Export of internal Abseil changes

--
330051e00cd57ee516b4eaf656965656ffbcd0bc by Abseil Team <absl-team@google.com>:

Fix indentation in comment.

PiperOrigin-RevId: 287997504

--
35fb1a893e708031ba4fc0db460875eb0d31820e by Abseil Team <absl-team@google.com>:

Enable compile-time enforcement that absl::Substitute patterns to not contain unescaped $ symbols.

absl::Substitute already considers unescaped $ symbols undefined behavior and crashes when it's passed them in debug builds.  Some code isn't ever built in debug mode, though, and inadvertently used some unescaped $ symbols, which led to surprising results.  This change will prevent that problem from happening in the future.
PiperOrigin-RevId: 287906643

--
c5762833ebde6d7110bf68041a823b571c238e9e by Gennadiy Rozental <rogeeff@google.com>:

Move all the flag data into a single place instead of being split between handle and flag object.

After this change CommandLineFlag will not hold any data anymore. And we also do not need to pass the CommandLineFlag around in Abseil Flag implementation to report flag name and location.

PiperOrigin-RevId: 287899076

--
8b5fb644f1e3d9267b7a75106fe9a72c886db786 by Derek Mauro <dmauro@google.com>:

Upgrade CI testing to Bazel 2.0.0 and Clang 407ac2eb5f13

-fno-sanitize-blacklist is to workaround
https://github.com/bazelbuild/bazel/issues/10510

PiperOrigin-RevId: 287875363

--
a20cc1d58895de2babc3748a6c79d1d6813734ef by Abseil Team <absl-team@google.com>:

Make ABSL_RETIRED_FLAG behave consistently with ABSL_FLAG.

Before the change:
ABSL_RETIRED_FLAG does not compile when there are competing ctors in the type, even when ABSL_FLAG does.

After the change:
ABSL_RETIRED_FLAG compiles when ABSL_FLAG does.

PiperOrigin-RevId: 286483183

--
1cff7e67329d2be9e50bee1f2e76ef9ffd2edde5 by Abseil Team <absl-team@google.com>:

Support C++20 erase_if API in unordered associative containers

See [unord.set.erasure]: https://eel.is/c++draft/unord.set.erasure
See [unord.map.erasure]: https://eel.is/c++draft/unord.map.erasure

PiperOrigin-RevId: 286461140
GitOrigin-RevId: 330051e00cd57ee516b4eaf656965656ffbcd0bc
Change-Id: I5513110b41c2af08a44da54612cff341ac5c6607

9 files changed, 117 insertions, 219 deletions

diff --git a/absl/flags/BUILD.bazel b/absl/flags/BUILD.bazel
index cf4491985548..504acde8624b 100644
--- a/absl/flags/BUILD.bazel
+++ b/absl/flags/BUILD.bazel
@@ -38,6 +38,7 @@ cc_library(
     linkopts = ABSL_DEFAULT_LINKOPTS,
     visibility = ["//visibility:private"],
     deps = [
+        ":config",
         ":handle",
         ":registry",
         "//absl/base:core_headers",
@@ -121,9 +122,6 @@ cc_library(
 
 cc_library(
     name = "handle",
-    srcs = [
-        "internal/commandlineflag.cc",
-    ],
     hdrs = [
         "internal/commandlineflag.h",
     ],
diff --git a/absl/flags/CMakeLists.txt b/absl/flags/CMakeLists.txt
index 3a7162f9347b..7c63821e13eb 100644
--- a/absl/flags/CMakeLists.txt
+++ b/absl/flags/CMakeLists.txt
@@ -27,6 +27,7 @@ absl_cc_library(
   LINKOPTS
     ${ABSL_DEFAULT_LINKOPTS}
   DEPS
+    absl::flags_config
     absl::flags_handle
     absl::flags_registry
     absl::synchronization
@@ -108,8 +109,6 @@ absl_cc_library(
 absl_cc_library(
   NAME
     flags_handle
-  SRCS
-    "internal/commandlineflag.cc"
   HDRS
     "internal/commandlineflag.h"
   COPTS
diff --git a/absl/flags/flag.h b/absl/flags/flag.h
index f18e9f56a5cc..326fb8ee6894 100644
--- a/absl/flags/flag.h
+++ b/absl/flags/flag.h
@@ -94,14 +94,14 @@ class Flag {
   // Visual Studio 2015 still requires the constructor for class to be
   // constexpr initializable.
 #if _MSC_VER <= 1900
-  constexpr Flag(const char* name, const flags_internal::HelpGenFunc help_gen,
-                 const char* filename,
+  constexpr Flag(const char* name, const char* filename,
                  const flags_internal::FlagMarshallingOpFn marshalling_op,
+                 const flags_internal::HelpGenFunc help_gen,
                  const flags_internal::FlagDfltGenFunc default_value_gen)
       : name_(name),
-        help_gen_(help_gen),
         filename_(filename),
         marshalling_op_(marshalling_op),
+        help_gen_(help_gen),
         default_value_gen_(default_value_gen),
         inited_(false),
         impl_(nullptr) {}
@@ -116,10 +116,10 @@ class Flag {
       }
 
       impl_ = new flags_internal::Flag<T>(
-          name_,
+          name_, filename_, marshalling_op_,
           {flags_internal::FlagHelpSrc(help_gen_),
            flags_internal::FlagHelpSrcKind::kGenFunc},
-          filename_, marshalling_op_, default_value_gen_);
+          default_value_gen_);
       inited_.store(true, std::memory_order_release);
     }
 
