
  for (const auto &C : Conditions) {
    if (!C(P)) {
      dlog("Config fragment {0}: condition not met", this)do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
(::clang::clangd::detail::debugType("clang-tools-extra/clangd/ConfigCompile.cpp"
))) { ::clang::clangd::detail::log(Logger::Debug, "Config fragment {0}: condition not met"
, this); } } while (false);
      return false;
    }
  }
  dlog("Config fragment {0}: applying {1} rules", this, Apply.size())do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType
(::clang::clangd::detail::debugType("clang-tools-extra/clangd/ConfigCompile.cpp"
))) { ::clang::clangd::detail::log(Logger::Debug, "Config fragment {0}: applying {1} rules"
, this, Apply.size()); } } while (false);
  for (const auto &A : Apply)
    A(P, C);
  return true;
}
91};

93// Wrapper around condition compile() functions to reduce arg-passing.
94struct FragmentCompiler {
FragmentCompiler(CompiledFragmentImpl &Out, DiagnosticCallback D,
                 llvm::SourceMgr *SM)
    : Out(Out), Diagnostic(D), SourceMgr(SM) {}
CompiledFragmentImpl &Out;
DiagnosticCallback Diagnostic;
llvm::SourceMgr *SourceMgr;
// Normalized Fragment::SourceInfo::Directory.
std::string FragmentDirectory;
bool Trusted = false;

std::optional<llvm::Regex>
compileRegex(const Located<std::string> &Text,
             llvm::Regex::RegexFlags Flags = llvm::Regex::NoFlags) {
  std::string Anchored = "^(" + *Text + ")$";
  llvm::Regex Result(Anchored, Flags);
  std::string RegexError;
  if (!Result.isValid(RegexError)) {
    diag(Error, "Invalid regex " + Anchored + ": " + RegexError, Text.Range);
    return std::nullopt;
  }
  return std::move(Result);
}

std::optional<std::string> makeAbsolute(Located<std::string> Path,
                                        llvm::StringLiteral Description,
                                        llvm::sys::path::Style Style) {
  if (llvm::sys::path::is_absolute(*Path))
    return *Path;
  if (FragmentDirectory.empty()) {
    diag(Error,
         llvm::formatv(
             "{0} must be an absolute path, because this fragment is not "
             "associated with any directory.",
             Description)
             .str(),
         Path.Range);
    return std::nullopt;
  }
  llvm::SmallString<256> AbsPath = llvm::StringRef(*Path);
  llvm::sys::fs::make_absolute(FragmentDirectory, AbsPath);
  llvm::sys::path::native(AbsPath, Style);
  return AbsPath.str().str();
}

// Helper with similar API to StringSwitch, for parsing enum values.
template <typename T> class EnumSwitch {
  FragmentCompiler &Outer;
  llvm::StringRef EnumName;
  const Located<std::string> &Input;
  std::optional<T> Result;
  llvm::SmallVector<llvm::StringLiteral> ValidValues;

public:
  EnumSwitch(llvm::StringRef EnumName, const Located<std::string> &In,
             FragmentCompiler &Outer)
      : Outer(Outer), EnumName(EnumName), Input(In) {}

  EnumSwitch &map(llvm::StringLiteral Name, T Value) {
    assert(!llvm::is_contained(ValidValues, Name) && "Duplicate value!")(static_cast <bool> (!llvm::is_contained(ValidValues, Name
) && "Duplicate value!") ? void (0) : __assert_fail (
"!llvm::is_contained(ValidValues, Name) && \"Duplicate value!\""
, "clang-tools-extra/clangd/ConfigCompile.cpp", 153, __extension__
 __PRETTY_FUNCTION__));
    ValidValues.push_back(Name);
    if (!Result && *Input == Name)
      Result = Value;
    return *this;
  }

  std::optional<T> value() {
    if (!Result)
      Outer.diag(
          Warning,
          llvm::formatv("Invalid {0} value '{1}'. Valid values are {2}.",
                        EnumName, *Input, llvm::join(ValidValues, ", "))
              .str(),
          Input.Range);
    return Result;
  };
};

// Attempt to parse a specified string into an enum.
// Yields std::nullopt and produces a diagnostic on failure.
//
// std::optional<T> Value = compileEnum<En>("Foo", Frag.Foo)
//    .map("Foo", Enum::Foo)
//    .map("Bar", Enum::Bar)
//    .value();
template <typename T>
EnumSwitch<T> compileEnum(llvm::StringRef EnumName,
                          const Located<std::string> &In) {
  return EnumSwitch<T>(EnumName, In, *this);
}

void compile(Fragment &&F) {
  Trusted = F.Source.Trusted;
  if (!F.Source.Directory.empty()) {
7
←
Assuming the condition is false→
8
←
Taking false branch→
    FragmentDirectory = llvm::sys::path::convert_to_slash(F.Source.Directory);
    if (FragmentDirectory.back() != '/')
      FragmentDirectory += '/';
  }
  compile(std::move(F.If));
  compile(std::move(F.CompileFlags));
9
←
Calling 'FragmentCompiler::compile'→
  compile(std::move(F.Index));
  compile(std::move(F.Diagnostics));
  compile(std::move(F.Completion));
  compile(std::move(F.Hover));
  compile(std::move(F.InlayHints));
  compile(std::move(F.Style));
}

void compile(Fragment::IfBlock &&F) {
  if (F.HasUnrecognizedCondition)
    Out.Conditions.push_back([&](const Params &) { return false; });

206#ifdef CLANGD_PATH_CASE_INSENSITIVE
  llvm::Regex::RegexFlags Flags = llvm::Regex::IgnoreCase;
208#else
  llvm::Regex::RegexFlags Flags = llvm::Regex::NoFlags;
210#endif

  auto PathMatch = std::make_unique<std::vector<llvm::Regex>>();
  for (auto &Entry : F.PathMatch) {
    if (auto RE = compileRegex(Entry, Flags))
      PathMatch->push_back(std::move(*RE));
  }
  if (!PathMatch->empty()) {
    Out.Conditions.push_back(
        [PathMatch(std::move(PathMatch)),
         FragmentDir(FragmentDirectory)](const Params &P) {
          if (P.Path.empty())
            return false;
          llvm::StringRef Path = configRelative(P.Path, FragmentDir);
          // Ignore the file if it is not nested under Fragment.
          if (Path.empty())
            return false;
          return llvm::any_of(*PathMatch, [&](const llvm::Regex &RE) {
            return RE.match(Path);
          });
        });
  }

  auto PathExclude = std::make_unique<std::vector<llvm::Regex>>();
  for (auto &Entry : F.PathExclude) {
    if (auto RE = compileRegex(Entry, Flags))
      PathExclude->push_back(std::move(*RE));
  }
  if (!PathExclude->empty()) {
    Out.Conditions.push_back(
        [PathExclude(std::move(PathExclude)),
         FragmentDir(FragmentDirectory)](const Params &P) {
          if (P.Path.empty())
            return false;
          llvm::StringRef Path = configRelative(P.Path, FragmentDir);
          // Ignore the file if it is not nested under Fragment.
          if (Path.empty())
            return true;
          return llvm::none_of(*PathExclude, [&](const llvm::Regex &RE) {
            return RE.match(Path);
          });
        });
  }
}

void compile(Fragment::CompileFlagsBlock &&F) {
  if (F.Compiler)
10
←
Assuming the condition is false→
11
←
Taking false branch→
    Out.Apply.push_back(
        [Compiler(std::move(**F.Compiler))](const Params &, Config &C) {
          C.CompileFlags.Edits.push_back(
              [Compiler](std::vector<std::string> &Args) {
                if (!Args.empty())
                  Args.front() = Compiler;
              });
        });

  if (!F.Remove.empty()) {
12
←
Assuming the condition is true→
13
←
Taking true branch→
    auto Remove = std::make_shared<ArgStripper>();
14
←
Calling 'make_shared<clang::clangd::ArgStripper, >'→
32
←
Returned allocated memory→
    for (auto &A : F.Remove)
      Remove->strip(*A);
    Out.Apply.push_back([Remove(std::shared_ptr<const ArgStripper>(
33
←
Potential leak of memory pointed to by field '_M_pi'
                            std::move(Remove)))](const Params &, Config &C) {
      C.CompileFlags.Edits.push_back(
          [Remove](std::vector<std::string> &Args) {
            Remove->process(Args);
          });
    });
  }

  if (!F.Add.empty()) {
    std::vector<std::string> Add;
    for (auto &A : F.Add)
      Add.push_back(std::move(*A));
    Out.Apply.push_back([Add(std::move(Add))](const Params &, Config &C) {
      C.CompileFlags.Edits.push_back([Add](std::vector<std::string> &Args) {
        // The point to insert at. Just append when `--` isn't present.
        auto It = llvm::find(Args, "--");
        Args.insert(It, Add.begin(), Add.end());
      });
    });
  }

  if (F.CompilationDatabase) {
    std::optional<Config::CDBSearchSpec> Spec;
    if (**F.CompilationDatabase == "Ancestors") {
      Spec.emplace();
      Spec->Policy = Config::CDBSearchSpec::Ancestors;
    } else if (**F.CompilationDatabase == "None") {
      Spec.emplace();
      Spec->Policy = Config::CDBSearchSpec::NoCDBSearch;
    } else {
      if (auto Path =
              makeAbsolute(*F.CompilationDatabase, "CompilationDatabase",
                           llvm::sys::path::Style::native)) {
        // Drop trailing slash to put the path in canonical form.
        // Should makeAbsolute do this?
        llvm::StringRef Rel = llvm::sys::path::relative_path(*Path);
        if (!Rel.empty() && llvm::sys::path::is_separator(Rel.back()))
          Path->pop_back();

        Spec.emplace();
        Spec->Policy = Config::CDBSearchSpec::FixedDir;
        Spec->FixedCDBPath = std::move(Path);
      }
    }
    if (Spec)
      Out.Apply.push_back(
          [Spec(std::move(*Spec))](const Params &, Config &C) {
            C.CompileFlags.CDBSearch = Spec;
          });
  }
}

void compile(Fragment::IndexBlock &&F) {
  if (F.Background) {
    if (auto Val = compileEnum<Config::BackgroundPolicy>("Background",
                                                         **F.Background)
                       .map("Build", Config::BackgroundPolicy::Build)
                       .map("Skip", Config::BackgroundPolicy::Skip)
                       .value())
      Out.Apply.push_back(
          [Val](const Params &, Config &C) { C.Index.Background = *Val; });
  }
  if (F.External)
    compile(std::move(**F.External), F.External->Range);
  if (F.StandardLibrary)
    Out.Apply.push_back(
        [Val(**F.StandardLibrary)](const Params &, Config &C) {
          C.Index.StandardLibrary = Val;
        });
}

void compile(Fragment::IndexBlock::ExternalBlock &&External,
             llvm::SMRange BlockRange) {
  if (External.Server && !Trusted) {
    diag(Error,
         "Remote index may not be specified by untrusted configuration. "
         "Copy this into user config to use it.",
         External.Server->Range);
    return;
  }
351#ifndef CLANGD_ENABLE_REMOTE1
  if (External.Server) {
    elog("Clangd isn't compiled with remote index support, ignoring Server: "
         "{0}",
         *External.Server);
    External.Server.reset();
  }
358#endif
  // Make sure exactly one of the Sources is set.
  unsigned SourceCount = External.File.has_value() +
                         External.Server.has_value() + *External.IsNone;
  if (SourceCount != 1) {
    diag(Error, "Exactly one of File, Server or None must be set.",
         BlockRange);
    return;
  }
  Config::ExternalIndexSpec Spec;
  if (External.Server) {
    Spec.Kind = Config::ExternalIndexSpec::Server;
    Spec.Location = std::move(**External.Server);
  } else if (External.File) {
    Spec.Kind = Config::ExternalIndexSpec::File;
    auto AbsPath = makeAbsolute(std::move(*External.File), "File",
                                llvm::sys::path::Style::native);
    if (!AbsPath)
      return;
    Spec.Location = std::move(*AbsPath);
  } else {
    assert(*External.IsNone)(static_cast <bool> (*External.IsNone) ? void (0) : __assert_fail
 ("*External.IsNone", "clang-tools-extra/clangd/ConfigCompile.cpp"
, 379, __extension__ __PRETTY_FUNCTION__));
    Spec.Kind = Config::ExternalIndexSpec::None;
  }
  if (Spec.Kind != Config::ExternalIndexSpec::None) {
    // Make sure MountPoint is an absolute path with forward slashes.
    if (!External.MountPoint)
      External.MountPoint.emplace(FragmentDirectory);
    if ((**External.MountPoint).empty()) {
      diag(Error, "A mountpoint is required.", BlockRange);
      return;
    }
    auto AbsPath = makeAbsolute(std::move(*External.MountPoint), "MountPoint",
                                llvm::sys::path::Style::posix);
    if (!AbsPath)
      return;
    Spec.MountPoint = std::move(*AbsPath);
  }
  Out.Apply.push_back([Spec(std::move(Spec))](const Params &P, Config &C) {
    if (Spec.Kind == Config::ExternalIndexSpec::None) {
      C.Index.External = Spec;
      return;
    }
    if (P.Path.empty() || !pathStartsWith(Spec.MountPoint, P.Path,
                                          llvm::sys::path::Style::posix))
      return;
    C.Index.External = Spec;
    // Disable background indexing for the files under the mountpoint.
    // Note that this will overwrite statements in any previous fragments
    // (including the current one).
    C.Index.Background = Config::BackgroundPolicy::Skip;
  });
}

void compile(Fragment::DiagnosticsBlock &&F) {
  std::vector<std::string> Normalized;
  for (const auto &Suppressed : F.Suppress) {
    if (*Suppressed == "*") {
      Out.Apply.push_back([&](const Params &, Config &C) {
        C.Diagnostics.SuppressAll = true;
        C.Diagnostics.Suppress.clear();
      });
      return;
    }
    Normalized.push_back(normalizeSuppressedCode(*Suppressed).str());
  }
  if (!Normalized.empty())
    Out.Apply.push_back(
        [Normalized(std::move(Normalized))](const Params &, Config &C) {
          if (C.Diagnostics.SuppressAll)
            return;
          for (llvm::StringRef N : Normalized)
            C.Diagnostics.Suppress.insert(N);
        });

  if (F.UnusedIncludes) {
    auto Val = compileEnum<Config::IncludesPolicy>("UnusedIncludes",
                                                   **F.UnusedIncludes)
                   .map("Strict", Config::IncludesPolicy::Strict)
                   .map("None", Config::IncludesPolicy::None)
                   .value();
    if (!Val && **F.UnusedIncludes == "Experiment") {
      diag(Warning,
           "Experiment is deprecated for UnusedIncludes, use Strict instead.",
           F.UnusedIncludes->Range);
      Val = Config::IncludesPolicy::Strict;
    }
    if (Val) {
      Out.Apply.push_back([Val](const Params &, Config &C) {
        C.Diagnostics.UnusedIncludes = *Val;
      });
    }
  }

  if (F.AllowStalePreamble) {
    if (auto Val = F.AllowStalePreamble)
      Out.Apply.push_back([Val](const Params &, Config &C) {
        C.Diagnostics.AllowStalePreamble = **Val;
      });
  }

  if (F.MissingIncludes)
    if (auto Val = compileEnum<Config::IncludesPolicy>("MissingIncludes",
                                                       **F.MissingIncludes)
                       .map("Strict", Config::IncludesPolicy::Strict)
                       .map("None", Config::IncludesPolicy::None)
                       .value())
      Out.Apply.push_back([Val](const Params &, Config &C) {
        C.Diagnostics.MissingIncludes = *Val;
      });

  compile(std::move(F.Includes));
  compile(std::move(F.ClangTidy));
}

void compile(Fragment::StyleBlock &&F) {
  if (!F.FullyQualifiedNamespaces.empty()) {
    std::vector<std::string> FullyQualifiedNamespaces;
    for (auto &N : F.FullyQualifiedNamespaces) {
      // Normalize the data by dropping both leading and trailing ::
      StringRef Namespace(*N);
      Namespace.consume_front("::");
      Namespace.consume_back("::");
      FullyQualifiedNamespaces.push_back(Namespace.str());
    }
    Out.Apply.push_back([FullyQualifiedNamespaces(
                            std::move(FullyQualifiedNamespaces))](
                            const Params &, Config &C) {
      C.Style.FullyQualifiedNamespaces.insert(
          C.Style.FullyQualifiedNamespaces.begin(),
          FullyQualifiedNamespaces.begin(), FullyQualifiedNamespaces.end());
    });
  }
}

void appendTidyCheckSpec(std::string &CurSpec,
                         const Located<std::string> &Arg, bool IsPositive) {
  StringRef Str = StringRef(*Arg).trim();
  // Don't support negating here, its handled if the item is in the Add or
  // Remove list.
  if (Str.startswith("-") || Str.contains(',')) {
    diag(Error, "Invalid clang-tidy check name", Arg.Range);
    return;
  }
  if (!Str.contains('*') && !isRegisteredTidyCheck(Str)) {
    diag(Warning,
         llvm::formatv("clang-tidy check '{0}' was not found", Str).str(),
         Arg.Range);
    return;
  }
  CurSpec += ',';
  if (!IsPositive)
    CurSpec += '-';
  CurSpec += Str;
}

void compile(Fragment::DiagnosticsBlock::ClangTidyBlock &&F) {
  std::string Checks;
  for (auto &CheckGlob : F.Add)
    appendTidyCheckSpec(Checks, CheckGlob, true);

  for (auto &CheckGlob : F.Remove)
    appendTidyCheckSpec(Checks, CheckGlob, false);

  if (!Checks.empty())
    Out.Apply.push_back(
        [Checks = std::move(Checks)](const Params &, Config &C) {
          C.Diagnostics.ClangTidy.Checks.append(
              Checks,
              C.Diagnostics.ClangTidy.Checks.empty() ? /*skip comma*/ 1 : 0,
              std::string::npos);
        });
  if (!F.CheckOptions.empty()) {
    std::vector<std::pair<std::string, std::string>> CheckOptions;
    for (auto &Opt : F.CheckOptions)
      CheckOptions.emplace_back(std::move(*Opt.first),
                                std::move(*Opt.second));
    Out.Apply.push_back(
        [CheckOptions = std::move(CheckOptions)](const Params &, Config &C) {
          for (auto &StringPair : CheckOptions)
            C.Diagnostics.ClangTidy.CheckOptions.insert_or_assign(
                StringPair.first, StringPair.second);
        });
  }
}

void compile(Fragment::DiagnosticsBlock::IncludesBlock &&F) {
545#ifdef CLANGD_PATH_CASE_INSENSITIVE
  static llvm::Regex::RegexFlags Flags = llvm::Regex::IgnoreCase;
547#else
  static llvm::Regex::RegexFlags Flags = llvm::Regex::NoFlags;
549#endif
  auto Filters = std::make_shared<std::vector<llvm::Regex>>();
  for (auto &HeaderPattern : F.IgnoreHeader) {
    // Anchor on the right.
    std::string AnchoredPattern = "(" + *HeaderPattern + ")$";
    llvm::Regex CompiledRegex(AnchoredPattern, Flags);
    std::string RegexError;
    if (!CompiledRegex.isValid(RegexError)) {
      diag(Warning,
           llvm::formatv("Invalid regular expression '{0}': {1}",
                         *HeaderPattern, RegexError)
               .str(),
           HeaderPattern.Range);
      continue;
    }
    Filters->push_back(std::move(CompiledRegex));
  }
  if (Filters->empty())
    return;
  auto Filter = [Filters](llvm::StringRef Path) {
    for (auto &Regex : *Filters)
      if (Regex.match(Path))
        return true;
    return false;
  };
  Out.Apply.push_back([Filter](const Params &, Config &C) {
    C.Diagnostics.Includes.IgnoreHeader.emplace_back(Filter);
  });
}

void compile(Fragment::CompletionBlock &&F) {
  if (F.AllScopes) {
    Out.Apply.push_back(
        [AllScopes(**F.AllScopes)](const Params &, Config &C) {
          C.Completion.AllScopes = AllScopes;
        });
  }
}

void compile(Fragment::HoverBlock &&F) {
  if (F.ShowAKA) {
    Out.Apply.push_back([ShowAKA(**F.ShowAKA)](const Params &, Config &C) {
      C.Hover.ShowAKA = ShowAKA;
    });
  }
}

void compile(Fragment::InlayHintsBlock &&F) {
  if (F.Enabled)
    Out.Apply.push_back([Value(**F.Enabled)](const Params &, Config &C) {
      C.InlayHints.Enabled = Value;
    });
  if (F.ParameterNames)
    Out.Apply.push_back(
        [Value(**F.ParameterNames)](const Params &, Config &C) {
          C.InlayHints.Parameters = Value;
        });
  if (F.DeducedTypes)
    Out.Apply.push_back([Value(**F.DeducedTypes)](const Params &, Config &C) {
      C.InlayHints.DeducedTypes = Value;
    });
  if (F.Designators)
    Out.Apply.push_back([Value(**F.Designators)](const Params &, Config &C) {
      C.InlayHints.Designators = Value;
    });
  if (F.TypeNameLimit)
    Out.Apply.push_back(
        [Value(**F.TypeNameLimit)](const Params &, Config &C) {
          C.InlayHints.TypeNameLimit = Value;
        });
}

constexpr static llvm::SourceMgr::DiagKind Error = llvm::SourceMgr::DK_Error;
constexpr static llvm::SourceMgr::DiagKind Warning =
    llvm::SourceMgr::DK_Warning;
void diag(llvm::SourceMgr::DiagKind Kind, llvm::StringRef Message,
          llvm::SMRange Range) {
  if (Range.isValid() && SourceMgr != nullptr)
    Diagnostic(SourceMgr->GetMessage(Range.Start, Kind, Message, Range));
  else
    Diagnostic(llvm::SMDiagnostic("", Kind, Message));
}
631};

