Export of internal Abseil changes

--
97faa5fdfa4cd5d7a74cd9332cddd8a7c1e67b89 by Abseil Team <absl-team@google.com>:

Internal changes

PiperOrigin-RevId: 295164378

--
74990f100b3f4172c770ef8c76c05c8e99febdde by Xiaoyi Zhang <zhangxy@google.com>:

Release `absl::Cord`.

PiperOrigin-RevId: 295161959

--
6018c57f43c45c31dc1a61c0cd75fa2aa9be8dab by Gennadiy Rozental <rogeeff@google.com>:

Introduce independent notion of FlagStaticTypeID.

This change separates static flag value type identification from the type specific "vtable" with all the operations specific to value type. This change allows us to do the following:
* We can move most of "vtable" implementation from handle header, which will become public soon, into implementation details of Abseil Flag.
* We can combine back marshalling ops and general ops into a single vtable routine. They were split previously to facilitate type identification without requiring marshalling routines to be exposed in header.
* We do not need to store two vtable pointers. We can now store only one. The static type id can be deduced on request.

Overall we are saving 24 bytes per flag according to size_tester run.

PiperOrigin-RevId: 295149687

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986b78e9ba571aa85154e70bda4580edd45bb7bf by Abseil Team <absl-team@google.com>:

Update internal comments.

PiperOrigin-RevId: 295030681

--
825412b29fd6015027bbc3e5f802706eee0d2837 by Matthew Brown <matthewbr@google.com>:

Change str_format_internal::ConversionChar to an enum (from a struct-wrapped enum).

PiperOrigin-RevId: 294987462

--
f9f88d91809d2cc33fc129df70fa93e7a2c35c69 by Derek Mauro <dmauro@google.com>:

Use more precise wording in the question on live-at-head

PiperOrigin-RevId: 294957679
GitOrigin-RevId: 97faa5fdfa4cd5d7a74cd9332cddd8a7c1e67b89
Change-Id: I081e70d148ffac7296d65e2a2f775f643eaf70bf

7 files changed, 165 insertions, 176 deletions

diff --git a/absl/flags/flag.h b/absl/flags/flag.h
index 274838cbc7f0..cff02c1fcb61 100644
--- a/absl/flags/flag.h
+++ b/absl/flags/flag.h
@@ -100,12 +100,10 @@ class Flag {
   // constexpr initializable.
 #if _MSC_VER <= 1900
   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),
         filename_(filename),
-        marshalling_op_(marshalling_op),
         help_gen_(help_gen),
         default_value_gen_(default_value_gen),
         inited_(false),
@@ -121,7 +119,7 @@ class Flag {
       }
 
       impl_ =
-          new flags_internal::Flag<T>(name_, filename_, marshalling_op_,
+          new flags_internal::Flag<T>(name_, filename_,
                                       {flags_internal::FlagHelpMsg(help_gen_),
                                        flags_internal::FlagHelpKind::kGenFunc},
                                       default_value_gen_);
@@ -161,7 +159,6 @@ class Flag {
   // this to be an aggregate type.
   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_;
 