@@ -155,9 +155,9 @@ class Flag {
   // The data members are logically private, but they need to be public for
   // this to be an aggregate type.
   const char* name_;
-  const flags_internal::HelpGenFunc help_gen_;
   const char* filename_;
   const flags_internal::FlagMarshallingOpFn marshalling_op_;
+  const flags_internal::HelpGenFunc help_gen_;
   const flags_internal::FlagDfltGenFunc default_value_gen_;
 
   mutable std::atomic<bool> inited_;
@@ -342,26 +342,24 @@ ABSL_NAMESPACE_END
   ABSL_FLAG_IMPL_DECLARE_DEF_VAL_WRAPPER(name, Type, default_value) \
   ABSL_FLAG_IMPL_DECLARE_HELP_WRAPPER(name, help);                  \
   ABSL_CONST_INIT absl::Flag<Type> FLAGS_##name{                    \
-      ABSL_FLAG_IMPL_FLAGNAME(#name),                               \
-      absl::flags_internal::HelpArg<AbslFlagHelpGenFor##name>(0),   \
-      ABSL_FLAG_IMPL_FILENAME(),                                    \
+      ABSL_FLAG_IMPL_FLAGNAME(#name), ABSL_FLAG_IMPL_FILENAME(),    \
       &absl::flags_internal::FlagMarshallingOps<Type>,              \
+      absl::flags_internal::HelpArg<AbslFlagHelpGenFor##name>(0),   \
       &AbslFlagsInitFlag##name};                                    \
   extern bool FLAGS_no##name;                                       \
   bool FLAGS_no##name = ABSL_FLAG_IMPL_REGISTRAR(Type, FLAGS_##name)
 #else
 // MSVC version uses aggregate initialization. We also do not try to
 // optimize away help wrapper.
-#define ABSL_FLAG_IMPL(Type, name, default_value, help)                    \
-  namespace absl /* block flags in namespaces */ {}                        \
-  ABSL_FLAG_IMPL_DECLARE_DEF_VAL_WRAPPER(name, Type, default_value)        \
-  ABSL_FLAG_IMPL_DECLARE_HELP_WRAPPER(name, help);                         \
-  ABSL_CONST_INIT absl::Flag<Type> FLAGS_##name{                           \
-      ABSL_FLAG_IMPL_FLAGNAME(#name), &AbslFlagHelpGenFor##name::NonConst, \
-      ABSL_FLAG_IMPL_FILENAME(),                                           \
-      &absl::flags_internal::FlagMarshallingOps<Type>,                     \
-      &AbslFlagsInitFlag##name};                                           \
-  extern bool FLAGS_no##name;                                              \
+#define ABSL_FLAG_IMPL(Type, name, default_value, help)               \
+  namespace absl /* block flags in namespaces */ {}                   \
+  ABSL_FLAG_IMPL_DECLARE_DEF_VAL_WRAPPER(name, Type, default_value)   \
+  ABSL_FLAG_IMPL_DECLARE_HELP_WRAPPER(name, help);                    \
+  ABSL_CONST_INIT absl::Flag<Type> FLAGS_##name{                      \
+      ABSL_FLAG_IMPL_FLAGNAME(#name), ABSL_FLAG_IMPL_FILENAME(),      \
+      &absl::flags_internal::FlagMarshallingOps<Type>,                \
+      &AbslFlagHelpGenFor##name::NonConst, &AbslFlagsInitFlag##name}; \
+  extern bool FLAGS_no##name;                                         \
   bool FLAGS_no##name = ABSL_FLAG_IMPL_REGISTRAR(Type, FLAGS_##name)
 #endif
 
@@ -384,19 +382,11 @@ ABSL_NAMESPACE_END
 //
 // `default_value` is only used as a double check on the type. `explanation` is
 // unused.
-//
-// ABSL_RETIRED_FLAG support omitting the default value for default
-// constructible value type, so that users can delete the code generatring this
-// value.
-//
 // TODO(rogeeff): Return an anonymous struct instead of bool, and place it into
 // the unnamed namespace.
 #define ABSL_RETIRED_FLAG(type, flagname, default_value, explanation) \
-  ABSL_ATTRIBUTE_UNUSED static const bool ignored_##flagname =             \
-      ([] {                                                                \
-           return absl::flags_internal::MakeFromDefaultValueOrEmpty<type>( \
-                   default_value);                                         \
-       },                                                                  \
+  ABSL_ATTRIBUTE_UNUSED static const bool ignored_##flagname =        \
+      ([] { return type(default_value); },                            \
        absl::flags_internal::RetiredFlag<type>(#flagname))
 