633} // namespace

635CompiledFragment Fragment::compile(DiagnosticCallback D) && {
llvm::StringRef ConfigFile = "<unknown>";
std::pair<unsigned, unsigned> LineCol = {0, 0};
if (auto *SM = Source.Manager.get()) {
1
Assuming 'SM' is null→
2
←
Taking false branch→
  unsigned BufID = SM->getMainFileID();
  LineCol = SM->getLineAndColumn(Source.Location, BufID);
  ConfigFile = SM->getBufferInfo(BufID).Buffer->getBufferIdentifier();
}
trace::Span Tracer("ConfigCompile");
SPAN_ATTACH(Tracer, "ConfigFile", ConfigFile)do { if (auto *Args = (Tracer).Args) (*Args)["ConfigFile"] = ConfigFile
; } while (0);
3
←
Assuming 'Args' is null→
4
←
Taking false branch→
5
←
Loop condition is false.  Exiting loop→
auto Result = std::make_shared<CompiledFragmentImpl>();
vlog("Config fragment: compiling {0}:{1} -> {2} (trusted={3})", ConfigFile,
     LineCol.first, Result.get(), Source.Trusted);

FragmentCompiler{*Result, D, Source.Manager.get()}.compile(std::move(*this));
6
←
Calling 'FragmentCompiler::compile'→
// Return as cheaply-copyable wrapper.
return [Result(std::move(Result))](const Params &P, Config &C) {
  return (*Result)(P, C);
};
654}

656} // namespace config
657} // namespace clangd
658} // namespace clang

←

/usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/bits/shared_ptr.h

→

1// shared_ptr and weak_ptr implementation -*- C++ -*-

3// Copyright (C) 2007-2020 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library.  This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.

11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14// GNU General Public License for more details.

16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.

20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
23// <http://www.gnu.org/licenses/>.

25// GCC Note: Based on files from version 1.32.0 of the Boost library.

27//  shared_count.hpp
28//  Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.

30//  shared_ptr.hpp
31//  Copyright (C) 1998, 1999 Greg Colvin and Beman Dawes.
32//  Copyright (C) 2001, 2002, 2003 Peter Dimov

34//  weak_ptr.hpp
35//  Copyright (C) 2001, 2002, 2003 Peter Dimov

37//  enable_shared_from_this.hpp
38//  Copyright (C) 2002 Peter Dimov

40// Distributed under the Boost Software License, Version 1.0. (See
41// accompanying file LICENSE_1_0.txt or copy at
42// http://www.boost.org/LICENSE_1_0.txt)

44/** @file
*  This is an internal header file, included by other library headers.
*  Do not attempt to use it directly. @headername{memory}
*/

49#ifndef _SHARED_PTR_H1
50#define _SHARED_PTR_H1 1

52#include <bits/shared_ptr_base.h>

54namespace std _GLIBCXX_VISIBILITY(default)__attribute__ ((__visibility__ ("default")))
55{
56_GLIBCXX_BEGIN_NAMESPACE_VERSION

/**
 * @addtogroup pointer_abstractions
 * @{
 */

// 20.7.2.2.11 shared_ptr I/O

/// Write the stored pointer to an ostream.
/// @relates shared_ptr
template<typename _Ch, typename _Tr, typename _Tp, _Lock_policy _Lp>
  inline std::basic_ostream<_Ch, _Tr>&
  operator<<(std::basic_ostream<_Ch, _Tr>& __os,
      const __shared_ptr<_Tp, _Lp>& __p)
  {
    __os << __p.get();
    return __os;
  }

template<typename _Del, typename _Tp, _Lock_policy _Lp>
  inline _Del*
  get_deleter(const __shared_ptr<_Tp, _Lp>& __p) noexcept
  {
80#if __cpp_rtti199711L
    return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del)));
82#else
    return 0;
84#endif
  }

/// 20.7.2.2.10 shared_ptr get_deleter

/// If `__p` has a deleter of type `_Del`, return a pointer to it.
/// @relates shared_ptr
template<typename _Del, typename _Tp>
  inline _Del*
  get_deleter(const shared_ptr<_Tp>& __p) noexcept
  {
95#if __cpp_rtti199711L
    return static_cast<_Del*>(__p._M_get_deleter(typeid(_Del)));
97#else
    return 0;
99#endif
  }

/**
 *  @brief  A smart pointer with reference-counted copy semantics.
 *
 * A `shared_ptr` object is either empty or _owns_ a pointer passed
 * to the constructor. Copies of a `shared_ptr` share ownership of
 * the same pointer. When the last `shared_ptr` that owns the pointer
 * is destroyed or reset, the owned pointer is freed (either by `delete`
 * or by invoking a custom deleter that was passed to the constructor).
 *
 * A `shared_ptr` also stores another pointer, which is usually
 * (but not always) the same pointer as it owns. The stored pointer
 * can be retrieved by calling the `get()` member function.
 *
 * The equality and relational operators for `shared_ptr` only compare
 * the stored pointer returned by `get()`, not the owned pointer.
 * To test whether two `shared_ptr` objects share ownership of the same
 * pointer see `std::shared_ptr::owner_before` and `std::owner_less`.
*/
template<typename _Tp>
  class shared_ptr : public __shared_ptr<_Tp>
  {
    template<typename... _Args>
using _Constructible = typename enable_if<
 is_constructible<__shared_ptr<_Tp>, _Args...>::value
>::type;

    template<typename _Arg>
using _Assignable = typename enable_if<
 is_assignable<__shared_ptr<_Tp>&, _Arg>::value, shared_ptr&
>::type;

  public:

    /// The type pointed to by the stored pointer, remove_extent_t<_Tp>
    using element_type = typename __shared_ptr<_Tp>::element_type;

138#if __cplusplus201703L >= 201703L
139# define __cpp_lib_shared_ptr_weak_type201606 201606
    /// The corresponding weak_ptr type for this shared_ptr
    using weak_type = weak_ptr<_Tp>;
142#endif
    /**
     *  @brief  Construct an empty %shared_ptr.
     *  @post   use_count()==0 && get()==0
     */
    constexpr shared_ptr() noexcept : __shared_ptr<_Tp>() { }

    shared_ptr(const shared_ptr&) noexcept = default; ///< Copy constructor

    /**
     *  @brief  Construct a %shared_ptr that owns the pointer @a __p.
     *  @param  __p  A pointer that is convertible to element_type*.
     *  @post   use_count() == 1 && get() == __p
     *  @throw  std::bad_alloc, in which case @c delete @a __p is called.
     */
    template<typename _Yp, typename = _Constructible<_Yp*>>
explicit
shared_ptr(_Yp* __p) : __shared_ptr<_Tp>(__p) { }

    /**
     *  @brief  Construct a %shared_ptr that owns the pointer @a __p
     *          and the deleter @a __d.
     *  @param  __p  A pointer.
     *  @param  __d  A deleter.
     *  @post   use_count() == 1 && get() == __p
     *  @throw  std::bad_alloc, in which case @a __d(__p) is called.
     *
     *  Requirements: _Deleter's copy constructor and destructor must
     *  not throw
     *
     *  __shared_ptr will release __p by calling __d(__p)
     */
    template<typename _Yp, typename _Deleter,
      typename = _Constructible<_Yp*, _Deleter>>
shared_ptr(_Yp* __p, _Deleter __d)
      : __shared_ptr<_Tp>(__p, std::move(__d)) { }

    /**
     *  @brief  Construct a %shared_ptr that owns a null pointer
     *          and the deleter @a __d.
     *  @param  __p  A null pointer constant.
     *  @param  __d  A deleter.
     *  @post   use_count() == 1 && get() == __p
     *  @throw  std::bad_alloc, in which case @a __d(__p) is called.
     *
     *  Requirements: _Deleter's copy constructor and destructor must
     *  not throw
     *
     *  The last owner will call __d(__p)
     */
    template<typename _Deleter>
shared_ptr(nullptr_t __p, _Deleter __d)
      : __shared_ptr<_Tp>(__p, std::move(__d)) { }

    /**
     *  @brief  Construct a %shared_ptr that owns the pointer @a __p
     *          and the deleter @a __d.
     *  @param  __p  A pointer.
     *  @param  __d  A deleter.
     *  @param  __a  An allocator.
     *  @post   use_count() == 1 && get() == __p
     *  @throw  std::bad_alloc, in which case @a __d(__p) is called.
     *
     *  Requirements: _Deleter's copy constructor and destructor must
     *  not throw _Alloc's copy constructor and destructor must not
     *  throw.
     *
     *  __shared_ptr will release __p by calling __d(__p)
     */
    template<typename _Yp, typename _Deleter, typename _Alloc,
      typename = _Constructible<_Yp*, _Deleter, _Alloc>>
shared_ptr(_Yp* __p, _Deleter __d, _Alloc __a)
: __shared_ptr<_Tp>(__p, std::move(__d), std::move(__a)) { }

    /**
     *  @brief  Construct a %shared_ptr that owns a null pointer
     *          and the deleter @a __d.
     *  @param  __p  A null pointer constant.
     *  @param  __d  A deleter.
     *  @param  __a  An allocator.
     *  @post   use_count() == 1 && get() == __p
     *  @throw  std::bad_alloc, in which case @a __d(__p) is called.
     *
     *  Requirements: _Deleter's copy constructor and destructor must
     *  not throw _Alloc's copy constructor and destructor must not
     *  throw.
     *
     *  The last owner will call __d(__p)
     */
    template<typename _Deleter, typename _Alloc>
shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a)
: __shared_ptr<_Tp>(__p, std::move(__d), std::move(__a)) { }

    // Aliasing constructor

    /**
     *  @brief  Constructs a `shared_ptr` instance that stores `__p`
     *          and shares ownership with `__r`.
     *  @param  __r  A `shared_ptr`.
     *  @param  __p  A pointer that will remain valid while `*__r` is valid.
     *  @post   `get() == __p && use_count() == __r.use_count()`
     *
     *  This can be used to construct a `shared_ptr` to a sub-object
     *  of an object managed by an existing `shared_ptr`. The complete
     *  object will remain valid while any `shared_ptr` owns it, even
     *  if they don't store a pointer to the complete object.
     *
     * @code
     * shared_ptr<pair<int,int>> pii(new pair<int,int>());
     * shared_ptr<int> pi(pii, &pii->first);
     * assert(pii.use_count() == 2);
     * @endcode
     */
    template<typename _Yp>
shared_ptr(const shared_ptr<_Yp>& __r, element_type* __p) noexcept
: __shared_ptr<_Tp>(__r, __p) { }

259#if __cplusplus201703L > 201703L
    // _GLIBCXX_RESOLVE_LIB_DEFECTS
    // 2996. Missing rvalue overloads for shared_ptr operations
    /**
     *  @brief  Constructs a `shared_ptr` instance that stores `__p`
     *          and shares ownership with `__r`.
     *  @param  __r  A `shared_ptr`.
     *  @param  __p  A pointer that will remain valid while `*__r` is valid.
     *  @post   `get() == __p && !__r.use_count() && !__r.get()`
     *
     *  This can be used to construct a `shared_ptr` to a sub-object
     *  of an object managed by an existing `shared_ptr`. The complete
     *  object will remain valid while any `shared_ptr` owns it, even
     *  if they don't store a pointer to the complete object.
     *
     * @code
     * shared_ptr<pair<int,int>> pii(new pair<int,int>());
     * shared_ptr<int> pi1(pii, &pii->first);
     * assert(pii.use_count() == 2);
     * shared_ptr<int> pi2(std::move(pii), &pii->second);
     * assert(pii.use_count() == 0);
     * @endcode
     */
    template<typename _Yp>
shared_ptr(shared_ptr<_Yp>&& __r, element_type* __p) noexcept
: __shared_ptr<_Tp>(std::move(__r), __p) { }
285#endif
    /**
     *  @brief  If @a __r is empty, constructs an empty %shared_ptr;
     *          otherwise construct a %shared_ptr that shares ownership
     *          with @a __r.
     *  @param  __r  A %shared_ptr.
     *  @post   get() == __r.get() && use_count() == __r.use_count()
     */
    template<typename _Yp,
      typename = _Constructible<const shared_ptr<_Yp>&>>
shared_ptr(const shared_ptr<_Yp>& __r) noexcept
      : __shared_ptr<_Tp>(__r) { }

    /**
     *  @brief  Move-constructs a %shared_ptr instance from @a __r.
     *  @param  __r  A %shared_ptr rvalue.
     *  @post   *this contains the old value of @a __r, @a __r is empty.
     */
    shared_ptr(shared_ptr&& __r) noexcept
    : __shared_ptr<_Tp>(std::move(__r)) { }

    /**
     *  @brief  Move-constructs a %shared_ptr instance from @a __r.
     *  @param  __r  A %shared_ptr rvalue.
     *  @post   *this contains the old value of @a __r, @a __r is empty.
     */
    template<typename _Yp, typename = _Constructible<shared_ptr<_Yp>>>
shared_ptr(shared_ptr<_Yp>&& __r) noexcept
: __shared_ptr<_Tp>(std::move(__r)) { }

    /**
     *  @brief  Constructs a %shared_ptr that shares ownership with @a __r
     *          and stores a copy of the pointer stored in @a __r.
     *  @param  __r  A weak_ptr.
     *  @post   use_count() == __r.use_count()
     *  @throw  bad_weak_ptr when __r.expired(),
     *          in which case the constructor has no effect.
     */
    template<typename _Yp, typename = _Constructible<const weak_ptr<_Yp>&>>
explicit shared_ptr(const weak_ptr<_Yp>& __r)
: __shared_ptr<_Tp>(__r) { }

327#if _GLIBCXX_USE_DEPRECATED1
328#pragma GCC diagnostic push
329#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
    template<typename _Yp, typename = _Constructible<auto_ptr<_Yp>>>
shared_ptr(auto_ptr<_Yp>&& __r);
332#pragma GCC diagnostic pop
333#endif

    // _GLIBCXX_RESOLVE_LIB_DEFECTS
    // 2399. shared_ptr's constructor from unique_ptr should be constrained
    template<typename _Yp, typename _Del,
      typename = _Constructible<unique_ptr<_Yp, _Del>>>
shared_ptr(unique_ptr<_Yp, _Del>&& __r)
: __shared_ptr<_Tp>(std::move(__r)) { }

342#if __cplusplus201703L <= 201402L && _GLIBCXX_USE_DEPRECATED1
    // This non-standard constructor exists to support conversions that
    // were possible in C++11 and C++14 but are ill-formed in C++17.
    // If an exception is thrown this constructor has no effect.
    template<typename _Yp, typename _Del,
_Constructible<unique_ptr<_Yp, _Del>, __sp_array_delete>* = 0>
shared_ptr(unique_ptr<_Yp, _Del>&& __r)
: __shared_ptr<_Tp>(std::move(__r), __sp_array_delete()) { }
350#endif

    /**
     *  @brief  Construct an empty %shared_ptr.
     *  @post   use_count() == 0 && get() == nullptr
     */
    constexpr shared_ptr(nullptr_t) noexcept : shared_ptr() { }

    shared_ptr& operator=(const shared_ptr&) noexcept = default;

    template<typename _Yp>
_Assignable<const shared_ptr<_Yp>&>
operator=(const shared_ptr<_Yp>& __r) noexcept
{
 this->__shared_ptr<_Tp>::operator=(__r);
 return *this;
}

368#if _GLIBCXX_USE_DEPRECATED1
369#pragma GCC diagnostic push
370#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
    template<typename _Yp>
_Assignable<auto_ptr<_Yp>>
operator=(auto_ptr<_Yp>&& __r)
{
 this->__shared_ptr<_Tp>::operator=(std::move(__r));
 return *this;
}
378#pragma GCC diagnostic pop
379#endif

    shared_ptr&
    operator=(shared_ptr&& __r) noexcept
    {
this->__shared_ptr<_Tp>::operator=(std::move(__r));
return *this;
    }

    template<class _Yp>
_Assignable<shared_ptr<_Yp>>
operator=(shared_ptr<_Yp>&& __r) noexcept
{
 this->__shared_ptr<_Tp>::operator=(std::move(__r));
 return *this;
}

    template<typename _Yp, typename _Del>
_Assignable<unique_ptr<_Yp, _Del>>
operator=(unique_ptr<_Yp, _Del>&& __r)
{
 this->__shared_ptr<_Tp>::operator=(std::move(__r));
 return *this;
}

  private:
    // This constructor is non-standard, it is used by allocate_shared.
    template<typename _Alloc, typename... _Args>
shared_ptr(_Sp_alloc_shared_tag<_Alloc> __tag, _Args&&... __args)
: __shared_ptr<_Tp>(__tag, std::forward<_Args>(__args)...)
17
←
Calling constructor for '__shared_ptr<clang::clangd::ArgStripper, __gnu_cxx::_S_atomic>'→
29
←
Returning from constructor for '__shared_ptr<clang::clangd::ArgStripper, __gnu_cxx::_S_atomic>'→
{ }

    template<typename _Yp, typename _Alloc, typename... _Args>
friend shared_ptr<_Yp>
allocate_shared(const _Alloc& __a, _Args&&... __args);