@@ -335,7 +332,6 @@ ABSL_NAMESPACE_END
   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>,              \
       absl::flags_internal::HelpArg<AbslFlagHelpGenFor##name>(0),   \
       &AbslFlagsInitFlag##name};                                    \
   extern bool FLAGS_no##name;                                       \
@@ -349,7 +345,6 @@ ABSL_NAMESPACE_END
   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)
diff --git a/absl/flags/flag_test.cc b/absl/flags/flag_test.cc
index 6429a3e1e1b3..4984d28403b2 100644
--- a/absl/flags/flag_test.cc
+++ b/absl/flags/flag_test.cc
@@ -53,14 +53,13 @@ template <typename T>
 bool TestConstructionFor() {
   constexpr flags::FlagHelpArg help_arg{flags::FlagHelpMsg("literal help"),
                                         flags::FlagHelpKind::kLiteral};
-  constexpr flags::Flag<T> f1("f1", "file", &flags::FlagMarshallingOps<T>,
-                              help_arg, &TestMakeDflt<T>);
+  constexpr flags::Flag<T> f1("f1", "file", 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", "file", &flags::FlagMarshallingOps<T>,
+      "f2", "file",
       {flags::FlagHelpMsg(&TestHelpMsg), flags::FlagHelpKind::kGenFunc},
       &TestMakeDflt<T>);
   flags::FlagRegistrar<T, false>(&f2).OnUpdate(TestCallback);
diff --git a/absl/flags/internal/commandlineflag.h b/absl/flags/internal/commandlineflag.h
index 4ac50190c6c0..6363c6615b12 100644
--- a/absl/flags/internal/commandlineflag.h
+++ b/absl/flags/internal/commandlineflag.h
@@ -34,22 +34,23 @@ namespace absl {
 ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 
-// Type-specific operations, eg., parsing, copying, etc. are provided
-// by function specific to that type with a signature matching FlagOpFn.
-enum FlagOp {
-  kDelete,
-  kClone,
-  kCopy,
-  kCopyConstruct,
-  kSizeof,
-  kParse,
-  kUnparse,
+// An alias for flag static type id. Values of type identify the flag value type
+// simialarly to typeid(T), but without relying on RTTI being available. In most
+// cases this id is enough to uniquely identify the flag's value type. In a few
+// cases we'll have to resort to using actual RTTI implementation if it is
+// available.
+using FlagStaticTypeId = void* (*)();
+
+// Address of this function template is used in current implementation as a flag
+// static type id.
+template <typename T>
+void* FlagStaticTypeIdGen() {
 #if defined(ABSL_FLAGS_INTERNAL_HAS_RTTI)
-  kRuntimeTypeId
+  return const_cast<std::type_info*>(&typeid(T));
+#else
+  return nullptr;
 #endif
-};
-using FlagOpFn = void* (*)(FlagOp, const void*, void*);
-using FlagMarshallingOpFn = void* (*)(FlagOp, const void*, void*, void*);
+}
 
 // Options that control SetCommandLineOptionWithMode.
 enum FlagSettingMode {
@@ -72,97 +73,6 @@ enum ValueSource {
   kProgrammaticChange,
 };
 
-// The per-type function
-template <typename T>
-void* FlagOps(FlagOp op, const void* v1, void* v2) {
-  switch (op) {
-    case kDelete:
-      delete static_cast<const T*>(v1);
-      return nullptr;
-    case kClone:
-      return new T(*static_cast<const T*>(v1));
-    case kCopy:
-      *static_cast<T*>(v2) = *static_cast<const T*>(v1);
-      return nullptr;
-    case kCopyConstruct:
-      new (v2) T(*static_cast<const T*>(v1));
-      return nullptr;
-    case kSizeof:
-      return reinterpret_cast<void*>(sizeof(T));
-#if defined(ABSL_FLAGS_INTERNAL_HAS_RTTI)
-    case kRuntimeTypeId:
-      return const_cast<std::type_info*>(&typeid(T));
-      break;
-#endif
-    default:
-      return nullptr;
-  }
-}
-
-template <typename T>
-void* FlagMarshallingOps(FlagOp op, const void* v1, void* v2, void* v3) {
-  switch (op) {
-    case kParse: {
-      // initialize the temporary instance of type T based on current value in
-      // destination (which is going to be flag's default value).
-      T temp(*static_cast<T*>(v2));
-      if (!absl::ParseFlag<T>(*static_cast<const absl::string_view*>(v1), &temp,
-                              static_cast<std::string*>(v3))) {
-        return nullptr;
-      }
-      *static_cast<T*>(v2) = std::move(temp);
-      return v2;
-    }
-    case kUnparse:
-      *static_cast<std::string*>(v2) =
-          absl::UnparseFlag<T>(*static_cast<const T*>(v1));
-      return nullptr;
-    default:
-      return nullptr;
-  }
-}
-
-// Functions that invoke flag-type-specific operations.
-inline void Delete(FlagOpFn op, const void* obj) {
-  op(flags_internal::kDelete, obj, nullptr);
-}
-
-inline void* Clone(FlagOpFn op, const void* obj) {
-  return op(flags_internal::kClone, obj, nullptr);
-}
-
-inline void Copy(FlagOpFn op, const void* src, void* dst) {
-  op(flags_internal::kCopy, src, dst);
-}
-
-inline void CopyConstruct(FlagOpFn op, const void* src, void* dst) {
-  op(flags_internal::kCopyConstruct, src, dst);
-}
-
-inline bool Parse(FlagMarshallingOpFn op, absl::string_view text, void* dst,
-                  std::string* error) {
-  return op(flags_internal::kParse, &text, dst, error) != nullptr;
-}
-
-inline std::string Unparse(FlagMarshallingOpFn op, const void* val) {
-  std::string result;
-  op(flags_internal::kUnparse, val, &result, nullptr);
-  return result;
-}
-
-inline size_t Sizeof(FlagOpFn op) {
-  // This sequence of casts reverses the sequence from base::internal::FlagOps()
-  return static_cast<size_t>(reinterpret_cast<intptr_t>(
-      op(flags_internal::kSizeof, nullptr, nullptr)));
-}
-
-#if defined(ABSL_FLAGS_INTERNAL_HAS_RTTI)
-inline const std::type_info& RuntimeTypeId(FlagOpFn op) {
-  return *static_cast<const std::type_info*>(
-      op(flags_internal::kRuntimeTypeId, nullptr, nullptr));
-}
-#endif
-
 // Handle to FlagState objects. Specific flag state objects will restore state
 // of a flag produced this flag state from method CommandLineFlag::SaveState().
 class FlagStateInterface {
@@ -187,7 +97,7 @@ class CommandLineFlag {
   // Return true iff flag has type T.
   template <typename T>
   inline bool IsOfType() const {
-    return TypeId() == &flags_internal::FlagOps<T>;
+    return TypeId() == &flags_internal::FlagStaticTypeIdGen<T>;
   }
 