 #endif  // ABSL_FLAGS_FLAG_H_
diff --git a/absl/flags/flag_test.cc b/absl/flags/flag_test.cc
index 465f018c5e4f..28c513b020a8 100644
--- a/absl/flags/flag_test.cc
+++ b/absl/flags/flag_test.cc
@@ -43,16 +43,16 @@ template <typename T>
 bool TestConstructionFor() {
   constexpr flags::HelpInitArg help_arg{flags::FlagHelpSrc("literal help"),
                                         flags::FlagHelpSrcKind::kLiteral};
-  constexpr flags::Flag<T> f1("f1", help_arg, "file",
-                              &flags::FlagMarshallingOps<T>, &TestMakeDflt<T>);
+  constexpr flags::Flag<T> f1("f1", "file", &flags::FlagMarshallingOps<T>,
+                              help_arg, &TestMakeDflt<T>);
   EXPECT_EQ(f1.Name(), "f1");
   EXPECT_EQ(f1.Help(), "literal help");
   EXPECT_EQ(f1.Filename(), "file");
 
   ABSL_CONST_INIT static flags::Flag<T> f2(
-      "f2",
+      "f2", "file", &flags::FlagMarshallingOps<T>,
       {flags::FlagHelpSrc(&TestHelpMsg), flags::FlagHelpSrcKind::kGenFunc},
-      "file", &flags::FlagMarshallingOps<T>, &TestMakeDflt<T>);
+      &TestMakeDflt<T>);
   flags::FlagRegistrar<T, false>(&f2).OnUpdate(TestCallback);
 
   EXPECT_EQ(f2.Name(), "f2");
@@ -486,30 +486,11 @@ TEST_F(FlagTest, TestNonDefaultConstructibleType) {
 
 // --------------------------------------------------------------------
 
-struct Wrapper {
-  Wrapper() {}
-
-  // NOLINTNEXTLINE(runtime/explicit)
-  Wrapper(const std::string& val) : val(val) {}
-
-  // NOLINTNEXTLINE(runtime/explicit)
-  template <typename T>
-  Wrapper(T&& t) : val(std::forward<T>(t)) {}
-
-  // NOLINTNEXTLINE(runtime/explicit)
-  operator std::string() const& { return val; }
-
-  std::string val;
-};
-
 }  // namespace
 
 ABSL_RETIRED_FLAG(bool, old_bool_flag, true, "old descr");
 ABSL_RETIRED_FLAG(int, old_int_flag, (int)std::sqrt(10), "old descr");
 ABSL_RETIRED_FLAG(std::string, old_str_flag, "", absl::StrCat("old ", "descr"));
-ABSL_RETIRED_FLAG(Wrapper, old_wrapper_flag, {}, "old wrapper");
-ABSL_RETIRED_FLAG(Wrapper, old_wrapper_no_default_flag, ,
-                  "old wrapper no default");
 
 namespace {
 
@@ -521,10 +502,6 @@ TEST_F(FlagTest, TestRetiredFlagRegistration) {
   EXPECT_FALSE(is_bool);
   EXPECT_TRUE(flags::IsRetiredFlag("old_str_flag", &is_bool));
   EXPECT_FALSE(is_bool);
-  EXPECT_TRUE(flags::IsRetiredFlag("old_wrapper_flag", &is_bool));
-  EXPECT_FALSE(is_bool);
-  EXPECT_TRUE(flags::IsRetiredFlag("old_wrapper_no_default_flag", &is_bool));
-  EXPECT_FALSE(is_bool);
   EXPECT_FALSE(flags::IsRetiredFlag("some_other_flag", &is_bool));
 }
 