    // This constructor is non-standard, it is used by weak_ptr::lock().
    shared_ptr(const weak_ptr<_Tp>& __r, std::nothrow_t)
    : __shared_ptr<_Tp>(__r, std::nothrow) { }

    friend class weak_ptr<_Tp>;
  };

422#if __cpp_deduction_guides201703L >= 201606
template<typename _Tp>
  shared_ptr(weak_ptr<_Tp>) ->  shared_ptr<_Tp>;
template<typename _Tp, typename _Del>
  shared_ptr(unique_ptr<_Tp, _Del>) ->  shared_ptr<_Tp>;
427#endif

// 20.7.2.2.7 shared_ptr comparisons

/// @relates shared_ptr @{

/// Equality operator for shared_ptr objects, compares the stored pointers
template<typename _Tp, typename _Up>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator==(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
  { return __a.get() == __b.get(); }

/// shared_ptr comparison with nullptr
template<typename _Tp>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator==(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
  { return !__a; }

445#ifdef __cpp_lib_three_way_comparison
template<typename _Tp, typename _Up>
  inline strong_ordering
  operator<=>(const shared_ptr<_Tp>& __a,
const shared_ptr<_Up>& __b) noexcept
  { return compare_three_way()(__a.get(), __b.get()); }

template<typename _Tp>
  inline strong_ordering
  operator<=>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
  {
    using pointer = typename shared_ptr<_Tp>::element_type*;
    return compare_three_way()(__a.get(), static_cast<pointer>(nullptr));
  }
459#else
/// shared_ptr comparison with nullptr
template<typename _Tp>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator==(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
  { return !__a; }

/// Inequality operator for shared_ptr objects, compares the stored pointers
template<typename _Tp, typename _Up>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator!=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
  { return __a.get() != __b.get(); }

/// shared_ptr comparison with nullptr
template<typename _Tp>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator!=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
  { return (bool)__a; }

/// shared_ptr comparison with nullptr
template<typename _Tp>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator!=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
  { return (bool)__a; }

/// Relational operator for shared_ptr objects, compares the stored pointers
template<typename _Tp, typename _Up>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator<(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
  {
    using _Tp_elt = typename shared_ptr<_Tp>::element_type;
    using _Up_elt = typename shared_ptr<_Up>::element_type;
    using _Vp = typename common_type<_Tp_elt*, _Up_elt*>::type;
    return less<_Vp>()(__a.get(), __b.get());
  }

/// shared_ptr comparison with nullptr
template<typename _Tp>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator<(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
  {
    using _Tp_elt = typename shared_ptr<_Tp>::element_type;
    return less<_Tp_elt*>()(__a.get(), nullptr);
  }

/// shared_ptr comparison with nullptr
template<typename _Tp>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator<(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
  {
    using _Tp_elt = typename shared_ptr<_Tp>::element_type;
    return less<_Tp_elt*>()(nullptr, __a.get());
  }

/// Relational operator for shared_ptr objects, compares the stored pointers
template<typename _Tp, typename _Up>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator<=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
  { return !(__b < __a); }

/// shared_ptr comparison with nullptr
template<typename _Tp>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator<=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
  { return !(nullptr < __a); }

/// shared_ptr comparison with nullptr
template<typename _Tp>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator<=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
  { return !(__a < nullptr); }

/// Relational operator for shared_ptr objects, compares the stored pointers
template<typename _Tp, typename _Up>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator>(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
  { return (__b < __a); }

/// shared_ptr comparison with nullptr
template<typename _Tp>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator>(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
  { return nullptr < __a; }

/// shared_ptr comparison with nullptr
template<typename _Tp>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator>(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
  { return __a < nullptr; }

/// Relational operator for shared_ptr objects, compares the stored pointers
template<typename _Tp, typename _Up>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator>=(const shared_ptr<_Tp>& __a, const shared_ptr<_Up>& __b) noexcept
  { return !(__a < __b); }

/// shared_ptr comparison with nullptr
template<typename _Tp>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator>=(const shared_ptr<_Tp>& __a, nullptr_t) noexcept
  { return !(__a < nullptr); }

/// shared_ptr comparison with nullptr
template<typename _Tp>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator>=(nullptr_t, const shared_ptr<_Tp>& __a) noexcept
  { return !(nullptr < __a); }
566#endif

// 20.7.2.2.8 shared_ptr specialized algorithms.

/// Swap overload for shared_ptr
template<typename _Tp>
  inline void
  swap(shared_ptr<_Tp>& __a, shared_ptr<_Tp>& __b) noexcept
  { __a.swap(__b); }

// 20.7.2.2.9 shared_ptr casts.

/// Convert type of `shared_ptr`, via `static_cast`
template<typename _Tp, typename _Up>
  inline shared_ptr<_Tp>
  static_pointer_cast(const shared_ptr<_Up>& __r) noexcept
  {
    using _Sp = shared_ptr<_Tp>;
    return _Sp(__r, static_cast<typename _Sp::element_type*>(__r.get()));
  }

/// Convert type of `shared_ptr`, via `const_cast`
template<typename _Tp, typename _Up>
  inline shared_ptr<_Tp>
  const_pointer_cast(const shared_ptr<_Up>& __r) noexcept
  {
    using _Sp = shared_ptr<_Tp>;
    return _Sp(__r, const_cast<typename _Sp::element_type*>(__r.get()));
  }

/// Convert type of `shared_ptr`, via `dynamic_cast`
template<typename _Tp, typename _Up>
  inline shared_ptr<_Tp>
  dynamic_pointer_cast(const shared_ptr<_Up>& __r) noexcept
  {
    using _Sp = shared_ptr<_Tp>;
    if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get()))
return _Sp(__r, __p);
    return _Sp();
  }

607#if __cplusplus201703L >= 201703L
/// Convert type of `shared_ptr`, via `reinterpret_cast`
template<typename _Tp, typename _Up>
  inline shared_ptr<_Tp>
  reinterpret_pointer_cast(const shared_ptr<_Up>& __r) noexcept
  {
    using _Sp = shared_ptr<_Tp>;
    return _Sp(__r, reinterpret_cast<typename _Sp::element_type*>(__r.get()));
  }

617#if __cplusplus201703L > 201703L
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 2996. Missing rvalue overloads for shared_ptr operations

/// Convert type of `shared_ptr` rvalue, via `static_cast`
template<typename _Tp, typename _Up>
  inline shared_ptr<_Tp>
  static_pointer_cast(shared_ptr<_Up>&& __r) noexcept
  {
    using _Sp = shared_ptr<_Tp>;
    return _Sp(std::move(__r),
 static_cast<typename _Sp::element_type*>(__r.get()));
  }

/// Convert type of `shared_ptr` rvalue, via `const_cast`
template<typename _Tp, typename _Up>
  inline shared_ptr<_Tp>
  const_pointer_cast(shared_ptr<_Up>&& __r) noexcept
  {
    using _Sp = shared_ptr<_Tp>;
    return _Sp(std::move(__r),
 const_cast<typename _Sp::element_type*>(__r.get()));
  }

/// Convert type of `shared_ptr` rvalue, via `dynamic_cast`
template<typename _Tp, typename _Up>
  inline shared_ptr<_Tp>
  dynamic_pointer_cast(shared_ptr<_Up>&& __r) noexcept
  {
    using _Sp = shared_ptr<_Tp>;
    if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get()))
return _Sp(std::move(__r), __p);
    return _Sp();
  }

/// Convert type of `shared_ptr` rvalue, via `reinterpret_cast`
template<typename _Tp, typename _Up>
  inline shared_ptr<_Tp>
  reinterpret_pointer_cast(shared_ptr<_Up>&& __r) noexcept
  {
    using _Sp = shared_ptr<_Tp>;
    return _Sp(std::move(__r),
 reinterpret_cast<typename _Sp::element_type*>(__r.get()));
  }
661#endif // C++20
662#endif // C++17

// @}

/**
 * @brief  A non-owning observer for a pointer owned by a shared_ptr
 *
 * A weak_ptr provides a safe alternative to a raw pointer when you want
 * a non-owning reference to an object that is managed by a shared_ptr.
 *
 * Unlike a raw pointer, a weak_ptr can be converted to a new shared_ptr
 * that shares ownership with every other shared_ptr that already owns
 * the pointer. In other words you can upgrade from a non-owning "weak"
 * reference to an owning shared_ptr, without having access to any of
 * the existing shared_ptr objects.
 *
 * Also unlike a raw pointer, a weak_ptr does not become "dangling" after
 * the object it points to has been destroyed. Instead, a weak_ptr
 * becomes _expired_ and can no longer be converted to a shared_ptr that
 * owns the freed pointer, so you cannot accidentally access the pointed-to
 * object after it has been destroyed.
 */
template<typename _Tp>
  class weak_ptr : public __weak_ptr<_Tp>
  {
    template<typename _Arg>
using _Constructible = typename enable_if<
 is_constructible<__weak_ptr<_Tp>, _Arg>::value
>::type;

    template<typename _Arg>
using _Assignable = typename enable_if<
 is_assignable<__weak_ptr<_Tp>&, _Arg>::value, weak_ptr&
>::type;

  public:
    constexpr weak_ptr() noexcept = default;

    template<typename _Yp,
      typename = _Constructible<const shared_ptr<_Yp>&>>
weak_ptr(const shared_ptr<_Yp>& __r) noexcept
: __weak_ptr<_Tp>(__r) { }

    weak_ptr(const weak_ptr&) noexcept = default;

    template<typename _Yp, typename = _Constructible<const weak_ptr<_Yp>&>>
weak_ptr(const weak_ptr<_Yp>& __r) noexcept
: __weak_ptr<_Tp>(__r) { }

    weak_ptr(weak_ptr&&) noexcept = default;

    template<typename _Yp, typename = _Constructible<weak_ptr<_Yp>>>
weak_ptr(weak_ptr<_Yp>&& __r) noexcept
: __weak_ptr<_Tp>(std::move(__r)) { }

    weak_ptr&
    operator=(const weak_ptr& __r) noexcept = default;

    template<typename _Yp>
_Assignable<const weak_ptr<_Yp>&>
operator=(const weak_ptr<_Yp>& __r) noexcept
{
 this->__weak_ptr<_Tp>::operator=(__r);
 return *this;
}

    template<typename _Yp>
_Assignable<const shared_ptr<_Yp>&>
operator=(const shared_ptr<_Yp>& __r) noexcept
{
 this->__weak_ptr<_Tp>::operator=(__r);
 return *this;
}

    weak_ptr&
    operator=(weak_ptr&& __r) noexcept = default;

    template<typename _Yp>
_Assignable<weak_ptr<_Yp>>
operator=(weak_ptr<_Yp>&& __r) noexcept
{
 this->__weak_ptr<_Tp>::operator=(std::move(__r));
 return *this;
}

    shared_ptr<_Tp>
    lock() const noexcept
    { return shared_ptr<_Tp>(*this, std::nothrow); }
  };

752#if __cpp_deduction_guides201703L >= 201606
template<typename _Tp>
  weak_ptr(shared_ptr<_Tp>) ->  weak_ptr<_Tp>;
755#endif

// 20.7.2.3.6 weak_ptr specialized algorithms.
/// Swap overload for weak_ptr
/// @relates weak_ptr
template<typename _Tp>
  inline void
  swap(weak_ptr<_Tp>& __a, weak_ptr<_Tp>& __b) noexcept
  { __a.swap(__b); }


/// Primary template owner_less
template<typename _Tp = void>
  struct owner_less;

/// Void specialization of owner_less compares either shared_ptr or weak_ptr
template<>
  struct owner_less<void> : _Sp_owner_less<void, void>
  { };

/// Partial specialization of owner_less for shared_ptr.
template<typename _Tp>
  struct owner_less<shared_ptr<_Tp>>
  : public _Sp_owner_less<shared_ptr<_Tp>, weak_ptr<_Tp>>
  { };

/// Partial specialization of owner_less for weak_ptr.
template<typename _Tp>
  struct owner_less<weak_ptr<_Tp>>
  : public _Sp_owner_less<weak_ptr<_Tp>, shared_ptr<_Tp>>
  { };

/**
 *  @brief Base class allowing use of member function shared_from_this.
 */
template<typename _Tp>
  class enable_shared_from_this
  {
  protected:
    constexpr enable_shared_from_this() noexcept { }

    enable_shared_from_this(const enable_shared_from_this&) noexcept { }

    enable_shared_from_this&
    operator=(const enable_shared_from_this&) noexcept
    { return *this; }

    ~enable_shared_from_this() { }

  public:
    shared_ptr<_Tp>
    shared_from_this()
    { return shared_ptr<_Tp>(this->_M_weak_this); }

    shared_ptr<const _Tp>
    shared_from_this() const
    { return shared_ptr<const _Tp>(this->_M_weak_this); }

813#if __cplusplus201703L > 201402L || !defined(__STRICT_ANSI__1) // c++1z or gnu++11
814#define __cpp_lib_enable_shared_from_this201603 201603
    weak_ptr<_Tp>
    weak_from_this() noexcept
    { return this->_M_weak_this; }

    weak_ptr<const _Tp>
    weak_from_this() const noexcept
    { return this->_M_weak_this; }
822#endif

  private:
    template<typename _Tp1>
void
_M_weak_assign(_Tp1* __p, const __shared_count<>& __n) const noexcept
{ _M_weak_this._M_assign(__p, __n); }

    // Found by ADL when this is an associated class.
    friend const enable_shared_from_this*
    __enable_shared_from_this_base(const __shared_count<>&,
		     const enable_shared_from_this* __p)
    { return __p; }

    template<typename, _Lock_policy>
friend class __shared_ptr;

    mutable weak_ptr<_Tp>  _M_weak_this;
  };

/// @relates shared_ptr @{

/**
 *  @brief  Create an object that is owned by a shared_ptr.
 *  @param  __a     An allocator.
 *  @param  __args  Arguments for the @a _Tp object's constructor.
 *  @return A shared_ptr that owns the newly created object.
 *  @throw  An exception thrown from @a _Alloc::allocate or from the
 *          constructor of @a _Tp.
 *
 *  A copy of @a __a will be used to allocate memory for the shared_ptr
 *  and the new object.
 */
template<typename _Tp, typename _Alloc, typename... _Args>
  inline shared_ptr<_Tp>
  allocate_shared(const _Alloc& __a, _Args&&... __args)
  {
    return shared_ptr<_Tp>(_Sp_alloc_shared_tag<_Alloc>{__a},
16
←
Calling constructor for 'shared_ptr<clang::clangd::ArgStripper>'→
30
←
Returning from constructor for 'shared_ptr<clang::clangd::ArgStripper>'→
	     std::forward<_Args>(__args)...);
  }

/**
 *  @brief  Create an object that is owned by a shared_ptr.
 *  @param  __args  Arguments for the @a _Tp object's constructor.
 *  @return A shared_ptr that owns the newly created object.
 *  @throw  std::bad_alloc, or an exception thrown from the
 *          constructor of @a _Tp.
 */
template<typename _Tp, typename... _Args>
  inline shared_ptr<_Tp>
  make_shared(_Args&&... __args)
  {
    typedef typename std::remove_cv<_Tp>::type _Tp_nc;
    return std::allocate_shared<_Tp>(std::allocator<_Tp_nc>(),
15
←
Calling 'allocate_shared<clang::clangd::ArgStripper, std::allocator<clang::clangd::ArgStripper>, >'→
31
←
Returned allocated memory→
		       std::forward<_Args>(__args)...);
  }

/// std::hash specialization for shared_ptr.
template<typename _Tp>
  struct hash<shared_ptr<_Tp>>
  : public __hash_base<size_t, shared_ptr<_Tp>>
  {
    size_t
    operator()(const shared_ptr<_Tp>& __s) const noexcept
    {
return std::hash<typename shared_ptr<_Tp>::element_type*>()(__s.get());
    }
  };

// @} relates shared_ptr
// @} group pointer_abstractions

894#if __cplusplus201703L >= 201703L
namespace __detail::__variant
{
  template<typename> struct _Never_valueless_alt; // see <variant>

  // Provide the strong exception-safety guarantee when emplacing a
  // shared_ptr into a variant.
  template<typename _Tp>
    struct _Never_valueless_alt<std::shared_ptr<_Tp>>
    : std::true_type
    { };

  // Provide the strong exception-safety guarantee when emplacing a
  // weak_ptr into a variant.
  template<typename _Tp>
    struct _Never_valueless_alt<std::weak_ptr<_Tp>>
    : std::true_type
    { };
}  // namespace __detail::__variant
913#endif // C++17

915_GLIBCXX_END_NAMESPACE_VERSION
916} // namespace

918#endif // _SHARED_PTR_H

←

/usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/bits/shared_ptr_base.h

→

1// shared_ptr and weak_ptr implementation details -*- C++ -*-

3// Copyright (C) 2007-2020 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library.  This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.

11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14// GNU General Public License for more details.

16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.

20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
23// <http://www.gnu.org/licenses/>.

25// GCC Note: Based on files from version 1.32.0 of the Boost library.

27//  shared_count.hpp
28//  Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.