diff --git a/absl/flags/internal/commandlineflag.cc b/absl/flags/internal/commandlineflag.cc
deleted file mode 100644
index 09249274c3e7..000000000000
--- a/absl/flags/internal/commandlineflag.cc
+++ /dev/null
@@ -1,62 +0,0 @@
-//
-// Copyright 2019 The Abseil Authors.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//      https://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-#include "absl/flags/internal/commandlineflag.h"
-
-#include "absl/flags/usage_config.h"
-
-namespace absl {
-ABSL_NAMESPACE_BEGIN
-namespace flags_internal {
-
-// The help message indicating that the commandline flag has been
-// 'stripped'. It will not show up when doing "-help" and its
-// variants. The flag is stripped if ABSL_FLAGS_STRIP_HELP is set to 1
-// before including absl/flags/flag.h
-
-// This is used by this file, and also in commandlineflags_reporting.cc
-const char kStrippedFlagHelp[] = "\001\002\003\004 (unknown) \004\003\002\001";
-
-absl::string_view CommandLineFlag::Typename() const {
-  // We do not store/report type in Abseil Flags, so that user do not rely on in
-  // at runtime
-  if (IsAbseilFlag() || IsRetired()) return "";
-
-#define HANDLE_V1_BUILTIN_TYPE(t) \
-  if (IsOfType<t>()) {            \
-    return #t;                    \
-  }
-
-  HANDLE_V1_BUILTIN_TYPE(bool);
-  HANDLE_V1_BUILTIN_TYPE(int32_t);
-  HANDLE_V1_BUILTIN_TYPE(int64_t);
-  HANDLE_V1_BUILTIN_TYPE(uint64_t);
-  HANDLE_V1_BUILTIN_TYPE(double);
-#undef HANDLE_V1_BUILTIN_TYPE
-
-  if (IsOfType<std::string>()) {
-    return "string";
-  }
-
-  return "";
-}
-
-std::string CommandLineFlag::Filename() const {
-  return flags_internal::GetUsageConfig().normalize_filename(filename_);
-}
-
-}  // namespace flags_internal
-ABSL_NAMESPACE_END
-}  // namespace absl
diff --git a/absl/flags/internal/commandlineflag.h b/absl/flags/internal/commandlineflag.h
index 49e13d1e726b..a0c18e80b6c7 100644
--- a/absl/flags/internal/commandlineflag.h
+++ b/absl/flags/internal/commandlineflag.h
@@ -61,8 +61,6 @@ enum ValueSource {
   kProgrammaticChange,
 };
 
-extern const char kStrippedFlagHelp[];
-
 // The per-type function
 template <typename T>
 void* FlagOps(FlagOp op, const void* v1, void* v2) {
@@ -155,8 +153,7 @@ class FlagStateInterface {
 // Holds all information for a flag.
 class CommandLineFlag {
  public:
-  constexpr CommandLineFlag(const char* name, const char* filename)
-      : name_(name), filename_(filename) {}
+  constexpr CommandLineFlag() = default;
 
   // Virtual destructor
   virtual void Destroy() = 0;
@@ -166,9 +163,6 @@ class CommandLineFlag {
   CommandLineFlag& operator=(const CommandLineFlag&) = delete;
 
   // Non-polymorphic access methods.
-  absl::string_view Name() const { return name_; }
-  absl::string_view Typename() const;
-  std::string Filename() const;
 
   // Return true iff flag has type T.
   template <typename T>
@@ -190,8 +184,7 @@ class CommandLineFlag {
     //
     //  1. `U.value` has correct size and alignment for a value of type `T`
     //  2. The `U.value` constructor is not invoked since U's constructor does
-    //  not
-    //     do it explicitly.
+    //     not do it explicitly.
     //  3. The `U.value` destructor is invoked since U's destructor does it
     //     explicitly. This makes `U` a kind of RAII wrapper around non default
     //     constructible value of T, which is destructed when we leave the
@@ -213,9 +206,16 @@ class CommandLineFlag {
 
   // Polymorphic access methods
 
-  // Returns help message associated with this flag
+  // Returns name of this flag.
+  virtual absl::string_view Name() const = 0;
+  // Returns name of the file where this flag is defined.
+  virtual std::string Filename() const = 0;
+  // Returns name of the flag's value type for some built-in types or empty
+  // std::string.
+  virtual absl::string_view Typename() const = 0;
+  // Returns help message associated with this flag.
   virtual std::string Help() const = 0;
-  // Returns true iff this object corresponds to retired flag
+  // Returns true iff this object corresponds to retired flag.
   virtual bool IsRetired() const { return false; }
   // Returns true iff this is a handle to an Abseil Flag.
   virtual bool IsAbseilFlag() const { return true; }
@@ -253,10 +253,6 @@ class CommandLineFlag {
  protected:
   ~CommandLineFlag() = default;
 
-  // Constant configuration for a particular flag.
-  const char* const name_;      // Flags name passed to ABSL_FLAG as second arg.
-  const char* const filename_;  // The file name where ABSL_FLAG resides.
-
  private:
   // Copy-construct a new value of the flag's type in a memory referenced by
   // the dst based on the current flag's value.
diff --git a/absl/flags/internal/flag.cc b/absl/flags/internal/flag.cc
index 599bd7a45561..bb9a98f34404 100644
--- a/absl/flags/internal/flag.cc
+++ b/absl/flags/internal/flag.cc
@@ -16,17 +16,25 @@
 #include "absl/flags/internal/flag.h"
 
 #include "absl/base/optimization.h"
+#include "absl/flags/usage_config.h"
 #include "absl/synchronization/mutex.h"
 
 namespace absl {
 ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
+
+// The help message indicating that the commandline flag has been
+// 'stripped'. It will not show up when doing "-help" and its
+// variants. The flag is stripped if ABSL_FLAGS_STRIP_HELP is set to 1
+// before including absl/flags/flag.h
+const char kStrippedFlagHelp[] = "\001\002\003\004 (unknown) \004\003\002\001";
+
 namespace {
 