30//  shared_ptr.hpp
31//  Copyright (C) 1998, 1999 Greg Colvin and Beman Dawes.
32//  Copyright (C) 2001, 2002, 2003 Peter Dimov

34//  weak_ptr.hpp
35//  Copyright (C) 2001, 2002, 2003 Peter Dimov

37//  enable_shared_from_this.hpp
38//  Copyright (C) 2002 Peter Dimov

40// Distributed under the Boost Software License, Version 1.0. (See
41// accompanying file LICENSE_1_0.txt or copy at
42// http://www.boost.org/LICENSE_1_0.txt)

44/** @file bits/shared_ptr_base.h
*  This is an internal header file, included by other library headers.
*  Do not attempt to use it directly. @headername{memory}
*/

49#ifndef _SHARED_PTR_BASE_H1
50#define _SHARED_PTR_BASE_H1 1

52#include <typeinfo>
53#include <bits/allocated_ptr.h>
54#include <bits/refwrap.h>
55#include <bits/stl_function.h>
56#include <ext/aligned_buffer.h>
57#if __cplusplus201703L > 201703L
58# include <compare>
59#endif

61namespace std _GLIBCXX_VISIBILITY(default)__attribute__ ((__visibility__ ("default")))
62{
63_GLIBCXX_BEGIN_NAMESPACE_VERSION

65#if _GLIBCXX_USE_DEPRECATED1
66#pragma GCC diagnostic push
67#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
template<typename> class auto_ptr;
69#pragma GCC diagnostic pop
70#endif

/**
 *  @brief  Exception possibly thrown by @c shared_ptr.
 *  @ingroup exceptions
 */
class bad_weak_ptr : public std::exception
{
public:
  virtual char const* what() const noexcept;

  virtual ~bad_weak_ptr() noexcept;
};

// Substitute for bad_weak_ptr object in the case of -fno-exceptions.
inline void
__throw_bad_weak_ptr()
{ _GLIBCXX_THROW_OR_ABORT(bad_weak_ptr())(__builtin_abort()); }

using __gnu_cxx::_Lock_policy;
using __gnu_cxx::__default_lock_policy;
using __gnu_cxx::_S_single;
using __gnu_cxx::_S_mutex;
using __gnu_cxx::_S_atomic;

// Empty helper class except when the template argument is _S_mutex.
template<_Lock_policy _Lp>
  class _Mutex_base
  {
  protected:
    // The atomic policy uses fully-fenced builtins, single doesn't care.
    enum { _S_need_barriers = 0 };
  };

template<>
  class _Mutex_base<_S_mutex>
  : public __gnu_cxx::__mutex
  {
  protected:
    // This policy is used when atomic builtins are not available.
    // The replacement atomic operations might not have the necessary
    // memory barriers.
    enum { _S_need_barriers = 1 };
  };

template<_Lock_policy _Lp = __default_lock_policy>
  class _Sp_counted_base
  : public _Mutex_base<_Lp>
  {
  public:
    _Sp_counted_base() noexcept
    : _M_use_count(1), _M_weak_count(1) { }

    virtual
    ~_Sp_counted_base() noexcept
    { }

    // Called when _M_use_count drops to zero, to release the resources
    // managed by *this.
    virtual void
    _M_dispose() noexcept = 0;

    // Called when _M_weak_count drops to zero.
    virtual void
    _M_destroy() noexcept
    { delete this; }

    virtual void*
    _M_get_deleter(const std::type_info&) noexcept = 0;

    void
    _M_add_ref_copy()
    { __gnu_cxx::__atomic_add_dispatch(&_M_use_count, 1); }

    void
    _M_add_ref_lock();

    bool
    _M_add_ref_lock_nothrow();

    void
    _M_release() noexcept
    {
      // Be race-detector-friendly.  For more info see bits/c++config.
      _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_use_count);
if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, -1) == 1)
 {
          _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_use_count);
   _M_dispose();
   // There must be a memory barrier between dispose() and destroy()
   // to ensure that the effects of dispose() are observed in the
   // thread that runs destroy().
   // See http://gcc.gnu.org/ml/libstdc++/2005-11/msg00136.html
   if (_Mutex_base<_Lp>::_S_need_barriers)
     {
__atomic_thread_fence (__ATOMIC_ACQ_REL4);
     }

          // Be race-detector-friendly.  For more info see bits/c++config.
          _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count);
   if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count,
				       -1) == 1)
            {
              _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count);
       _M_destroy();
            }
 }
    }

    void
    _M_weak_add_ref() noexcept
    { __gnu_cxx::__atomic_add_dispatch(&_M_weak_count, 1); }

    void
    _M_weak_release() noexcept
    {
      // Be race-detector-friendly. For more info see bits/c++config.
      _GLIBCXX_SYNCHRONIZATION_HAPPENS_BEFORE(&_M_weak_count);
if (__gnu_cxx::__exchange_and_add_dispatch(&_M_weak_count, -1) == 1)
 {
          _GLIBCXX_SYNCHRONIZATION_HAPPENS_AFTER(&_M_weak_count);
   if (_Mutex_base<_Lp>::_S_need_barriers)
     {
       // See _M_release(),
       // destroy() must observe results of dispose()
__atomic_thread_fence (__ATOMIC_ACQ_REL4);
     }
   _M_destroy();
 }
    }

    long
    _M_get_use_count() const noexcept
    {
      // No memory barrier is used here so there is no synchronization
      // with other threads.
      return __atomic_load_n(&_M_use_count, __ATOMIC_RELAXED0);
    }

  private:
    _Sp_counted_base(_Sp_counted_base const&) = delete;
    _Sp_counted_base& operator=(_Sp_counted_base const&) = delete;

    _Atomic_word  _M_use_count;     // #shared
    _Atomic_word  _M_weak_count;    // #weak + (#shared != 0)
  };

template<>
  inline void
  _Sp_counted_base<_S_single>::
  _M_add_ref_lock()
  {
    if (_M_use_count == 0)
__throw_bad_weak_ptr();
    ++_M_use_count;
  }

template<>
  inline void
  _Sp_counted_base<_S_mutex>::
  _M_add_ref_lock()
  {
    __gnu_cxx::__scoped_lock sentry(*this);
    if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0)
{
 _M_use_count = 0;
 __throw_bad_weak_ptr();
}
  }

template<>
  inline void
  _Sp_counted_base<_S_atomic>::
  _M_add_ref_lock()
  {
    // Perform lock-free add-if-not-zero operation.
    _Atomic_word __count = _M_get_use_count();
    do
{
 if (__count == 0)
   __throw_bad_weak_ptr();
 // Replace the current counter value with the old value + 1, as
 // long as it's not changed meanwhile.
}
    while (!__atomic_compare_exchange_n(&_M_use_count, &__count, __count + 1,
			  true, __ATOMIC_ACQ_REL4,
			  __ATOMIC_RELAXED0));
  }

template<>
  inline bool
  _Sp_counted_base<_S_single>::
  _M_add_ref_lock_nothrow()
  {
    if (_M_use_count == 0)
return false;
    ++_M_use_count;
    return true;
  }

template<>
  inline bool
  _Sp_counted_base<_S_mutex>::
  _M_add_ref_lock_nothrow()
  {
    __gnu_cxx::__scoped_lock sentry(*this);
    if (__gnu_cxx::__exchange_and_add_dispatch(&_M_use_count, 1) == 0)
{
 _M_use_count = 0;
 return false;
}
    return true;
  }

template<>
  inline bool
  _Sp_counted_base<_S_atomic>::
  _M_add_ref_lock_nothrow()
  {
    // Perform lock-free add-if-not-zero operation.
    _Atomic_word __count = _M_get_use_count();
    do
{
 if (__count == 0)
   return false;
 // Replace the current counter value with the old value + 1, as
 // long as it's not changed meanwhile.
}
    while (!__atomic_compare_exchange_n(&_M_use_count, &__count, __count + 1,
			  true, __ATOMIC_ACQ_REL4,
			  __ATOMIC_RELAXED0));
    return true;
  }

template<>
  inline void
  _Sp_counted_base<_S_single>::_M_add_ref_copy()
  { ++_M_use_count; }

template<>
  inline void
  _Sp_counted_base<_S_single>::_M_release() noexcept
  {
    if (--_M_use_count == 0)
      {
        _M_dispose();
        if (--_M_weak_count == 0)
          _M_destroy();
      }
  }

template<>
  inline void
  _Sp_counted_base<_S_single>::_M_weak_add_ref() noexcept
  { ++_M_weak_count; }

template<>
  inline void
  _Sp_counted_base<_S_single>::_M_weak_release() noexcept
  {
    if (--_M_weak_count == 0)
      _M_destroy();
  }

template<>
  inline long
  _Sp_counted_base<_S_single>::_M_get_use_count() const noexcept
  { return _M_use_count; }


// Forward declarations.
template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
  class __shared_ptr;

template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
  class __weak_ptr;

template<typename _Tp, _Lock_policy _Lp = __default_lock_policy>
  class __enable_shared_from_this;

template<typename _Tp>
  class shared_ptr;

template<typename _Tp>
  class weak_ptr;

template<typename _Tp>
  struct owner_less;

template<typename _Tp>
  class enable_shared_from_this;

template<_Lock_policy _Lp = __default_lock_policy>
  class __weak_count;

template<_Lock_policy _Lp = __default_lock_policy>
  class __shared_count;


// Counted ptr with no deleter or allocator support
template<typename _Ptr, _Lock_policy _Lp>
  class _Sp_counted_ptr final : public _Sp_counted_base<_Lp>
  {
  public:
    explicit
    _Sp_counted_ptr(_Ptr __p) noexcept
    : _M_ptr(__p) { }

    virtual void
    _M_dispose() noexcept
    { delete _M_ptr; }

    virtual void
    _M_destroy() noexcept
    { delete this; }

    virtual void*
    _M_get_deleter(const std::type_info&) noexcept
    { return nullptr; }

    _Sp_counted_ptr(const _Sp_counted_ptr&) = delete;
    _Sp_counted_ptr& operator=(const _Sp_counted_ptr&) = delete;

  private:
    _Ptr             _M_ptr;
  };

template<>
  inline void
  _Sp_counted_ptr<nullptr_t, _S_single>::_M_dispose() noexcept { }

template<>
  inline void
  _Sp_counted_ptr<nullptr_t, _S_mutex>::_M_dispose() noexcept { }

template<>
  inline void
  _Sp_counted_ptr<nullptr_t, _S_atomic>::_M_dispose() noexcept { }

template<int _Nm, typename _Tp,
  bool __use_ebo = !__is_final(_Tp) && __is_empty(_Tp)>
  struct _Sp_ebo_helper;

/// Specialization using EBO.
template<int _Nm, typename _Tp>
  struct _Sp_ebo_helper<_Nm, _Tp, true> : private _Tp
  {
    explicit _Sp_ebo_helper(const _Tp& __tp) : _Tp(__tp) { }
    explicit _Sp_ebo_helper(_Tp&& __tp) : _Tp(std::move(__tp)) { }

    static _Tp&
    _S_get(_Sp_ebo_helper& __eboh) { return static_cast<_Tp&>(__eboh); }
  };

/// Specialization not using EBO.
template<int _Nm, typename _Tp>
  struct _Sp_ebo_helper<_Nm, _Tp, false>
  {
    explicit _Sp_ebo_helper(const _Tp& __tp) : _M_tp(__tp) { }
    explicit _Sp_ebo_helper(_Tp&& __tp) : _M_tp(std::move(__tp)) { }

    static _Tp&
    _S_get(_Sp_ebo_helper& __eboh)
    { return __eboh._M_tp; }

  private:
    _Tp _M_tp;
  };

// Support for custom deleter and/or allocator
template<typename _Ptr, typename _Deleter, typename _Alloc, _Lock_policy _Lp>
  class _Sp_counted_deleter final : public _Sp_counted_base<_Lp>
  {
    class _Impl : _Sp_ebo_helper<0, _Deleter>, _Sp_ebo_helper<1, _Alloc>
    {
typedef _Sp_ebo_helper<0, _Deleter>	_Del_base;
typedef _Sp_ebo_helper<1, _Alloc>	_Alloc_base;

    public:
_Impl(_Ptr __p, _Deleter __d, const _Alloc& __a) noexcept
: _M_ptr(__p), _Del_base(std::move(__d)), _Alloc_base(__a)
{ }

_Deleter& _M_del() noexcept { return _Del_base::_S_get(*this); }
_Alloc& _M_alloc() noexcept { return _Alloc_base::_S_get(*this); }

_Ptr _M_ptr;
    };

  public:
    using __allocator_type = __alloc_rebind<_Alloc, _Sp_counted_deleter>;

    // __d(__p) must not throw.
    _Sp_counted_deleter(_Ptr __p, _Deleter __d) noexcept
    : _M_impl(__p, std::move(__d), _Alloc()) { }

    // __d(__p) must not throw.
    _Sp_counted_deleter(_Ptr __p, _Deleter __d, const _Alloc& __a) noexcept
    : _M_impl(__p, std::move(__d), __a) { }

    ~_Sp_counted_deleter() noexcept { }

    virtual void
    _M_dispose() noexcept
    { _M_impl._M_del()(_M_impl._M_ptr); }

    virtual void
    _M_destroy() noexcept
    {
__allocator_type __a(_M_impl._M_alloc());
__allocated_ptr<__allocator_type> __guard_ptr{ __a, this };
this->~_Sp_counted_deleter();
    }

    virtual void*
    _M_get_deleter(const std::type_info& __ti) noexcept
    {
487#if __cpp_rtti199711L
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 2400. shared_ptr's get_deleter() should use addressof()
      return __ti == typeid(_Deleter)
 ? std::__addressof(_M_impl._M_del())
 : nullptr;
493#else
      return nullptr;
495#endif
    }

  private:
    _Impl _M_impl;
  };

// helpers for make_shared / allocate_shared

struct _Sp_make_shared_tag
{
private:
  template<typename _Tp, typename _Alloc, _Lock_policy _Lp>
    friend class _Sp_counted_ptr_inplace;

  static const type_info&
  _S_ti() noexcept _GLIBCXX_VISIBILITY(default)__attribute__ ((__visibility__ ("default")))
  {
    alignas(type_info) static constexpr char __tag[sizeof(type_info)] = { };
    return reinterpret_cast<const type_info&>(__tag);
  }

  static bool _S_eq(const type_info&) noexcept;
};

template<typename _Alloc>
  struct _Sp_alloc_shared_tag
  {
    const _Alloc& _M_a;
  };

template<typename _Tp, typename _Alloc, _Lock_policy _Lp>
  class _Sp_counted_ptr_inplace final : public _Sp_counted_base<_Lp>
  {
    class _Impl : _Sp_ebo_helper<0, _Alloc>
    {
typedef _Sp_ebo_helper<0, _Alloc>	_A_base;

    public:
explicit _Impl(_Alloc __a) noexcept : _A_base(__a) { }

_Alloc& _M_alloc() noexcept { return _A_base::_S_get(*this); }

__gnu_cxx::__aligned_buffer<_Tp> _M_storage;
    };

  public:
    using __allocator_type = __alloc_rebind<_Alloc, _Sp_counted_ptr_inplace>;

    // Alloc parameter is not a reference so doesn't alias anything in __args
    template<typename... _Args>
_Sp_counted_ptr_inplace(_Alloc __a, _Args&&... __args)
: _M_impl(__a)
{
 // _GLIBCXX_RESOLVE_LIB_DEFECTS
 // 2070.  allocate_shared should use allocator_traits<A>::construct
 allocator_traits<_Alloc>::construct(__a, _M_ptr(),
     std::forward<_Args>(__args)...); // might throw
}

    ~_Sp_counted_ptr_inplace() noexcept { }

    virtual void
    _M_dispose() noexcept
    {
allocator_traits<_Alloc>::destroy(_M_impl._M_alloc(), _M_ptr());
    }

    // Override because the allocator needs to know the dynamic type
    virtual void
    _M_destroy() noexcept
    {
__allocator_type __a(_M_impl._M_alloc());
__allocated_ptr<__allocator_type> __guard_ptr{ __a, this };
this->~_Sp_counted_ptr_inplace();
    }

  private:
    friend class __shared_count<_Lp>; // To be able to call _M_ptr().

    // No longer used, but code compiled against old libstdc++ headers
    // might still call it from __shared_ptr ctor to get the pointer out.
    virtual void*
    _M_get_deleter(const std::type_info& __ti) noexcept override
    {
auto __ptr = const_cast<typename remove_cv<_Tp>::type*>(_M_ptr());
// Check for the fake type_info first, so we don't try to access it
// as a real type_info object. Otherwise, check if it's the real
// type_info for this class. With RTTI enabled we can check directly,
// or call a library function to do it.
if (&__ti == &_Sp_make_shared_tag::_S_ti()
   ||
587#if __cpp_rtti199711L
   __ti == typeid(_Sp_make_shared_tag)
589#else
   _Sp_make_shared_tag::_S_eq(__ti)
591#endif
  )
 return __ptr;
return nullptr;
    }

    _Tp* _M_ptr() noexcept { return _M_impl._M_storage._M_ptr(); }

    _Impl _M_impl;
  };

// The default deleter for shared_ptr<T[]> and shared_ptr<T[N]>.
struct __sp_array_delete
{
  template<typename _Yp>
    void operator()(_Yp* __p) const { delete[] __p; }
};

template<_Lock_policy _Lp>
  class __shared_count
  {
    template<typename _Tp>
struct __not_alloc_shared_tag { using type = void; };

    template<typename _Tp>
struct __not_alloc_shared_tag<_Sp_alloc_shared_tag<_Tp>> { };

  public:
    constexpr __shared_count() noexcept : _M_pi(0)
    { }

    template<typename _Ptr>
      explicit
__shared_count(_Ptr __p) : _M_pi(0)
{
 __tryif (true)
   {
     _M_pi = new _Sp_counted_ptr<_Ptr, _Lp>(__p);
   }
 __catch(...)if (false)
   {
     delete __p;
     __throw_exception_again;
   }
}

    template<typename _Ptr>
__shared_count(_Ptr __p, /* is_array = */ false_type)
: __shared_count(__p)
{ }

    template<typename _Ptr>
__shared_count(_Ptr __p, /* is_array = */ true_type)
: __shared_count(__p, __sp_array_delete{}, allocator<void>())
{ }

    template<typename _Ptr, typename _Deleter,
      typename = typename __not_alloc_shared_tag<_Deleter>::type>
__shared_count(_Ptr __p, _Deleter __d)
: __shared_count(__p, std::move(__d), allocator<void>())
{ }

    template<typename _Ptr, typename _Deleter, typename _Alloc,
      typename = typename __not_alloc_shared_tag<_Deleter>::type>
__shared_count(_Ptr __p, _Deleter __d, _Alloc __a) : _M_pi(0)
{
 typedef _Sp_counted_deleter<_Ptr, _Deleter, _Alloc, _Lp> _Sp_cd_type;
 __tryif (true)
   {
     typename _Sp_cd_type::__allocator_type __a2(__a);
     auto __guard = std::__allocate_guarded(__a2);
     _Sp_cd_type* __mem = __guard.get();
     ::new (__mem) _Sp_cd_type(__p, std::move(__d), std::move(__a));
     _M_pi = __mem;
     __guard = nullptr;
   }
 __catch(...)if (false)
   {
     __d(__p); // Call _Deleter on __p.
     __throw_exception_again;
   }
}

    template<typename _Tp, typename _Alloc, typename... _Args>
__shared_count(_Tp*& __p, _Sp_alloc_shared_tag<_Alloc> __a,
       _Args&&... __args)
{
 typedef _Sp_counted_ptr_inplace<_Tp, _Alloc, _Lp> _Sp_cp_type;
 typename _Sp_cp_type::__allocator_type __a2(__a._M_a);
 auto __guard = std::__allocate_guarded(__a2);
19
←
Calling '__allocate_guarded<std::allocator<std::_Sp_counted_ptr_inplace<clang::clangd::ArgStripper, std::allocator<clang::clangd::ArgStripper>, __gnu_cxx::_S_atomic>>>'→
27
←
Returned allocated memory→
 _Sp_cp_type* __mem = __guard.get();
 auto __pi = ::new (__mem)
   _Sp_cp_type(__a._M_a, std::forward<_Args>(__args)...);
 __guard = nullptr;
 _M_pi = __pi;
 __p = __pi->_M_ptr();
}

689#if _GLIBCXX_USE_DEPRECATED1
690#pragma GCC diagnostic push
691#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
    // Special case for auto_ptr<_Tp> to provide the strong guarantee.
    template<typename _Tp>
      explicit
__shared_count(std::auto_ptr<_Tp>&& __r);
696#pragma GCC diagnostic pop
697#endif

    // Special case for unique_ptr<_Tp,_Del> to provide the strong guarantee.
    template<typename _Tp, typename _Del>
      explicit
__shared_count(std::unique_ptr<_Tp, _Del>&& __r) : _M_pi(0)
{
 // _GLIBCXX_RESOLVE_LIB_DEFECTS
 // 2415. Inconsistency between unique_ptr and shared_ptr
 if (__r.get() == nullptr)
   return;

 using _Ptr = typename unique_ptr<_Tp, _Del>::pointer;
 using _Del2 = typename conditional<is_reference<_Del>::value,
     reference_wrapper<typename remove_reference<_Del>::type>,
     _Del>::type;
 using _Sp_cd_type
   = _Sp_counted_deleter<_Ptr, _Del2, allocator<void>, _Lp>;
 using _Alloc = allocator<_Sp_cd_type>;
 using _Alloc_traits = allocator_traits<_Alloc>;
 _Alloc __a;
 _Sp_cd_type* __mem = _Alloc_traits::allocate(__a, 1);
 _Alloc_traits::construct(__a, __mem, __r.release(),
		   __r.get_deleter());  // non-throwing
 _M_pi = __mem;
}

    // Throw bad_weak_ptr when __r._M_get_use_count() == 0.
    explicit __shared_count(const __weak_count<_Lp>& __r);

    // Does not throw if __r._M_get_use_count() == 0, caller must check.
    explicit __shared_count(const __weak_count<_Lp>& __r, std::nothrow_t);

    ~__shared_count() noexcept
    {
if (_M_pi != nullptr)
 _M_pi->_M_release();
    }

    __shared_count(const __shared_count& __r) noexcept
    : _M_pi(__r._M_pi)
    {
if (_M_pi != 0)
 _M_pi->_M_add_ref_copy();
    }

    __shared_count&
    operator=(const __shared_count& __r) noexcept
    {
_Sp_counted_base<_Lp>* __tmp = __r._M_pi;
if (__tmp != _M_pi)
 {
   if (__tmp != 0)
     __tmp->_M_add_ref_copy();
   if (_M_pi != 0)
     _M_pi->_M_release();
   _M_pi = __tmp;
 }
return *this;
    }

    void
    _M_swap(__shared_count& __r) noexcept
    {
_Sp_counted_base<_Lp>* __tmp = __r._M_pi;
__r._M_pi = _M_pi;
_M_pi = __tmp;
    }

    long
    _M_get_use_count() const noexcept
    { return _M_pi != 0 ? _M_pi->_M_get_use_count() : 0; }

    bool
    _M_unique() const noexcept
    { return this->_M_get_use_count() == 1; }

    void*
    _M_get_deleter(const std::type_info& __ti) const noexcept
    { return _M_pi ? _M_pi->_M_get_deleter(__ti) : nullptr; }

    bool
    _M_less(const __shared_count& __rhs) const noexcept
    { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }

    bool
    _M_less(const __weak_count<_Lp>& __rhs) const noexcept
    { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }

    // Friend function injected into enclosing namespace and found by ADL
    friend inline bool
    operator==(const __shared_count& __a, const __shared_count& __b) noexcept
    { return __a._M_pi == __b._M_pi; }

  private:
    friend class __weak_count<_Lp>;

    _Sp_counted_base<_Lp>*  _M_pi;
  };


template<_Lock_policy _Lp>
  class __weak_count
  {
  public:
    constexpr __weak_count() noexcept : _M_pi(nullptr)
    { }

    __weak_count(const __shared_count<_Lp>& __r) noexcept
    : _M_pi(__r._M_pi)
    {
if (_M_pi != nullptr)
 _M_pi->_M_weak_add_ref();
    }

    __weak_count(const __weak_count& __r) noexcept
    : _M_pi(__r._M_pi)
    {
if (_M_pi != nullptr)
 _M_pi->_M_weak_add_ref();
    }

    __weak_count(__weak_count&& __r) noexcept
    : _M_pi(__r._M_pi)
    { __r._M_pi = nullptr; }

    ~__weak_count() noexcept
    {
if (_M_pi != nullptr)
 _M_pi->_M_weak_release();
    }

    __weak_count&
    operator=(const __shared_count<_Lp>& __r) noexcept
    {
_Sp_counted_base<_Lp>* __tmp = __r._M_pi;
if (__tmp != nullptr)
 __tmp->_M_weak_add_ref();
if (_M_pi != nullptr)
 _M_pi->_M_weak_release();
_M_pi = __tmp;
return *this;
    }

    __weak_count&
    operator=(const __weak_count& __r) noexcept
    {
_Sp_counted_base<_Lp>* __tmp = __r._M_pi;
if (__tmp != nullptr)
 __tmp->_M_weak_add_ref();
if (_M_pi != nullptr)
 _M_pi->_M_weak_release();
_M_pi = __tmp;
return *this;
    }

    __weak_count&
    operator=(__weak_count&& __r) noexcept
    {
if (_M_pi != nullptr)
 _M_pi->_M_weak_release();
_M_pi = __r._M_pi;
      __r._M_pi = nullptr;
return *this;
    }

    void
    _M_swap(__weak_count& __r) noexcept
    {
_Sp_counted_base<_Lp>* __tmp = __r._M_pi;
__r._M_pi = _M_pi;
_M_pi = __tmp;
    }

    long
    _M_get_use_count() const noexcept
    { return _M_pi != nullptr ? _M_pi->_M_get_use_count() : 0; }

    bool
    _M_less(const __weak_count& __rhs) const noexcept
    { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }

    bool
    _M_less(const __shared_count<_Lp>& __rhs) const noexcept
    { return std::less<_Sp_counted_base<_Lp>*>()(this->_M_pi, __rhs._M_pi); }

    // Friend function injected into enclosing namespace and found by ADL
    friend inline bool
    operator==(const __weak_count& __a, const __weak_count& __b) noexcept
    { return __a._M_pi == __b._M_pi; }

  private:
    friend class __shared_count<_Lp>;

    _Sp_counted_base<_Lp>*  _M_pi;
  };

// Now that __weak_count is defined we can define this constructor:
template<_Lock_policy _Lp>
  inline
  __shared_count<_Lp>::__shared_count(const __weak_count<_Lp>& __r)
  : _M_pi(__r._M_pi)
  {
    if (_M_pi != nullptr)
_M_pi->_M_add_ref_lock();
    else
__throw_bad_weak_ptr();
  }

// Now that __weak_count is defined we can define this constructor:
template<_Lock_policy _Lp>
  inline
  __shared_count<_Lp>::
  __shared_count(const __weak_count<_Lp>& __r, std::nothrow_t)
  : _M_pi(__r._M_pi)
  {
    if (_M_pi != nullptr)
if (!_M_pi->_M_add_ref_lock_nothrow())
 _M_pi = nullptr;
  }

918#define __cpp_lib_shared_ptr_arrays201611L 201611L

// Helper traits for shared_ptr of array:

// A pointer type Y* is said to be compatible with a pointer type T* when
// either Y* is convertible to T* or Y is U[N] and T is U cv [].
template<typename _Yp_ptr, typename _Tp_ptr>
  struct __sp_compatible_with
  : false_type
  { };

template<typename _Yp, typename _Tp>
  struct __sp_compatible_with<_Yp*, _Tp*>
  : is_convertible<_Yp*, _Tp*>::type
  { };

template<typename _Up, size_t _Nm>
  struct __sp_compatible_with<_Up(*)[_Nm], _Up(*)[]>
  : true_type
  { };

template<typename _Up, size_t _Nm>
  struct __sp_compatible_with<_Up(*)[_Nm], const _Up(*)[]>
  : true_type
  { };

template<typename _Up, size_t _Nm>
  struct __sp_compatible_with<_Up(*)[_Nm], volatile _Up(*)[]>
  : true_type
  { };

template<typename _Up, size_t _Nm>
  struct __sp_compatible_with<_Up(*)[_Nm], const volatile _Up(*)[]>
  : true_type
  { };

// Test conversion from Y(*)[N] to U(*)[N] without forming invalid type Y[N].
template<typename _Up, size_t _Nm, typename _Yp, typename = void>
  struct __sp_is_constructible_arrN
  : false_type
  { };

template<typename _Up, size_t _Nm, typename _Yp>
  struct __sp_is_constructible_arrN<_Up, _Nm, _Yp, __void_t<_Yp[_Nm]>>
  : is_convertible<_Yp(*)[_Nm], _Up(*)[_Nm]>::type
  { };

// Test conversion from Y(*)[] to U(*)[] without forming invalid type Y[].
template<typename _Up, typename _Yp, typename = void>
  struct __sp_is_constructible_arr
  : false_type
  { };

template<typename _Up, typename _Yp>
  struct __sp_is_constructible_arr<_Up, _Yp, __void_t<_Yp[]>>
  : is_convertible<_Yp(*)[], _Up(*)[]>::type
  { };

// Trait to check if shared_ptr<T> can be constructed from Y*.
template<typename _Tp, typename _Yp>
  struct __sp_is_constructible;

// When T is U[N], Y(*)[N] shall be convertible to T*;
template<typename _Up, size_t _Nm, typename _Yp>
  struct __sp_is_constructible<_Up[_Nm], _Yp>
  : __sp_is_constructible_arrN<_Up, _Nm, _Yp>::type
  { };

// when T is U[], Y(*)[] shall be convertible to T*;
template<typename _Up, typename _Yp>
  struct __sp_is_constructible<_Up[], _Yp>
  : __sp_is_constructible_arr<_Up, _Yp>::type
  { };

// otherwise, Y* shall be convertible to T*.
template<typename _Tp, typename _Yp>
  struct __sp_is_constructible
  : is_convertible<_Yp*, _Tp*>::type
  { };


// Define operator* and operator-> for shared_ptr<T>.
template<typename _Tp, _Lock_policy _Lp,
  bool = is_array<_Tp>::value, bool = is_void<_Tp>::value>
  class __shared_ptr_access
  {
  public:
    using element_type = _Tp;

    element_type&
    operator*() const noexcept
    {
__glibcxx_assert(_M_get() != nullptr)do { if (! (_M_get() != nullptr)) std::__replacement_assert("/usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/bits/shared_ptr_base.h"
, 1010, __PRETTY_FUNCTION__, "_M_get() != nullptr"); } while (
false);
return *_M_get();
    }

    element_type*
    operator->() const noexcept
    {
_GLIBCXX_DEBUG_PEDASSERT(_M_get() != nullptr);
return _M_get();
    }

  private:
    element_type*
    _M_get() const noexcept
    { return static_cast<const __shared_ptr<_Tp, _Lp>*>(this)->get(); }
  };

// Define operator-> for shared_ptr<cv void>.
template<typename _Tp, _Lock_policy _Lp>
  class __shared_ptr_access<_Tp, _Lp, false, true>
  {
  public:
    using element_type = _Tp;

    element_type*
    operator->() const noexcept
    {
auto __ptr = static_cast<const __shared_ptr<_Tp, _Lp>*>(this)->get();
_GLIBCXX_DEBUG_PEDASSERT(__ptr != nullptr);
return __ptr;
    }
  };

// Define operator[] for shared_ptr<T[]> and shared_ptr<T[N]>.
template<typename _Tp, _Lock_policy _Lp>
  class __shared_ptr_access<_Tp, _Lp, true, false>
  {
  public:
    using element_type = typename remove_extent<_Tp>::type;

1050#if __cplusplus201703L <= 201402L
    [[__deprecated__("shared_ptr<T[]>::operator* is absent from C++17")]]
    element_type&
    operator*() const noexcept
    {
__glibcxx_assert(_M_get() != nullptr)do { if (! (_M_get() != nullptr)) std::__replacement_assert("/usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/bits/shared_ptr_base.h"
, 1055, __PRETTY_FUNCTION__, "_M_get() != nullptr"); } while (
false);
return *_M_get();
    }

    [[__deprecated__("shared_ptr<T[]>::operator-> is absent from C++17")]]
    element_type*
    operator->() const noexcept
    {
_GLIBCXX_DEBUG_PEDASSERT(_M_get() != nullptr);
return _M_get();
    }
1066#endif

    element_type&
    operator[](ptrdiff_t __i) const
    {
__glibcxx_assert(_M_get() != nullptr)do { if (! (_M_get() != nullptr)) std::__replacement_assert("/usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/bits/shared_ptr_base.h"
, 1071, __PRETTY_FUNCTION__, "_M_get() != nullptr"); } while (
false);
__glibcxx_assert(!extent<_Tp>::value || __i < extent<_Tp>::value)do { if (! (!extent<_Tp>::value || __i < extent<_Tp
>::value)) std::__replacement_assert("/usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/bits/shared_ptr_base.h"
, 1072, __PRETTY_FUNCTION__, "!extent<_Tp>::value || __i < extent<_Tp>::value"
); } while (false);
return _M_get()[__i];
    }

  private:
    element_type*
    _M_get() const noexcept
    { return static_cast<const __shared_ptr<_Tp, _Lp>*>(this)->get(); }
  };

template<typename _Tp, _Lock_policy _Lp>
  class __shared_ptr
  : public __shared_ptr_access<_Tp, _Lp>
  {
  public:
    using element_type = typename remove_extent<_Tp>::type;

  private:
    // Constraint for taking ownership of a pointer of type _Yp*:
    template<typename _Yp>
using _SafeConv
 = typename enable_if<__sp_is_constructible<_Tp, _Yp>::value>::type;

    // Constraint for construction from shared_ptr and weak_ptr:
    template<typename _Yp, typename _Res = void>
using _Compatible = typename
 enable_if<__sp_compatible_with<_Yp*, _Tp*>::value, _Res>::type;

    // Constraint for assignment from shared_ptr and weak_ptr:
    template<typename _Yp>
using _Assignable = _Compatible<_Yp, __shared_ptr&>;

    // Constraint for construction from unique_ptr:
    template<typename _Yp, typename _Del, typename _Res = void,
      typename _Ptr = typename unique_ptr<_Yp, _Del>::pointer>
using _UniqCompatible = typename enable_if<__and_<
 __sp_compatible_with<_Yp*, _Tp*>, is_convertible<_Ptr, element_type*>
 >::value, _Res>::type;

    // Constraint for assignment from unique_ptr:
    template<typename _Yp, typename _Del>
using _UniqAssignable = _UniqCompatible<_Yp, _Del, __shared_ptr&>;

  public:

1117#if __cplusplus201703L > 201402L
    using weak_type = __weak_ptr<_Tp, _Lp>;
1119#endif

    constexpr __shared_ptr() noexcept
    : _M_ptr(0), _M_refcount()
    { }

    template<typename _Yp, typename = _SafeConv<_Yp>>
explicit
__shared_ptr(_Yp* __p)
: _M_ptr(__p), _M_refcount(__p, typename is_array<_Tp>::type())
{
 static_assert( !is_void<_Yp>::value, "incomplete type" );
 static_assert( sizeof(_Yp) > 0, "incomplete type" );
 _M_enable_shared_from_this_with(__p);
}

    template<typename _Yp, typename _Deleter, typename = _SafeConv<_Yp>>
__shared_ptr(_Yp* __p, _Deleter __d)
: _M_ptr(__p), _M_refcount(__p, std::move(__d))
{
 static_assert(__is_invocable<_Deleter&, _Yp*&>::value,
     "deleter expression d(p) is well-formed");
 _M_enable_shared_from_this_with(__p);
}

    template<typename _Yp, typename _Deleter, typename _Alloc,
      typename = _SafeConv<_Yp>>
__shared_ptr(_Yp* __p, _Deleter __d, _Alloc __a)
: _M_ptr(__p), _M_refcount(__p, std::move(__d), std::move(__a))
{
 static_assert(__is_invocable<_Deleter&, _Yp*&>::value,
     "deleter expression d(p) is well-formed");
 _M_enable_shared_from_this_with(__p);
}

    template<typename _Deleter>
__shared_ptr(nullptr_t __p, _Deleter __d)
: _M_ptr(0), _M_refcount(__p, std::move(__d))
{ }

    template<typename _Deleter, typename _Alloc>
      __shared_ptr(nullptr_t __p, _Deleter __d, _Alloc __a)
: _M_ptr(0), _M_refcount(__p, std::move(__d), std::move(__a))
{ }

    // Aliasing constructor
    template<typename _Yp>
__shared_ptr(const __shared_ptr<_Yp, _Lp>& __r,
     element_type* __p) noexcept
: _M_ptr(__p), _M_refcount(__r._M_refcount) // never throws
{ }

    // Aliasing constructor
    template<typename _Yp>
__shared_ptr(__shared_ptr<_Yp, _Lp>&& __r,
     element_type* __p) noexcept
: _M_ptr(__p), _M_refcount()
{
 _M_refcount._M_swap(__r._M_refcount);
 __r._M_ptr = 0;
}

    __shared_ptr(const __shared_ptr&) noexcept = default;
    __shared_ptr& operator=(const __shared_ptr&) noexcept = default;
    ~__shared_ptr() = default;

    template<typename _Yp, typename = _Compatible<_Yp>>
__shared_ptr(const __shared_ptr<_Yp, _Lp>& __r) noexcept
: _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount)
{ }

    __shared_ptr(__shared_ptr&& __r) noexcept
    : _M_ptr(__r._M_ptr), _M_refcount()
    {
_M_refcount._M_swap(__r._M_refcount);
__r._M_ptr = 0;
    }

    template<typename _Yp, typename = _Compatible<_Yp>>
__shared_ptr(__shared_ptr<_Yp, _Lp>&& __r) noexcept
: _M_ptr(__r._M_ptr), _M_refcount()
{
 _M_refcount._M_swap(__r._M_refcount);
 __r._M_ptr = 0;
}

    template<typename _Yp, typename = _Compatible<_Yp>>
explicit __shared_ptr(const __weak_ptr<_Yp, _Lp>& __r)
: _M_refcount(__r._M_refcount) // may throw
{
 // It is now safe to copy __r._M_ptr, as
 // _M_refcount(__r._M_refcount) did not throw.
 _M_ptr = __r._M_ptr;
}

    // If an exception is thrown this constructor has no effect.
    template<typename _Yp, typename _Del,
      typename = _UniqCompatible<_Yp, _Del>>
__shared_ptr(unique_ptr<_Yp, _Del>&& __r)
: _M_ptr(__r.get()), _M_refcount()
{
 auto __raw = __to_address(__r.get());
 _M_refcount = __shared_count<_Lp>(std::move(__r));
 _M_enable_shared_from_this_with(__raw);
}

1225#if __cplusplus201703L <= 201402L && _GLIBCXX_USE_DEPRECATED1
  protected:
    // If an exception is thrown this constructor has no effect.
    template<typename _Tp1, typename _Del,
      typename enable_if<__and_<
 __not_<is_array<_Tp>>, is_array<_Tp1>,
        is_convertible<typename unique_ptr<_Tp1, _Del>::pointer, _Tp*>
      >::value, bool>::type = true>
__shared_ptr(unique_ptr<_Tp1, _Del>&& __r, __sp_array_delete)
: _M_ptr(__r.get()), _M_refcount()
{
 auto __raw = __to_address(__r.get());
 _M_refcount = __shared_count<_Lp>(std::move(__r));
 _M_enable_shared_from_this_with(__raw);
}
  public:
1241#endif

1243#if _GLIBCXX_USE_DEPRECATED1
1244#pragma GCC diagnostic push
1245#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
    // Postcondition: use_count() == 1 and __r.get() == 0
    template<typename _Yp, typename = _Compatible<_Yp>>
__shared_ptr(auto_ptr<_Yp>&& __r);
1249#pragma GCC diagnostic pop
1250#endif

    constexpr __shared_ptr(nullptr_t) noexcept : __shared_ptr() { }

    template<typename _Yp>
_Assignable<_Yp>
operator=(const __shared_ptr<_Yp, _Lp>& __r) noexcept
{
 _M_ptr = __r._M_ptr;
 _M_refcount = __r._M_refcount; // __shared_count::op= doesn't throw
 return *this;
}