 // Currently we only validate flag values for user-defined flag types.
-bool ShouldValidateFlagValue(const CommandLineFlag& flag) {
+bool ShouldValidateFlagValue(FlagOpFn flag_type_id) {
 #define DONT_VALIDATE(T) \
-  if (flag.IsOfType<T>()) return false;
+  if (flag_type_id == &flags_internal::FlagOps<T>) return false;
   ABSL_FLAGS_INTERNAL_FOR_EACH_LOCK_FREE(DONT_VALIDATE)
   DONT_VALIDATE(std::string)
   DONT_VALIDATE(std::vector<std::string>)
@@ -123,6 +131,12 @@ std::unique_ptr<void, DynValueDeleter> FlagImpl::MakeInitValue() const {
   return {res, DynValueDeleter{op_}};
 }
 
+absl::string_view FlagImpl::Name() const { return name_; }
+
+std::string FlagImpl::Filename() const {
+  return flags_internal::GetUsageConfig().normalize_filename(filename_);
+}
+
 std::string FlagImpl::Help() const {
   return help_source_kind_ == FlagHelpSrcKind::kLiteral ? help_.literal
                                                         : help_.gen_func();
@@ -186,16 +200,15 @@ void FlagImpl::InvokeCallback() const {
   cb();
 }
 
-bool FlagImpl::RestoreState(const CommandLineFlag& flag, const void* value,
-                            bool modified, bool on_command_line,
-                            int64_t counter) {
+bool FlagImpl::RestoreState(const void* value, bool modified,
+                            bool on_command_line, int64_t counter) {
   {
     absl::MutexLock l(DataGuard());
 
     if (counter_ == counter) return false;
   }
 
-  Write(flag, value, op_);
+  Write(value, op_);
 
   {
     absl::MutexLock l(DataGuard());
@@ -211,18 +224,15 @@ bool FlagImpl::RestoreState(const CommandLineFlag& flag, const void* value,
 // argument. If parsing successful, this function replaces the dst with newly
 // parsed value. In case if any error is encountered in either step, the error
 // message is stored in 'err'
-bool FlagImpl::TryParse(const CommandLineFlag& flag, void** dst,
-                        absl::string_view value, std::string* err) const {
+bool FlagImpl::TryParse(void** dst, absl::string_view value,
+                        std::string* err) const {
   auto tentative_value = MakeInitValue();
 
   std::string parse_err;
   if (!Parse(marshalling_op_, value, tentative_value.get(), &parse_err)) {
-    auto type_name = flag.Typename();
     absl::string_view err_sep = parse_err.empty() ? "" : "; ";
-    absl::string_view typename_sep = type_name.empty() ? "" : " ";
-    *err = absl::StrCat("Illegal value '", value, "' specified for",
-                        typename_sep, type_name, " flag '", flag.Name(), "'",
-                        err_sep, parse_err);
+    *err = absl::StrCat("Illegal value '", value, "' specified for flag '",
+                        Name(), "'", err_sep, parse_err);
     return false;
   }
 
@@ -233,8 +243,7 @@ bool FlagImpl::TryParse(const CommandLineFlag& flag, void** dst,
   return true;
 }
 
-void FlagImpl::Read(const CommandLineFlag& flag, void* dst,
-                    const flags_internal::FlagOpFn dst_op) const {
+void FlagImpl::Read(void* dst, const flags_internal::FlagOpFn dst_op) const {
   absl::ReaderMutexLock l(DataGuard());
 
   // `dst_op` is the unmarshaling operation corresponding to the declaration
@@ -243,7 +252,7 @@ void FlagImpl::Read(const CommandLineFlag& flag, void* dst,
   if (ABSL_PREDICT_FALSE(dst_op != op_)) {
     ABSL_INTERNAL_LOG(
         ERROR,
-        absl::StrCat("Flag '", flag.Name(),
+        absl::StrCat("Flag '", Name(),
                      "' is defined as one type and declared as another"));
   }
   CopyConstruct(op_, cur_, dst);
@@ -259,8 +268,7 @@ void FlagImpl::StoreAtomic() {
   }
 }
 
-void FlagImpl::Write(const CommandLineFlag& flag, const void* src,
-                     const flags_internal::FlagOpFn src_op) {
+void FlagImpl::Write(const void* src, const flags_internal::FlagOpFn src_op) {
   absl::MutexLock l(DataGuard());
 
   // `src_op` is the marshalling operation corresponding to the declaration
@@ -269,18 +277,17 @@ void FlagImpl::Write(const CommandLineFlag& flag, const void* src,
   if (ABSL_PREDICT_FALSE(src_op != op_)) {
     ABSL_INTERNAL_LOG(
         ERROR,
-        absl::StrCat("Flag '", flag.Name(),
+        absl::StrCat("Flag '", Name(),
                      "' is defined as one type and declared as another"));
   }
 