1263#if _GLIBCXX_USE_DEPRECATED1
1264#pragma GCC diagnostic push
1265#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
    template<typename _Yp>
_Assignable<_Yp>
operator=(auto_ptr<_Yp>&& __r)
{
 __shared_ptr(std::move(__r)).swap(*this);
 return *this;
}
1273#pragma GCC diagnostic pop
1274#endif

    __shared_ptr&
    operator=(__shared_ptr&& __r) noexcept
    {
__shared_ptr(std::move(__r)).swap(*this);
return *this;
    }

    template<class _Yp>
_Assignable<_Yp>
operator=(__shared_ptr<_Yp, _Lp>&& __r) noexcept
{
 __shared_ptr(std::move(__r)).swap(*this);
 return *this;
}

    template<typename _Yp, typename _Del>
_UniqAssignable<_Yp, _Del>
operator=(unique_ptr<_Yp, _Del>&& __r)
{
 __shared_ptr(std::move(__r)).swap(*this);
 return *this;
}

    void
    reset() noexcept
    { __shared_ptr().swap(*this); }

    template<typename _Yp>
_SafeConv<_Yp>
reset(_Yp* __p) // _Yp must be complete.
{
 // Catch self-reset errors.
 __glibcxx_assert(__p == 0 || __p != _M_ptr)do { if (! (__p == 0 || __p != _M_ptr)) std::__replacement_assert
("/usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/bits/shared_ptr_base.h"
, 1308, __PRETTY_FUNCTION__, "__p == 0 || __p != _M_ptr"); } while
 (false);
 __shared_ptr(__p).swap(*this);
}

    template<typename _Yp, typename _Deleter>
_SafeConv<_Yp>
reset(_Yp* __p, _Deleter __d)
{ __shared_ptr(__p, std::move(__d)).swap(*this); }

    template<typename _Yp, typename _Deleter, typename _Alloc>
_SafeConv<_Yp>
reset(_Yp* __p, _Deleter __d, _Alloc __a)
      { __shared_ptr(__p, std::move(__d), std::move(__a)).swap(*this); }

    /// Return the stored pointer.
    element_type*
    get() const noexcept
    { return _M_ptr; }

    /// Return true if the stored pointer is not null.
    explicit operator bool() const // never throws
    { return _M_ptr == 0 ? false : true; }

    /// Return true if use_count() == 1.
    bool
    unique() const noexcept
    { return _M_refcount._M_unique(); }

    /// If *this owns a pointer, return the number of owners, otherwise zero.
    long
    use_count() const noexcept
    { return _M_refcount._M_get_use_count(); }

    /// Exchange both the owned pointer and the stored pointer.
    void
    swap(__shared_ptr<_Tp, _Lp>& __other) noexcept
    {
std::swap(_M_ptr, __other._M_ptr);
_M_refcount._M_swap(__other._M_refcount);
    }

    /** @brief Define an ordering based on ownership.
     *
     * This function defines a strict weak ordering between two shared_ptr
     * or weak_ptr objects, such that one object is less than the other
     * unless they share ownership of the same pointer, or are both empty.
     * @{
    */
    template<typename _Tp1>
bool
owner_before(__shared_ptr<_Tp1, _Lp> const& __rhs) const noexcept
{ return _M_refcount._M_less(__rhs._M_refcount); }

    template<typename _Tp1>
bool
owner_before(__weak_ptr<_Tp1, _Lp> const& __rhs) const noexcept
{ return _M_refcount._M_less(__rhs._M_refcount); }
    // @}

  protected:
    // This constructor is non-standard, it is used by allocate_shared.
    template<typename _Alloc, typename... _Args>
__shared_ptr(_Sp_alloc_shared_tag<_Alloc> __tag, _Args&&... __args)
: _M_ptr(), _M_refcount(_M_ptr, __tag, std::forward<_Args>(__args)...)
18
←
Calling constructor for '__shared_count<__gnu_cxx::_S_atomic>'→
28
←
Returning from constructor for '__shared_count<__gnu_cxx::_S_atomic>'→
{ _M_enable_shared_from_this_with(_M_ptr); }

    template<typename _Tp1, _Lock_policy _Lp1, typename _Alloc,
      typename... _Args>
friend __shared_ptr<_Tp1, _Lp1>
__allocate_shared(const _Alloc& __a, _Args&&... __args);

    // This constructor is used by __weak_ptr::lock() and
    // shared_ptr::shared_ptr(const weak_ptr&, std::nothrow_t).
    __shared_ptr(const __weak_ptr<_Tp, _Lp>& __r, std::nothrow_t)
    : _M_refcount(__r._M_refcount, std::nothrow)
    {
_M_ptr = _M_refcount._M_get_use_count() ? __r._M_ptr : nullptr;
    }

    friend class __weak_ptr<_Tp, _Lp>;

  private:

    template<typename _Yp>
using __esft_base_t = decltype(__enable_shared_from_this_base(
     std::declval<const __shared_count<_Lp>&>(),
     std::declval<_Yp*>()));

    // Detect an accessible and unambiguous enable_shared_from_this base.
    template<typename _Yp, typename = void>
struct __has_esft_base
: false_type { };

    template<typename _Yp>
struct __has_esft_base<_Yp, __void_t<__esft_base_t<_Yp>>>
: __not_<is_array<_Tp>> { }; // No enable shared_from_this for arrays

    template<typename _Yp, typename _Yp2 = typename remove_cv<_Yp>::type>
typename enable_if<__has_esft_base<_Yp2>::value>::type
_M_enable_shared_from_this_with(_Yp* __p) noexcept
{
 if (auto __base = __enable_shared_from_this_base(_M_refcount, __p))
   __base->_M_weak_assign(const_cast<_Yp2*>(__p), _M_refcount);
}

    template<typename _Yp, typename _Yp2 = typename remove_cv<_Yp>::type>
typename enable_if<!__has_esft_base<_Yp2>::value>::type
_M_enable_shared_from_this_with(_Yp*) noexcept
{ }

    void*
    _M_get_deleter(const std::type_info& __ti) const noexcept
    { return _M_refcount._M_get_deleter(__ti); }

    template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr;
    template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr;

    template<typename _Del, typename _Tp1, _Lock_policy _Lp1>
friend _Del* get_deleter(const __shared_ptr<_Tp1, _Lp1>&) noexcept;

    template<typename _Del, typename _Tp1>
friend _Del* get_deleter(const shared_ptr<_Tp1>&) noexcept;

    element_type*	   _M_ptr;         // Contained pointer.
    __shared_count<_Lp>  _M_refcount;    // Reference counter.
  };


// 20.7.2.2.7 shared_ptr comparisons
template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
  inline bool
  operator==(const __shared_ptr<_Tp1, _Lp>& __a,
      const __shared_ptr<_Tp2, _Lp>& __b) noexcept
  { return __a.get() == __b.get(); }

template<typename _Tp, _Lock_policy _Lp>
  inline bool
  operator==(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
  { return !__a; }

1448#ifdef __cpp_lib_three_way_comparison
template<typename _Tp, typename _Up, _Lock_policy _Lp>
  inline strong_ordering
  operator<=>(const __shared_ptr<_Tp, _Lp>& __a,
const __shared_ptr<_Up, _Lp>& __b) noexcept
  { return compare_three_way()(__a.get(), __b.get()); }

template<typename _Tp, _Lock_policy _Lp>
  inline strong_ordering
  operator<=>(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
  {
    using pointer = typename __shared_ptr<_Tp, _Lp>::element_type*;
    return compare_three_way()(__a.get(), static_cast<pointer>(nullptr));
  }
1462#else
template<typename _Tp, _Lock_policy _Lp>
  inline bool
  operator==(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
  { return !__a; }

template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
  inline bool
  operator!=(const __shared_ptr<_Tp1, _Lp>& __a,
      const __shared_ptr<_Tp2, _Lp>& __b) noexcept
  { return __a.get() != __b.get(); }

template<typename _Tp, _Lock_policy _Lp>
  inline bool
  operator!=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
  { return (bool)__a; }

template<typename _Tp, _Lock_policy _Lp>
  inline bool
  operator!=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
  { return (bool)__a; }

template<typename _Tp, typename _Up, _Lock_policy _Lp>
  inline bool
  operator<(const __shared_ptr<_Tp, _Lp>& __a,
     const __shared_ptr<_Up, _Lp>& __b) noexcept
  {
    using _Tp_elt = typename __shared_ptr<_Tp, _Lp>::element_type;
    using _Up_elt = typename __shared_ptr<_Up, _Lp>::element_type;
    using _Vp = typename common_type<_Tp_elt*, _Up_elt*>::type;
    return less<_Vp>()(__a.get(), __b.get());
  }

template<typename _Tp, _Lock_policy _Lp>
  inline bool
  operator<(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
  {
    using _Tp_elt = typename __shared_ptr<_Tp, _Lp>::element_type;
    return less<_Tp_elt*>()(__a.get(), nullptr);
  }

template<typename _Tp, _Lock_policy _Lp>
  inline bool
  operator<(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
  {
    using _Tp_elt = typename __shared_ptr<_Tp, _Lp>::element_type;
    return less<_Tp_elt*>()(nullptr, __a.get());
  }

template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
  inline bool
  operator<=(const __shared_ptr<_Tp1, _Lp>& __a,
      const __shared_ptr<_Tp2, _Lp>& __b) noexcept
  { return !(__b < __a); }

template<typename _Tp, _Lock_policy _Lp>
  inline bool
  operator<=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
  { return !(nullptr < __a); }

template<typename _Tp, _Lock_policy _Lp>
  inline bool
  operator<=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
  { return !(__a < nullptr); }

template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
  inline bool
  operator>(const __shared_ptr<_Tp1, _Lp>& __a,
     const __shared_ptr<_Tp2, _Lp>& __b) noexcept
  { return (__b < __a); }

template<typename _Tp, _Lock_policy _Lp>
  inline bool
  operator>(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
  { return nullptr < __a; }

template<typename _Tp, _Lock_policy _Lp>
  inline bool
  operator>(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
  { return __a < nullptr; }

template<typename _Tp1, typename _Tp2, _Lock_policy _Lp>
  inline bool
  operator>=(const __shared_ptr<_Tp1, _Lp>& __a,
      const __shared_ptr<_Tp2, _Lp>& __b) noexcept
  { return !(__a < __b); }

template<typename _Tp, _Lock_policy _Lp>
  inline bool
  operator>=(const __shared_ptr<_Tp, _Lp>& __a, nullptr_t) noexcept
  { return !(__a < nullptr); }

template<typename _Tp, _Lock_policy _Lp>
  inline bool
  operator>=(nullptr_t, const __shared_ptr<_Tp, _Lp>& __a) noexcept
  { return !(nullptr < __a); }
1558#endif // three-way comparison

// 20.7.2.2.8 shared_ptr specialized algorithms.
template<typename _Tp, _Lock_policy _Lp>
  inline void
  swap(__shared_ptr<_Tp, _Lp>& __a, __shared_ptr<_Tp, _Lp>& __b) noexcept
  { __a.swap(__b); }

// 20.7.2.2.9 shared_ptr casts

// The seemingly equivalent code:
// shared_ptr<_Tp, _Lp>(static_cast<_Tp*>(__r.get()))
// will eventually result in undefined behaviour, attempting to
// delete the same object twice.
/// static_pointer_cast
template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
  inline __shared_ptr<_Tp, _Lp>
  static_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
  {
    using _Sp = __shared_ptr<_Tp, _Lp>;
    return _Sp(__r, static_cast<typename _Sp::element_type*>(__r.get()));
  }

// The seemingly equivalent code:
// shared_ptr<_Tp, _Lp>(const_cast<_Tp*>(__r.get()))
// will eventually result in undefined behaviour, attempting to
// delete the same object twice.
/// const_pointer_cast
template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
  inline __shared_ptr<_Tp, _Lp>
  const_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
  {
    using _Sp = __shared_ptr<_Tp, _Lp>;
    return _Sp(__r, const_cast<typename _Sp::element_type*>(__r.get()));
  }

// The seemingly equivalent code:
// shared_ptr<_Tp, _Lp>(dynamic_cast<_Tp*>(__r.get()))
// will eventually result in undefined behaviour, attempting to
// delete the same object twice.
/// dynamic_pointer_cast
template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
  inline __shared_ptr<_Tp, _Lp>
  dynamic_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
  {
    using _Sp = __shared_ptr<_Tp, _Lp>;
    if (auto* __p = dynamic_cast<typename _Sp::element_type*>(__r.get()))
return _Sp(__r, __p);
    return _Sp();
  }

1609#if __cplusplus201703L > 201402L
template<typename _Tp, typename _Tp1, _Lock_policy _Lp>
  inline __shared_ptr<_Tp, _Lp>
  reinterpret_pointer_cast(const __shared_ptr<_Tp1, _Lp>& __r) noexcept
  {
    using _Sp = __shared_ptr<_Tp, _Lp>;
    return _Sp(__r, reinterpret_cast<typename _Sp::element_type*>(__r.get()));
  }
1617#endif

template<typename _Tp, _Lock_policy _Lp>
  class __weak_ptr
  {
    template<typename _Yp, typename _Res = void>
using _Compatible = typename
 enable_if<__sp_compatible_with<_Yp*, _Tp*>::value, _Res>::type;

    // Constraint for assignment from shared_ptr and weak_ptr:
    template<typename _Yp>
using _Assignable = _Compatible<_Yp, __weak_ptr&>;

  public:
    using element_type = typename remove_extent<_Tp>::type;

    constexpr __weak_ptr() noexcept
    : _M_ptr(nullptr), _M_refcount()
    { }

    __weak_ptr(const __weak_ptr&) noexcept = default;

    ~__weak_ptr() = default;

    // The "obvious" converting constructor implementation:
    //
    //  template<typename _Tp1>
    //    __weak_ptr(const __weak_ptr<_Tp1, _Lp>& __r)
    //    : _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount) // never throws
    //    { }
    //
    // has a serious problem.
    //
    //  __r._M_ptr may already have been invalidated. The _M_ptr(__r._M_ptr)
    //  conversion may require access to *__r._M_ptr (virtual inheritance).
    //
    // It is not possible to avoid spurious access violations since
    // in multithreaded programs __r._M_ptr may be invalidated at any point.
    template<typename _Yp, typename = _Compatible<_Yp>>
__weak_ptr(const __weak_ptr<_Yp, _Lp>& __r) noexcept
: _M_refcount(__r._M_refcount)
      { _M_ptr = __r.lock().get(); }

    template<typename _Yp, typename = _Compatible<_Yp>>
__weak_ptr(const __shared_ptr<_Yp, _Lp>& __r) noexcept
: _M_ptr(__r._M_ptr), _M_refcount(__r._M_refcount)
{ }

    __weak_ptr(__weak_ptr&& __r) noexcept
    : _M_ptr(__r._M_ptr), _M_refcount(std::move(__r._M_refcount))
    { __r._M_ptr = nullptr; }

    template<typename _Yp, typename = _Compatible<_Yp>>
__weak_ptr(__weak_ptr<_Yp, _Lp>&& __r) noexcept
: _M_ptr(__r.lock().get()), _M_refcount(std::move(__r._M_refcount))
      { __r._M_ptr = nullptr; }

    __weak_ptr&
    operator=(const __weak_ptr& __r) noexcept = default;

    template<typename _Yp>
_Assignable<_Yp>
operator=(const __weak_ptr<_Yp, _Lp>& __r) noexcept
{
 _M_ptr = __r.lock().get();
 _M_refcount = __r._M_refcount;
 return *this;
}

    template<typename _Yp>
_Assignable<_Yp>
operator=(const __shared_ptr<_Yp, _Lp>& __r) noexcept
{
 _M_ptr = __r._M_ptr;
 _M_refcount = __r._M_refcount;
 return *this;
}

    __weak_ptr&
    operator=(__weak_ptr&& __r) noexcept
    {
_M_ptr = __r._M_ptr;
_M_refcount = std::move(__r._M_refcount);
__r._M_ptr = nullptr;
return *this;
    }

    template<typename _Yp>
_Assignable<_Yp>
operator=(__weak_ptr<_Yp, _Lp>&& __r) noexcept
{
 _M_ptr = __r.lock().get();
 _M_refcount = std::move(__r._M_refcount);
 __r._M_ptr = nullptr;
 return *this;
}

    __shared_ptr<_Tp, _Lp>
    lock() const noexcept
    { return __shared_ptr<element_type, _Lp>(*this, std::nothrow); }

    long
    use_count() const noexcept
    { return _M_refcount._M_get_use_count(); }

    bool
    expired() const noexcept
    { return _M_refcount._M_get_use_count() == 0; }

    template<typename _Tp1>
bool
owner_before(const __shared_ptr<_Tp1, _Lp>& __rhs) const noexcept
{ return _M_refcount._M_less(__rhs._M_refcount); }

    template<typename _Tp1>
bool
owner_before(const __weak_ptr<_Tp1, _Lp>& __rhs) const noexcept
{ return _M_refcount._M_less(__rhs._M_refcount); }

    void
    reset() noexcept
    { __weak_ptr().swap(*this); }

    void
    swap(__weak_ptr& __s) noexcept
    {
std::swap(_M_ptr, __s._M_ptr);
_M_refcount._M_swap(__s._M_refcount);
    }

  private:
    // Used by __enable_shared_from_this.
    void
    _M_assign(_Tp* __ptr, const __shared_count<_Lp>& __refcount) noexcept
    {
if (use_count() == 0)
 {
   _M_ptr = __ptr;
   _M_refcount = __refcount;
 }
    }

    template<typename _Tp1, _Lock_policy _Lp1> friend class __shared_ptr;
    template<typename _Tp1, _Lock_policy _Lp1> friend class __weak_ptr;
    friend class __enable_shared_from_this<_Tp, _Lp>;
    friend class enable_shared_from_this<_Tp>;

    element_type*	 _M_ptr;         // Contained pointer.
    __weak_count<_Lp>  _M_refcount;    // Reference counter.
  };

// 20.7.2.3.6 weak_ptr specialized algorithms.
template<typename _Tp, _Lock_policy _Lp>
  inline void
  swap(__weak_ptr<_Tp, _Lp>& __a, __weak_ptr<_Tp, _Lp>& __b) noexcept
  { __a.swap(__b); }

template<typename _Tp, typename _Tp1>
  struct _Sp_owner_less : public binary_function<_Tp, _Tp, bool>
  {
    bool
    operator()(const _Tp& __lhs, const _Tp& __rhs) const noexcept
    { return __lhs.owner_before(__rhs); }

    bool
    operator()(const _Tp& __lhs, const _Tp1& __rhs) const noexcept
    { return __lhs.owner_before(__rhs); }

    bool
    operator()(const _Tp1& __lhs, const _Tp& __rhs) const noexcept
    { return __lhs.owner_before(__rhs); }
  };

template<>
  struct _Sp_owner_less<void, void>
  {
    template<typename _Tp, typename _Up>
auto
operator()(const _Tp& __lhs, const _Up& __rhs) const noexcept
-> decltype(__lhs.owner_before(__rhs))
{ return __lhs.owner_before(__rhs); }

    using is_transparent = void;
  };

template<typename _Tp, _Lock_policy _Lp>
  struct owner_less<__shared_ptr<_Tp, _Lp>>
  : public _Sp_owner_less<__shared_ptr<_Tp, _Lp>, __weak_ptr<_Tp, _Lp>>
  { };

template<typename _Tp, _Lock_policy _Lp>
  struct owner_less<__weak_ptr<_Tp, _Lp>>
  : public _Sp_owner_less<__weak_ptr<_Tp, _Lp>, __shared_ptr<_Tp, _Lp>>
  { };


template<typename _Tp, _Lock_policy _Lp>
  class __enable_shared_from_this
  {
  protected:
    constexpr __enable_shared_from_this() noexcept { }