-  if (ShouldValidateFlagValue(flag)) {
+  if (ShouldValidateFlagValue(op_)) {
     void* obj = Clone(op_, src);
     std::string ignored_error;
     std::string src_as_str = Unparse(marshalling_op_, src);
     if (!Parse(marshalling_op_, src_as_str, obj, &ignored_error)) {
-      ABSL_INTERNAL_LOG(ERROR,
-                        absl::StrCat("Attempt to set flag '", flag.Name(),
-                                     "' to invalid value ", src_as_str));
+      ABSL_INTERNAL_LOG(ERROR, absl::StrCat("Attempt to set flag '", Name(),
+                                            "' to invalid value ", src_as_str));
     }
     Delete(op_, obj);
   }
@@ -301,15 +308,14 @@ void FlagImpl::Write(const CommandLineFlag& flag, const void* src,
 //  * Update the flag's default value
 //  * Update the current flag value if it was never set before
 // The mode is selected based on 'set_mode' parameter.
-bool FlagImpl::SetFromString(const CommandLineFlag& flag,
-                             absl::string_view value, FlagSettingMode set_mode,
+bool FlagImpl::SetFromString(absl::string_view value, FlagSettingMode set_mode,
                              ValueSource source, std::string* err) {
   absl::MutexLock l(DataGuard());
 
   switch (set_mode) {
     case SET_FLAGS_VALUE: {
       // set or modify the flag's value
-      if (!TryParse(flag, &cur_, value, err)) return false;
+      if (!TryParse(&cur_, value, err)) return false;
       modified_ = true;
       counter_++;
       StoreAtomic();
@@ -323,7 +329,7 @@ bool FlagImpl::SetFromString(const CommandLineFlag& flag,
     case SET_FLAG_IF_DEFAULT: {
       // set the flag's value, but only if it hasn't been set by someone else
       if (!modified_) {
-        if (!TryParse(flag, &cur_, value, err)) return false;
+        if (!TryParse(&cur_, value, err)) return false;
         modified_ = true;
         counter_++;
         StoreAtomic();
@@ -341,12 +347,12 @@ bool FlagImpl::SetFromString(const CommandLineFlag& flag,
     }
     case SET_FLAGS_DEFAULT: {
       if (def_kind_ == FlagDefaultSrcKind::kDynamicValue) {
-        if (!TryParse(flag, &default_src_.dynamic_value, value, err)) {
+        if (!TryParse(&default_src_.dynamic_value, value, err)) {
           return false;
         }
       } else {
         void* new_default_val = nullptr;
-        if (!TryParse(flag, &new_default_val, value, err)) {
+        if (!TryParse(&new_default_val, value, err)) {
           return false;
         }
 
@@ -367,8 +373,7 @@ bool FlagImpl::SetFromString(const CommandLineFlag& flag,
   return true;
 }
 
-void FlagImpl::CheckDefaultValueParsingRoundtrip(
-    const CommandLineFlag& flag) const {
+void FlagImpl::CheckDefaultValueParsingRoundtrip() const {
   std::string v = DefaultValue();
 
   absl::MutexLock lock(DataGuard());
@@ -378,7 +383,7 @@ void FlagImpl::CheckDefaultValueParsingRoundtrip(
   if (!flags_internal::Parse(marshalling_op_, v, dst.get(), &error)) {
     ABSL_INTERNAL_LOG(
         FATAL,
-        absl::StrCat("Flag ", flag.Name(), " (from ", flag.Filename(),
+        absl::StrCat("Flag ", Name(), " (from ", Filename(),
                      "): std::string form of default value '", v,
                      "' could not be parsed; error=", error));
   }
diff --git a/absl/flags/internal/flag.h b/absl/flags/internal/flag.h
index 21a10c7f85f8..7d5271c40de6 100644
--- a/absl/flags/internal/flag.h
+++ b/absl/flags/internal/flag.h
@@ -82,6 +82,8 @@ struct HelpInitArg {
   FlagHelpSrcKind kind;
 };
 
+extern const char kStrippedFlagHelp[];
+
 // HelpConstexprWrap is used by struct AbslFlagHelpGenFor##name generated by
 // ABSL_FLAG macro. It is only used to silence the compiler in the case where
 // help message expression is not constexpr and does not have type const char*.
@@ -148,11 +150,14 @@ struct DynValueDeleter {
 // The class encapsulates the Flag's data and safe access to it.
 class FlagImpl {
  public:
-  constexpr FlagImpl(const flags_internal::FlagOpFn op,
+  constexpr FlagImpl(const char* name, const char* filename,
+                     const flags_internal::FlagOpFn op,
                      const flags_internal::FlagMarshallingOpFn marshalling_op,
-                     const flags_internal::FlagDfltGenFunc default_value_gen,
-                     const HelpInitArg help)
-      : op_(op),
+                     const HelpInitArg help,
+                     const flags_internal::FlagDfltGenFunc default_value_gen)
+      : name_(name),
+        filename_(filename),
+        op_(op),
         marshalling_op_(marshalling_op),
         help_(help.source),
         help_source_kind_(help.kind),
@@ -164,18 +169,18 @@ class FlagImpl {
   void Destroy();
 
   // Constant access methods
+  absl::string_view Name() const;
+  std::string Filename() const;
   std::string Help() const;
   bool IsModified() const ABSL_LOCKS_EXCLUDED(*DataGuard());
   bool IsSpecifiedOnCommandLine() const ABSL_LOCKS_EXCLUDED(*DataGuard());
   std::string DefaultValue() const ABSL_LOCKS_EXCLUDED(*DataGuard());
   std::string CurrentValue() const ABSL_LOCKS_EXCLUDED(*DataGuard());
-  void Read(const CommandLineFlag& flag, void* dst,
-            const flags_internal::FlagOpFn dst_op) const
+  void Read(void* dst, const flags_internal::FlagOpFn dst_op) const
       ABSL_LOCKS_EXCLUDED(*DataGuard());
   // Attempts to parse supplied `value` std::string. If parsing is successful, then
   // it replaces `dst` with the new value.
-  bool TryParse(const CommandLineFlag& flag, void** dst,
-                absl::string_view value, std::string* err) const
+  bool TryParse(void** dst, absl::string_view value, std::string* err) const
       ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard());
   template <typename T>
   bool AtomicGet(T* v) const {
@@ -189,12 +194,11 @@ class FlagImpl {
   }
 
   // Mutating access methods
-  void Write(const CommandLineFlag& flag, const void* src,
-             const flags_internal::FlagOpFn src_op)
+  void Write(const void* src, const flags_internal::FlagOpFn src_op)
+      ABSL_LOCKS_EXCLUDED(*DataGuard());
+  bool SetFromString(absl::string_view value, FlagSettingMode set_mode,
+                     ValueSource source, std::string* err)
       ABSL_LOCKS_EXCLUDED(*DataGuard());
-  bool SetFromString(const CommandLineFlag& flag, absl::string_view value,
-                     FlagSettingMode set_mode, ValueSource source,
-                     std::string* err) ABSL_LOCKS_EXCLUDED(*DataGuard());
   // If possible, updates copy of the Flag's value that is stored in an
   // atomic word.
   void StoreAtomic() ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard());
@@ -214,12 +218,11 @@ class FlagImpl {
     return absl::make_unique<flags_internal::FlagState<T>>(
         flag, std::move(cur_value), modified_, on_command_line_, counter_);
   }
-  bool RestoreState(const CommandLineFlag& flag, const void* value,
-                    bool modified, bool on_command_line, int64_t counter)
-      ABSL_LOCKS_EXCLUDED(*DataGuard());
+  bool RestoreState(const void* value, bool modified, bool on_command_line,
+                    int64_t counter) ABSL_LOCKS_EXCLUDED(*DataGuard());
 
   // Value validation interfaces.
-  void CheckDefaultValueParsingRoundtrip(const CommandLineFlag& flag) const
+  void CheckDefaultValueParsingRoundtrip() const
       ABSL_LOCKS_EXCLUDED(*DataGuard());
   bool ValidateInputValue(absl::string_view value) const
       ABSL_LOCKS_EXCLUDED(*DataGuard());
@@ -235,7 +238,10 @@ class FlagImpl {
       ABSL_EXCLUSIVE_LOCKS_REQUIRED(*DataGuard());
 
   // Immutable Flag's data.
-  const FlagOpFn op_;                         // Type-specific handler.
+  // Constant configuration for a particular flag.
+  const char* const name_;      // Flags name passed to ABSL_FLAG as second arg.
+  const char* const filename_;  // The file name where ABSL_FLAG resides.
+  const FlagOpFn op_;           // Type-specific handler.
   const FlagMarshallingOpFn marshalling_op_;  // Marshalling ops handler.
   const FlagHelpSrc help_;  // Help message literal or function to generate it.
   // Indicates if help message was supplied as literal or generator func.
@@ -286,13 +292,12 @@ class FlagImpl {
 template <typename T>
 class Flag final : public flags_internal::CommandLineFlag {
  public:
-  constexpr Flag(const char* name, const flags_internal::HelpInitArg help,
-                 const char* filename,
+  constexpr Flag(const char* name, const char* filename,
                  const flags_internal::FlagMarshallingOpFn marshalling_op,
-                 const flags_internal::FlagDfltGenFunc initial_value_gen)
-      : flags_internal::CommandLineFlag(name, filename),
-        impl_(&flags_internal::FlagOps<T>, marshalling_op, initial_value_gen,
-              help) {}
+                 const flags_internal::HelpInitArg help,
+                 const flags_internal::FlagDfltGenFunc default_value_gen)
+      : impl_(name, filename, &flags_internal::FlagOps<T>, marshalling_op, help,
+              default_value_gen) {}
 