    __enable_shared_from_this(const __enable_shared_from_this&) noexcept { }

    __enable_shared_from_this&
    operator=(const __enable_shared_from_this&) noexcept
    { return *this; }

    ~__enable_shared_from_this() { }

  public:
    __shared_ptr<_Tp, _Lp>
    shared_from_this()
    { return __shared_ptr<_Tp, _Lp>(this->_M_weak_this); }

    __shared_ptr<const _Tp, _Lp>
    shared_from_this() const
    { return __shared_ptr<const _Tp, _Lp>(this->_M_weak_this); }

1836#if __cplusplus201703L > 201402L || !defined(__STRICT_ANSI__1) // c++1z or gnu++11
    __weak_ptr<_Tp, _Lp>
    weak_from_this() noexcept
    { return this->_M_weak_this; }

    __weak_ptr<const _Tp, _Lp>
    weak_from_this() const noexcept
    { return this->_M_weak_this; }
1844#endif

  private:
    template<typename _Tp1>
void
_M_weak_assign(_Tp1* __p, const __shared_count<_Lp>& __n) const noexcept
{ _M_weak_this._M_assign(__p, __n); }

    friend const __enable_shared_from_this*
    __enable_shared_from_this_base(const __shared_count<_Lp>&,
		     const __enable_shared_from_this* __p)
    { return __p; }

    template<typename, _Lock_policy>
friend class __shared_ptr;

    mutable __weak_ptr<_Tp, _Lp>  _M_weak_this;
  };

template<typename _Tp, _Lock_policy _Lp = __default_lock_policy,
  typename _Alloc, typename... _Args>
  inline __shared_ptr<_Tp, _Lp>
  __allocate_shared(const _Alloc& __a, _Args&&... __args)
  {
    return __shared_ptr<_Tp, _Lp>(_Sp_alloc_shared_tag<_Alloc>{__a},
		    std::forward<_Args>(__args)...);
  }

template<typename _Tp, _Lock_policy _Lp = __default_lock_policy,
  typename... _Args>
  inline __shared_ptr<_Tp, _Lp>
  __make_shared(_Args&&... __args)
  {
    typedef typename std::remove_const<_Tp>::type _Tp_nc;
    return std::__allocate_shared<_Tp, _Lp>(std::allocator<_Tp_nc>(),
			      std::forward<_Args>(__args)...);
  }

/// std::hash specialization for __shared_ptr.
template<typename _Tp, _Lock_policy _Lp>
  struct hash<__shared_ptr<_Tp, _Lp>>
  : public __hash_base<size_t, __shared_ptr<_Tp, _Lp>>
  {
    size_t
    operator()(const __shared_ptr<_Tp, _Lp>& __s) const noexcept
    {
return hash<typename __shared_ptr<_Tp, _Lp>::element_type*>()(
   __s.get());
    }
  };

1895_GLIBCXX_END_NAMESPACE_VERSION
1896} // namespace

1898#endif // _SHARED_PTR_BASE_H

←

/usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/bits/allocated_ptr.h

→

1// Guarded Allocation -*- C++ -*-
2 
3// Copyright (C) 2014-2020 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library.  This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.
10 
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14// GNU General Public License for more details.
15 
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19 
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
23// <http://www.gnu.org/licenses/>.
24 
25/** @file bits/allocated_ptr.h
26 *  This is an internal header file, included by other library headers.
27 *  Do not attempt to use it directly. @headername{memory}
28 */
29 
30#ifndef _ALLOCATED_PTR_H1
31#define _ALLOCATED_PTR_H1 1
32 
33#if __cplusplus201703L < 201103L
34# include <bits/c++0xwarning.h>
35#else
36# include <type_traits>
37# include <bits/ptr_traits.h>
38# include <bits/alloc_traits.h>
39 
40namespace std _GLIBCXX_VISIBILITY(default)__attribute__ ((__visibility__ ("default")))
41{
42_GLIBCXX_BEGIN_NAMESPACE_VERSION
43 
44  /// Non-standard RAII type for managing pointers obtained from allocators.
45  template<typename _Alloc>
46    struct __allocated_ptr
47    {
48      using pointer = typename allocator_traits<_Alloc>::pointer;
49      using value_type = typename allocator_traits<_Alloc>::value_type;
50 
51      /// Take ownership of __ptr
52      __allocated_ptr(_Alloc& __a, pointer __ptr) noexcept
53      : _M_alloc(std::__addressof(__a)), _M_ptr(__ptr)
54      { }
55 
56      /// Convert __ptr to allocator's pointer type and take ownership of it
57      template<typename _Ptr,
58	       typename _Req = _Require<is_same<_Ptr, value_type*>>>
59      __allocated_ptr(_Alloc& __a, _Ptr __ptr)
60      : _M_alloc(std::__addressof(__a)),
61	_M_ptr(pointer_traits<pointer>::pointer_to(*__ptr))
62      { }
63 
64      /// Transfer ownership of the owned pointer
65      __allocated_ptr(__allocated_ptr&& __gd) noexcept
66      : _M_alloc(__gd._M_alloc), _M_ptr(__gd._M_ptr)
67      { __gd._M_ptr = nullptr; }
68 
69      /// Deallocate the owned pointer
70      ~__allocated_ptr()
71      {
72	if (_M_ptr != nullptr)
73	  std::allocator_traits<_Alloc>::deallocate(*_M_alloc, _M_ptr, 1);
74      }
75 
76      /// Release ownership of the owned pointer
77      __allocated_ptr&
78      operator=(std::nullptr_t) noexcept
79      {
80	_M_ptr = nullptr;
81	return *this;
82      }
83 
84      /// Get the address that the owned pointer refers to.
85      value_type* get() { return std::__to_address(_M_ptr); }
86 
87    private:
88      _Alloc* _M_alloc;
89      pointer _M_ptr;
90    };
91 
92  /// Allocate space for a single object using __a
93  template<typename _Alloc>
94    __allocated_ptr<_Alloc>
95    __allocate_guarded(_Alloc& __a)
96    {
97      return { __a, std::allocator_traits<_Alloc>::allocate(__a, 1) };
20
←
Calling 'allocator_traits::allocate'→
26
←
Returned allocated memory→
98    }
99 
100_GLIBCXX_END_NAMESPACE_VERSION
101} // namespace std
102 
103#endif
104#endif

←

/usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/bits/alloc_traits.h

→

1// Allocator traits -*- C++ -*-

3// Copyright (C) 2011-2020 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library.  This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.

11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14// GNU General Public License for more details.

16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.

20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
23// <http://www.gnu.org/licenses/>.

25/** @file bits/alloc_traits.h
*  This is an internal header file, included by other library headers.
*  Do not attempt to use it directly. @headername{memory}
*/

30#ifndef _ALLOC_TRAITS_H1
31#define _ALLOC_TRAITS_H1 1

33#include <bits/stl_construct.h>
34#include <bits/memoryfwd.h>
35#if __cplusplus201703L >= 201103L
36# include <bits/allocator.h>
37# include <bits/ptr_traits.h>
38# include <ext/numeric_traits.h>
39#endif

41namespace std _GLIBCXX_VISIBILITY(default)__attribute__ ((__visibility__ ("default")))
42{
43_GLIBCXX_BEGIN_NAMESPACE_VERSION

45#if __cplusplus201703L >= 201103L
46#define __cpp_lib_allocator_traits_is_always_equal201411 201411

struct __allocator_traits_base
{
  template<typename _Tp, typename _Up, typename = void>
    struct __rebind : __replace_first_arg<_Tp, _Up> { };

  template<typename _Tp, typename _Up>
    struct __rebind<_Tp, _Up,
      __void_t<typename _Tp::template rebind<_Up>::other>>
    { using type = typename _Tp::template rebind<_Up>::other; };

protected:
  template<typename _Tp>
    using __pointer = typename _Tp::pointer;
  template<typename _Tp>
    using __c_pointer = typename _Tp::const_pointer;
  template<typename _Tp>
    using __v_pointer = typename _Tp::void_pointer;
  template<typename _Tp>
    using __cv_pointer = typename _Tp::const_void_pointer;
  template<typename _Tp>
    using __pocca = typename _Tp::propagate_on_container_copy_assignment;
  template<typename _Tp>
    using __pocma = typename _Tp::propagate_on_container_move_assignment;
  template<typename _Tp>
    using __pocs = typename _Tp::propagate_on_container_swap;
  template<typename _Tp>
    using __equal = typename _Tp::is_always_equal;
};

template<typename _Alloc, typename _Up>
  using __alloc_rebind
    = typename __allocator_traits_base::template __rebind<_Alloc, _Up>::type;

/**
 * @brief  Uniform interface to all allocator types.
 * @ingroup allocators
*/
template<typename _Alloc>
  struct allocator_traits : __allocator_traits_base
  {
    /// The allocator type
    typedef _Alloc allocator_type;
    /// The allocated type
    typedef typename _Alloc::value_type value_type;

    /**
     * @brief   The allocator's pointer type.
     *
     * @c Alloc::pointer if that type exists, otherwise @c value_type*
    */
    using pointer = __detected_or_t<value_type*, __pointer, _Alloc>;

  private:
    // Select _Func<_Alloc> or pointer_traits<pointer>::rebind<_Tp>
    template<template<typename> class _Func, typename _Tp, typename = void>
struct _Ptr
{
 using type = typename pointer_traits<pointer>::template rebind<_Tp>;
};

    template<template<typename> class _Func, typename _Tp>
struct _Ptr<_Func, _Tp, __void_t<_Func<_Alloc>>>
{
 using type = _Func<_Alloc>;
};

    // Select _A2::difference_type or pointer_traits<_Ptr>::difference_type
    template<typename _A2, typename _PtrT, typename = void>
struct _Diff
{ using type = typename pointer_traits<_PtrT>::difference_type; };

    template<typename _A2, typename _PtrT>
struct _Diff<_A2, _PtrT, __void_t<typename _A2::difference_type>>
{ using type = typename _A2::difference_type; };

    // Select _A2::size_type or make_unsigned<_DiffT>::type
    template<typename _A2, typename _DiffT, typename = void>
struct _Size : make_unsigned<_DiffT> { };

    template<typename _A2, typename _DiffT>
struct _Size<_A2, _DiffT, __void_t<typename _A2::size_type>>
{ using type = typename _A2::size_type; };

  public:
    /**
     * @brief   The allocator's const pointer type.
     *
     * @c Alloc::const_pointer if that type exists, otherwise
     * <tt> pointer_traits<pointer>::rebind<const value_type> </tt>
    */
    using const_pointer = typename _Ptr<__c_pointer, const value_type>::type;

    /**
     * @brief   The allocator's void pointer type.
     *
     * @c Alloc::void_pointer if that type exists, otherwise
     * <tt> pointer_traits<pointer>::rebind<void> </tt>
    */
    using void_pointer = typename _Ptr<__v_pointer, void>::type;

    /**
     * @brief   The allocator's const void pointer type.
     *
     * @c Alloc::const_void_pointer if that type exists, otherwise
     * <tt> pointer_traits<pointer>::rebind<const void> </tt>
    */
    using const_void_pointer = typename _Ptr<__cv_pointer, const void>::type;

    /**
     * @brief   The allocator's difference type
     *
     * @c Alloc::difference_type if that type exists, otherwise
     * <tt> pointer_traits<pointer>::difference_type </tt>
    */
    using difference_type = typename _Diff<_Alloc, pointer>::type;

    /**
     * @brief   The allocator's size type
     *
     * @c Alloc::size_type if that type exists, otherwise
     * <tt> make_unsigned<difference_type>::type </tt>
    */
    using size_type = typename _Size<_Alloc, difference_type>::type;

    /**
     * @brief   How the allocator is propagated on copy assignment
     *
     * @c Alloc::propagate_on_container_copy_assignment if that type exists,
     * otherwise @c false_type
    */
    using propagate_on_container_copy_assignment
= __detected_or_t<false_type, __pocca, _Alloc>;

    /**
     * @brief   How the allocator is propagated on move assignment
     *
     * @c Alloc::propagate_on_container_move_assignment if that type exists,
     * otherwise @c false_type
    */
    using propagate_on_container_move_assignment
= __detected_or_t<false_type, __pocma, _Alloc>;

    /**
     * @brief   How the allocator is propagated on swap
     *
     * @c Alloc::propagate_on_container_swap if that type exists,
     * otherwise @c false_type
    */
    using propagate_on_container_swap
= __detected_or_t<false_type, __pocs, _Alloc>;

    /**
     * @brief   Whether all instances of the allocator type compare equal.
     *
     * @c Alloc::is_always_equal if that type exists,
     * otherwise @c is_empty<Alloc>::type
    */
    using is_always_equal
= __detected_or_t<typename is_empty<_Alloc>::type, __equal, _Alloc>;

    template<typename _Tp>
using rebind_alloc = __alloc_rebind<_Alloc, _Tp>;
    template<typename _Tp>
using rebind_traits = allocator_traits<rebind_alloc<_Tp>>;

  private:
    template<typename _Alloc2>
static constexpr auto
_S_allocate(_Alloc2& __a, size_type __n, const_void_pointer __hint, int)
-> decltype(__a.allocate(__n, __hint))
{ return __a.allocate(__n, __hint); }

    template<typename _Alloc2>
static constexpr pointer
_S_allocate(_Alloc2& __a, size_type __n, const_void_pointer, ...)
{ return __a.allocate(__n); }

    template<typename _Tp, typename... _Args>
struct __construct_helper
{
 template<typename _Alloc2,
   typename = decltype(std::declval<_Alloc2*>()->construct(
  std::declval<_Tp*>(), std::declval<_Args>()...))>
   static true_type __test(int);

 template<typename>
   static false_type __test(...);

 using type = decltype(__test<_Alloc>(0));
};

    template<typename _Tp, typename... _Args>
using __has_construct
 = typename __construct_helper<_Tp, _Args...>::type;

    template<typename _Tp, typename... _Args>
static _GLIBCXX14_CONSTEXPRconstexpr _Require<__has_construct<_Tp, _Args...>>
_S_construct(_Alloc& __a, _Tp* __p, _Args&&... __args)
noexcept(noexcept(__a.construct(__p, std::forward<_Args>(__args)...)))
{ __a.construct(__p, std::forward<_Args>(__args)...); }

    template<typename _Tp, typename... _Args>
static _GLIBCXX14_CONSTEXPRconstexpr
_Require<__and_<__not_<__has_construct<_Tp, _Args...>>,
	       is_constructible<_Tp, _Args...>>>
_S_construct(_Alloc&, _Tp* __p, _Args&&... __args)
noexcept(std::is_nothrow_constructible<_Tp, _Args...>::value)
{
256#if __cplusplus201703L <= 201703L
 ::new((void*)__p) _Tp(std::forward<_Args>(__args)...);
258#else
 std::construct_at(__p, std::forward<_Args>(__args)...);
260#endif
}

    template<typename _Alloc2, typename _Tp>
static _GLIBCXX14_CONSTEXPRconstexpr auto
_S_destroy(_Alloc2& __a, _Tp* __p, int)
noexcept(noexcept(__a.destroy(__p)))
-> decltype(__a.destroy(__p))
{ __a.destroy(__p); }

    template<typename _Alloc2, typename _Tp>
static _GLIBCXX14_CONSTEXPRconstexpr void
_S_destroy(_Alloc2&, _Tp* __p, ...)
noexcept(std::is_nothrow_destructible<_Tp>::value)
{ std::_Destroy(__p); }

    template<typename _Alloc2>
static constexpr auto
_S_max_size(_Alloc2& __a, int)
-> decltype(__a.max_size())
{ return __a.max_size(); }

    template<typename _Alloc2>
static constexpr size_type
_S_max_size(_Alloc2&, ...)
{
 // _GLIBCXX_RESOLVE_LIB_DEFECTS
 // 2466. allocator_traits::max_size() default behavior is incorrect
 return __gnu_cxx::__numeric_traits<size_type>::__max
   / sizeof(value_type);
}

    template<typename _Alloc2>
static constexpr auto
_S_select(_Alloc2& __a, int)
-> decltype(__a.select_on_container_copy_construction())
{ return __a.select_on_container_copy_construction(); }

    template<typename _Alloc2>
static constexpr _Alloc2
_S_select(_Alloc2& __a, ...)
{ return __a; }

  public:

    /**
     *  @brief  Allocate memory.
     *  @param  __a  An allocator.
     *  @param  __n  The number of objects to allocate space for.
     *
     *  Calls @c a.allocate(n)
    */
    _GLIBCXX_NODISCARD[[__nodiscard__]] static _GLIBCXX20_CONSTEXPR pointer
    allocate(_Alloc& __a, size_type __n)
    { return __a.allocate(__n); }

    /**
     *  @brief  Allocate memory.
     *  @param  __a  An allocator.
     *  @param  __n  The number of objects to allocate space for.
     *  @param  __hint Aid to locality.
     *  @return Memory of suitable size and alignment for @a n objects
     *          of type @c value_type
     *
     *  Returns <tt> a.allocate(n, hint) </tt> if that expression is
     *  well-formed, otherwise returns @c a.allocate(n)
    */
    _GLIBCXX_NODISCARD[[__nodiscard__]] static _GLIBCXX20_CONSTEXPR pointer
    allocate(_Alloc& __a, size_type __n, const_void_pointer __hint)
    { return _S_allocate(__a, __n, __hint, 0); }

    /**
     *  @brief  Deallocate memory.
     *  @param  __a  An allocator.
     *  @param  __p  Pointer to the memory to deallocate.
     *  @param  __n  The number of objects space was allocated for.
     *
     *  Calls <tt> a.deallocate(p, n) </tt>
    */
    static _GLIBCXX20_CONSTEXPR void
    deallocate(_Alloc& __a, pointer __p, size_type __n)
    { __a.deallocate(__p, __n); }

    /**
     *  @brief  Construct an object of type @a _Tp
     *  @param  __a  An allocator.
     *  @param  __p  Pointer to memory of suitable size and alignment for Tp
     *  @param  __args Constructor arguments.
     *
     *  Calls <tt> __a.construct(__p, std::forward<Args>(__args)...) </tt>
     *  if that expression is well-formed, otherwise uses placement-new
     *  to construct an object of type @a _Tp at location @a __p from the
     *  arguments @a __args...
    */
    template<typename _Tp, typename... _Args>
static _GLIBCXX20_CONSTEXPR auto
construct(_Alloc& __a, _Tp* __p, _Args&&... __args)
noexcept(noexcept(_S_construct(__a, __p,
		       std::forward<_Args>(__args)...)))
-> decltype(_S_construct(__a, __p, std::forward<_Args>(__args)...))
{ _S_construct(__a, __p, std::forward<_Args>(__args)...); }