   T Get() const {
     // See implementation notes in CommandLineFlag::Get().
@@ -303,19 +308,22 @@ class Flag final : public flags_internal::CommandLineFlag {
     };
     U u;
 
-    impl_.Read(*this, &u.value, &flags_internal::FlagOps<T>);
+    impl_.Read(&u.value, &flags_internal::FlagOps<T>);
     return std::move(u.value);
   }
 
   bool AtomicGet(T* v) const { return impl_.AtomicGet(v); }
 
-  void Set(const T& v) { impl_.Write(*this, &v, &flags_internal::FlagOps<T>); }
+  void Set(const T& v) { impl_.Write(&v, &flags_internal::FlagOps<T>); }
 
   void SetCallback(const flags_internal::FlagCallback mutation_callback) {
     impl_.SetCallback(mutation_callback);
   }
 
   // CommandLineFlag interface
+  absl::string_view Name() const override { return impl_.Name(); }
+  std::string Filename() const override { return impl_.Filename(); }
+  absl::string_view Typename() const override { return ""; }
   std::string Help() const override { return impl_.Help(); }
   bool IsModified() const override { return impl_.IsModified(); }
   bool IsSpecifiedOnCommandLine() const override {
@@ -338,20 +346,19 @@ class Flag final : public flags_internal::CommandLineFlag {
   // Restores the flag state to the supplied state object. If there is
   // nothing to restore returns false. Otherwise returns true.
   bool RestoreState(const flags_internal::FlagState<T>& flag_state) {
-    return impl_.RestoreState(*this, &flag_state.cur_value_,
-                              flag_state.modified_, flag_state.on_command_line_,
-                              flag_state.counter_);
+    return impl_.RestoreState(&flag_state.cur_value_, flag_state.modified_,
+                              flag_state.on_command_line_, flag_state.counter_);
   }
 
   bool SetFromString(absl::string_view value,
                      flags_internal::FlagSettingMode set_mode,
                      flags_internal::ValueSource source,
                      std::string* error) override {
-    return impl_.SetFromString(*this, value, set_mode, source, error);
+    return impl_.SetFromString(value, set_mode, source, error);
   }
 
   void CheckDefaultValueParsingRoundtrip() const override {
-    impl_.CheckDefaultValueParsingRoundtrip(*this);
+    impl_.CheckDefaultValueParsingRoundtrip();
   }
 
  private:
@@ -360,7 +367,7 @@ class Flag final : public flags_internal::CommandLineFlag {
   void Destroy() override { impl_.Destroy(); }
 
   void Read(void* dst) const override {
-    impl_.Read(*this, dst, &flags_internal::FlagOps<T>);
+    impl_.Read(dst, &flags_internal::FlagOps<T>);
   }
   flags_internal::FlagOpFn TypeId() const override {
     return &flags_internal::FlagOps<T>;
@@ -416,20 +423,6 @@ T* MakeFromDefaultValue(EmptyBraces) {
   return new T;
 }
 
-// MakeFromDefaultValueOrEmpty is basically the same as MakeFromDefaultValue. It
-// also allows for empty macro parameter (hence no argument), which was somehow
-// widely used for ABSL_RETIRED_FLAG().
-
-template <typename T>
-T* MakeFromDefaultValueOrEmpty(T t) {
-  return MakeFromDefaultValue(std::move(t));
-}
-
-template <typename T>
-T* MakeFromDefaultValueOrEmpty() {
-  return MakeFromDefaultValue<T>(EmptyBraces());
-}
-
 }  // namespace flags_internal
 ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/flags/internal/registry.cc b/absl/flags/internal/registry.cc
index 5eae933c3fa3..ae5afd42ee36 100644
--- a/absl/flags/internal/registry.cc
+++ b/absl/flags/internal/registry.cc
@@ -277,9 +277,7 @@ namespace {
 class RetiredFlagObj final : public flags_internal::CommandLineFlag {
  public:
   constexpr RetiredFlagObj(const char* name, FlagOpFn ops)
-      : flags_internal::CommandLineFlag(name,
-                                        /*filename=*/"RETIRED"),
-        op_(ops) {}
+      : name_(name), op_(ops) {}
 
  private:
   void Destroy() override {
@@ -287,6 +285,9 @@ class RetiredFlagObj final : public flags_internal::CommandLineFlag {
     delete this;
   }
 
+  absl::string_view Name() const override { return name_; }
+  std::string Filename() const override { return "RETIRED"; }
+  absl::string_view Typename() const override { return ""; }
   flags_internal::FlagOpFn TypeId() const override { return op_; }
   std::string Help() const override { return ""; }
   bool IsRetired() const override { return true; }
@@ -312,6 +313,7 @@ class RetiredFlagObj final : public flags_internal::CommandLineFlag {
   void Read(void*) const override {}
 
   // Data members
+  const char* const name_;
   const FlagOpFn op_;
 };