    /**
     *  @brief  Destroy an object of type @a _Tp
     *  @param  __a  An allocator.
     *  @param  __p  Pointer to the object to destroy
     *
     *  Calls @c __a.destroy(__p) if that expression is well-formed,
     *  otherwise calls @c __p->~_Tp()
    */
    template<typename _Tp>
static _GLIBCXX20_CONSTEXPR void
destroy(_Alloc& __a, _Tp* __p)
noexcept(noexcept(_S_destroy(__a, __p, 0)))
{ _S_destroy(__a, __p, 0); }

    /**
     *  @brief  The maximum supported allocation size
     *  @param  __a  An allocator.
     *  @return @c __a.max_size() or @c numeric_limits<size_type>::max()
     *
     *  Returns @c __a.max_size() if that expression is well-formed,
     *  otherwise returns @c numeric_limits<size_type>::max()
    */
    static _GLIBCXX20_CONSTEXPR size_type
    max_size(const _Alloc& __a) noexcept
    { return _S_max_size(__a, 0); }

    /**
     *  @brief  Obtain an allocator to use when copying a container.
     *  @param  __rhs  An allocator.
     *  @return @c __rhs.select_on_container_copy_construction() or @a __rhs
     *
     *  Returns @c __rhs.select_on_container_copy_construction() if that
     *  expression is well-formed, otherwise returns @a __rhs
    */
    static _GLIBCXX20_CONSTEXPR _Alloc
    select_on_container_copy_construction(const _Alloc& __rhs)
    { return _S_select(__rhs, 0); }
  };

401#if __cplusplus201703L > 201703L
402# define __cpp_lib_constexpr_dynamic_alloc 201907L
403#endif

/// Partial specialization for std::allocator.
template<typename _Tp>
  struct allocator_traits<allocator<_Tp>>
  {
    /// The allocator type
    using allocator_type = allocator<_Tp>;

    /// The allocated type
    using value_type = _Tp;

    /// The allocator's pointer type.
    using pointer = _Tp*;

    /// The allocator's const pointer type.
    using const_pointer = const _Tp*;

    /// The allocator's void pointer type.
    using void_pointer = void*;

    /// The allocator's const void pointer type.
    using const_void_pointer = const void*;

    /// The allocator's difference type
    using difference_type = std::ptrdiff_t;

    /// The allocator's size type
    using size_type = std::size_t;

    /// How the allocator is propagated on copy assignment
    using propagate_on_container_copy_assignment = false_type;

    /// How the allocator is propagated on move assignment
    using propagate_on_container_move_assignment = true_type;

    /// How the allocator is propagated on swap
    using propagate_on_container_swap = false_type;

    /// Whether all instances of the allocator type compare equal.
    using is_always_equal = true_type;

    template<typename _Up>
using rebind_alloc = allocator<_Up>;

    template<typename _Up>
using rebind_traits = allocator_traits<allocator<_Up>>;

    /**
     *  @brief  Allocate memory.
     *  @param  __a  An allocator.
     *  @param  __n  The number of objects to allocate space for.
     *
     *  Calls @c a.allocate(n)
    */
    _GLIBCXX_NODISCARD[[__nodiscard__]] static _GLIBCXX20_CONSTEXPR pointer
    allocate(allocator_type& __a, size_type __n)
    { return __a.allocate(__n); }
21
←
Calling 'new_allocator::allocate'→
25
←
Returned allocated memory→

    /**
     *  @brief  Allocate memory.
     *  @param  __a  An allocator.
     *  @param  __n  The number of objects to allocate space for.
     *  @param  __hint Aid to locality.
     *  @return Memory of suitable size and alignment for @a n objects
     *          of type @c value_type
     *
     *  Returns <tt> a.allocate(n, hint) </tt>
    */
    _GLIBCXX_NODISCARD[[__nodiscard__]] static _GLIBCXX20_CONSTEXPR pointer
    allocate(allocator_type& __a, size_type __n, const_void_pointer __hint)
    {
475#if __cplusplus201703L <= 201703L
return __a.allocate(__n, __hint);
477#else
return __a.allocate(__n);
479#endif
    }

    /**
     *  @brief  Deallocate memory.
     *  @param  __a  An allocator.
     *  @param  __p  Pointer to the memory to deallocate.
     *  @param  __n  The number of objects space was allocated for.
     *
     *  Calls <tt> a.deallocate(p, n) </tt>
    */
    static _GLIBCXX20_CONSTEXPR void
    deallocate(allocator_type& __a, pointer __p, size_type __n)
    { __a.deallocate(__p, __n); }

    /**
     *  @brief  Construct an object of type `_Up`
     *  @param  __a  An allocator.
     *  @param  __p  Pointer to memory of suitable size and alignment for
     *	       an object of type `_Up`.
     *  @param  __args Constructor arguments.
     *
     *  Calls `__a.construct(__p, std::forward<_Args>(__args)...)`
     *  in C++11, C++14 and C++17. Changed in C++20 to call
     *  `std::construct_at(__p, std::forward<_Args>(__args)...)` instead.
    */
    template<typename _Up, typename... _Args>
static _GLIBCXX20_CONSTEXPR void
construct(allocator_type& __a __attribute__((__unused__)), _Up* __p,
  _Args&&... __args)
noexcept(std::is_nothrow_constructible<_Up, _Args...>::value)
{
511#if __cplusplus201703L <= 201703L
 __a.construct(__p, std::forward<_Args>(__args)...);
513#else
 std::construct_at(__p, std::forward<_Args>(__args)...);
515#endif
}

    /**
     *  @brief  Destroy an object of type @a _Up
     *  @param  __a  An allocator.
     *  @param  __p  Pointer to the object to destroy
     *
     *  Calls @c __a.destroy(__p).
    */
    template<typename _Up>
static _GLIBCXX20_CONSTEXPR void
destroy(allocator_type& __a __attribute__((__unused__)), _Up* __p)
noexcept(is_nothrow_destructible<_Up>::value)
{
530#if __cplusplus201703L <= 201703L
 __a.destroy(__p);
532#else
 std::destroy_at(__p);
534#endif
}

    /**
     *  @brief  The maximum supported allocation size
     *  @param  __a  An allocator.
     *  @return @c __a.max_size()
    */
    static _GLIBCXX20_CONSTEXPR size_type
    max_size(const allocator_type& __a __attribute__((__unused__))) noexcept
    {
545#if __cplusplus201703L <= 201703L
return __a.max_size();
547#else
return size_t(-1) / sizeof(value_type);
549#endif
    }

    /**
     *  @brief  Obtain an allocator to use when copying a container.
     *  @param  __rhs  An allocator.
     *  @return @c __rhs
    */
    static _GLIBCXX20_CONSTEXPR allocator_type
    select_on_container_copy_construction(const allocator_type& __rhs)
    { return __rhs; }
  };

562#if __cplusplus201703L < 201703L
template<typename _Alloc>
  inline void
  __do_alloc_on_copy(_Alloc& __one, const _Alloc& __two, true_type)
  { __one = __two; }

template<typename _Alloc>
  inline void
  __do_alloc_on_copy(_Alloc&, const _Alloc&, false_type)
  { }
572#endif

template<typename _Alloc>
  _GLIBCXX14_CONSTEXPRconstexpr inline void
  __alloc_on_copy(_Alloc& __one, const _Alloc& __two)
  {
    typedef allocator_traits<_Alloc> __traits;
    typedef typename __traits::propagate_on_container_copy_assignment __pocca;
580#if __cplusplus201703L >= 201703L
    if constexpr (__pocca::value)
__one = __two;
583#else
    __do_alloc_on_copy(__one, __two, __pocca());
585#endif
  }

template<typename _Alloc>
  constexpr _Alloc
  __alloc_on_copy(const _Alloc& __a)
  {
    typedef allocator_traits<_Alloc> __traits;
    return __traits::select_on_container_copy_construction(__a);
  }

596#if __cplusplus201703L < 201703L
template<typename _Alloc>
  inline void __do_alloc_on_move(_Alloc& __one, _Alloc& __two, true_type)
  { __one = std::move(__two); }

template<typename _Alloc>
  inline void __do_alloc_on_move(_Alloc&, _Alloc&, false_type)
  { }
604#endif

template<typename _Alloc>
  _GLIBCXX14_CONSTEXPRconstexpr inline void
  __alloc_on_move(_Alloc& __one, _Alloc& __two)
  {
    typedef allocator_traits<_Alloc> __traits;
    typedef typename __traits::propagate_on_container_move_assignment __pocma;
612#if __cplusplus201703L >= 201703L
    if constexpr (__pocma::value)
__one = std::move(__two);
615#else
    __do_alloc_on_move(__one, __two, __pocma());
617#endif
  }

620#if __cplusplus201703L < 201703L
template<typename _Alloc>
  inline void __do_alloc_on_swap(_Alloc& __one, _Alloc& __two, true_type)
  {
    using std::swap;
    swap(__one, __two);
  }

template<typename _Alloc>
  inline void __do_alloc_on_swap(_Alloc&, _Alloc&, false_type)
  { }
631#endif

template<typename _Alloc>
  _GLIBCXX14_CONSTEXPRconstexpr inline void
  __alloc_on_swap(_Alloc& __one, _Alloc& __two)
  {
    typedef allocator_traits<_Alloc> __traits;
    typedef typename __traits::propagate_on_container_swap __pocs;
639#if __cplusplus201703L >= 201703L
    if constexpr (__pocs::value)
{
 using std::swap;
 swap(__one, __two);
}
645#else
    __do_alloc_on_swap(__one, __two, __pocs());
647#endif
  }

template<typename _Alloc, typename _Tp,
  typename _ValueT = __remove_cvref_t<typename _Alloc::value_type>,
  typename = void>
  struct __is_alloc_insertable_impl
  : false_type
  { };

template<typename _Alloc, typename _Tp, typename _ValueT>
  struct __is_alloc_insertable_impl<_Alloc, _Tp, _ValueT,
    __void_t<decltype(allocator_traits<_Alloc>::construct(
   std::declval<_Alloc&>(), std::declval<_ValueT*>(),
   std::declval<_Tp>()))>>
  : true_type
  { };

// true if _Alloc::value_type is CopyInsertable into containers using _Alloc
// (might be wrong if _Alloc::construct exists but is not constrained,
// i.e. actually trying to use it would still be invalid. Use with caution.)
template<typename _Alloc>
  struct __is_copy_insertable
  : __is_alloc_insertable_impl<_Alloc,
		 typename _Alloc::value_type const&>::type
  { };

// std::allocator<_Tp> just requires CopyConstructible
template<typename _Tp>
  struct __is_copy_insertable<allocator<_Tp>>
  : is_copy_constructible<_Tp>
  { };

// true if _Alloc::value_type is MoveInsertable into containers using _Alloc
// (might be wrong if _Alloc::construct exists but is not constrained,
// i.e. actually trying to use it would still be invalid. Use with caution.)
template<typename _Alloc>
  struct __is_move_insertable
  : __is_alloc_insertable_impl<_Alloc, typename _Alloc::value_type>::type
  { };

// std::allocator<_Tp> just requires MoveConstructible
template<typename _Tp>
  struct __is_move_insertable<allocator<_Tp>>
  : is_move_constructible<_Tp>
  { };

// Trait to detect Allocator-like types.
template<typename _Alloc, typename = void>
  struct __is_allocator : false_type { };

template<typename _Alloc>
  struct __is_allocator<_Alloc,
    __void_t<typename _Alloc::value_type,
      decltype(std::declval<_Alloc&>().allocate(size_t{}))>>
  : true_type { };

template<typename _Alloc>
  using _RequireAllocator
    = typename enable_if<__is_allocator<_Alloc>::value, _Alloc>::type;

template<typename _Alloc>
  using _RequireNotAllocator
    = typename enable_if<!__is_allocator<_Alloc>::value, _Alloc>::type;
711#endif // C++11

/**
 * Destroy a range of objects using the supplied allocator.  For
 * non-default allocators we do not optimize away invocation of
 * destroy() even if _Tp has a trivial destructor.
 */

template<typename _ForwardIterator, typename _Allocator>
  void
  _Destroy(_ForwardIterator __first, _ForwardIterator __last,
    _Allocator& __alloc)
  {
    for (; __first != __last; ++__first)
725#if __cplusplus201703L < 201103L
__alloc.destroy(std::__addressof(*__first));
727#else
allocator_traits<_Allocator>::destroy(__alloc,
			      std::__addressof(*__first));
730#endif
  }

template<typename _ForwardIterator, typename _Tp>
  inline void
  _Destroy(_ForwardIterator __first, _ForwardIterator __last,
    allocator<_Tp>&)
  {
    _Destroy(__first, __last);
  }

741_GLIBCXX_END_NAMESPACE_VERSION
742} // namespace std
743#endif // _ALLOC_TRAITS_H

←

/usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/ext/new_allocator.h

1// Allocator that wraps operator new -*- C++ -*-
2 
3// Copyright (C) 2001-2020 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library.  This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.
10 
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14// GNU General Public License for more details.
15 
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19 
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
23// <http://www.gnu.org/licenses/>.
24 
25/** @file ext/new_allocator.h
26 *  This file is a GNU extension to the Standard C++ Library.
27 */
28 
29#ifndef _NEW_ALLOCATOR_H1
30#define _NEW_ALLOCATOR_H1 1
31 
32#include <bits/c++config.h>
33#include <new>
34#include <bits/functexcept.h>
35#include <bits/move.h>
36#if __cplusplus201703L >= 201103L
37#include <type_traits>
38#endif
39 
40namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)__attribute__ ((__visibility__ ("default")))
41{
42_GLIBCXX_BEGIN_NAMESPACE_VERSION
43 
44  /**
45   *  @brief  An allocator that uses global new, as per [20.4].
46   *  @ingroup allocators
47   *
48   *  This is precisely the allocator defined in the C++ Standard.
49   *    - all allocation calls operator new
50   *    - all deallocation calls operator delete
51   *
52   *  @tparam  _Tp  Type of allocated object.
53   */
54  template<typename _Tp>
55    class new_allocator
56    {
57    public:
58      typedef _Tp        value_type;
59      typedef std::size_t     size_type;
60      typedef std::ptrdiff_t  difference_type;
61#if __cplusplus201703L <= 201703L
62      typedef _Tp*       pointer;
63      typedef const _Tp* const_pointer;
64      typedef _Tp&       reference;
65      typedef const _Tp& const_reference;
66 
67      template<typename _Tp1>
68	struct rebind
69	{ typedef new_allocator<_Tp1> other; };
70#endif
71 
72#if __cplusplus201703L >= 201103L
73      // _GLIBCXX_RESOLVE_LIB_DEFECTS
74      // 2103. propagate_on_container_move_assignment
75      typedef std::true_type propagate_on_container_move_assignment;
76#endif
77 
78      _GLIBCXX20_CONSTEXPR
79      new_allocator() _GLIBCXX_USE_NOEXCEPTnoexcept { }
80 
81      _GLIBCXX20_CONSTEXPR
82      new_allocator(const new_allocator&) _GLIBCXX_USE_NOEXCEPTnoexcept { }
83 
84      template<typename _Tp1>
85	_GLIBCXX20_CONSTEXPR
86	new_allocator(const new_allocator<_Tp1>&) _GLIBCXX_USE_NOEXCEPTnoexcept { }
87 
88#if __cplusplus201703L <= 201703L
89      ~new_allocator() _GLIBCXX_USE_NOEXCEPTnoexcept { }
90 
91      pointer
92      address(reference __x) const _GLIBCXX_NOEXCEPTnoexcept
93      { return std::__addressof(__x); }
94 
95      const_pointer
96      address(const_reference __x) const _GLIBCXX_NOEXCEPTnoexcept
97      { return std::__addressof(__x); }
98#endif
99 
100      // NB: __n is permitted to be 0.  The C++ standard says nothing
101      // about what the return value is when __n == 0.
102      _GLIBCXX_NODISCARD[[__nodiscard__]] _Tp*
103      allocate(size_type __n, const void* = static_cast<const void*>(0))
104      {
105	if (__n > this->_M_max_size())
22
←
Taking false branch→
106	  std::__throw_bad_alloc();
107 
108#if __cpp_aligned_new201606L
109	if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__16UL)
23
←
Taking false branch→
110	  {
111	    std::align_val_t __al = std::align_val_t(alignof(_Tp));
112	    return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp), __al));
113	  }
114#endif
115	return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp)));
24
←
Memory is allocated→
116      }
117 
118      // __p is not permitted to be a null pointer.
119      void
120      deallocate(_Tp* __p, size_type __t)
121      {
122#if __cpp_aligned_new201606L
123	if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__16UL)
124	  {
125	    ::operator delete(__p,
126# if __cpp_sized_deallocation
127			      __t * sizeof(_Tp),
128# endif
129			      std::align_val_t(alignof(_Tp)));
130	    return;
131	  }
132#endif
133	::operator delete(__p
134#if __cpp_sized_deallocation
135			  , __t * sizeof(_Tp)
136#endif
137			 );
138      }
139 
140#if __cplusplus201703L <= 201703L
141      size_type
142      max_size() const _GLIBCXX_USE_NOEXCEPTnoexcept
143      { return _M_max_size(); }
144 
145#if __cplusplus201703L >= 201103L
146      template<typename _Up, typename... _Args>
147	void
148	construct(_Up* __p, _Args&&... __args)
149	noexcept(std::is_nothrow_constructible<_Up, _Args...>::value)
150	{ ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
151 
152      template<typename _Up>
153	void
154	destroy(_Up* __p)
155	noexcept(std::is_nothrow_destructible<_Up>::value)
156	{ __p->~_Up(); }
157#else
158      // _GLIBCXX_RESOLVE_LIB_DEFECTS
159      // 402. wrong new expression in [some_] allocator::construct
160      void
161      construct(pointer __p, const _Tp& __val)
162      { ::new((void *)__p) _Tp(__val); }
163 
164      void
165      destroy(pointer __p) { __p->~_Tp(); }
166#endif
167#endif // ! C++20
168 
169      template<typename _Up>
170	friend _GLIBCXX20_CONSTEXPR bool
171	operator==(const new_allocator&, const new_allocator<_Up>&)
172	_GLIBCXX_NOTHROWnoexcept
173	{ return true; }
174 
175#if __cpp_impl_three_way_comparison < 201907L
176      template<typename _Up>
177	friend _GLIBCXX20_CONSTEXPR bool
178	operator!=(const new_allocator&, const new_allocator<_Up>&)
179	_GLIBCXX_NOTHROWnoexcept
180	{ return false; }
181#endif
182 
183    private:
184      _GLIBCXX_CONSTEXPRconstexpr size_type
185      _M_max_size() const _GLIBCXX_USE_NOEXCEPTnoexcept
186      {
187#if __PTRDIFF_MAX__9223372036854775807L < __SIZE_MAX__18446744073709551615UL
188	return std::size_t(__PTRDIFF_MAX__9223372036854775807L) / sizeof(_Tp);
189#else
190	return std::size_t(-1) / sizeof(_Tp);
191#endif
192      }
193    };
194 
195_GLIBCXX_END_NAMESPACE_VERSION
196} // namespace
197 
198#endif