   // Attempts to retrieve the flag value. Returns value on success,
@@ -240,7 +150,7 @@ class CommandLineFlag {
   // Returns true iff this is a handle to an Abseil Flag.
   virtual bool IsAbseilFlag() const { return true; }
   // Returns id of the flag's value type.
-  virtual flags_internal::FlagOpFn TypeId() const = 0;
+  virtual FlagStaticTypeId TypeId() const = 0;
   virtual bool IsModified() const = 0;
   virtual bool IsSpecifiedOnCommandLine() const = 0;
   virtual std::string DefaultValue() const = 0;
diff --git a/absl/flags/internal/flag.cc b/absl/flags/internal/flag.cc
index 721e411e0875..83ec8df19149 100644
--- a/absl/flags/internal/flag.cc
+++ b/absl/flags/internal/flag.cc
@@ -47,23 +47,15 @@ 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(FlagOpFn flag_type_id) {
+bool ShouldValidateFlagValue(FlagStaticTypeId flag_type_id) {
 #define DONT_VALIDATE(T) \
-  if (flag_type_id == &flags_internal::FlagOps<T>) return false;
+  if (flag_type_id == &FlagStaticTypeIdGen<T>) return false;
   ABSL_FLAGS_INTERNAL_BUILTIN_TYPES(DONT_VALIDATE)
 #undef DONT_VALIDATE
 
   return true;
 }
 
-#if defined(ABSL_FLAGS_INTERNAL_HAS_RTTI)
-bool MatchRuntimeTypeId(FlagOpFn lhs_type_id, FlagOpFn rhs_type_id) {
-  return RuntimeTypeId(lhs_type_id) == RuntimeTypeId(rhs_type_id);
-}
-#else
-bool MatchRuntimeTypeId(FlagOpFn, FlagOpFn) { return true; }
-#endif
-
 // RAII helper used to temporarily unlock and relock `absl::Mutex`.
 // This is used when we need to ensure that locks are released while
 // invoking user supplied callbacks and then reacquired, since callbacks may
@@ -101,22 +93,35 @@ absl::Mutex* FlagImpl::DataGuard() const {
   return reinterpret_cast<absl::Mutex*>(&data_guard_);
 }
 
-void FlagImpl::AssertValidType(const flags_internal::FlagOpFn op) const {
-  // `op` is the unmarshaling operation corresponding to the declaration
-  // visibile at the call site. `op_` is the Flag's defined unmarshalling
-  // operation. They must match for this operation to be well-defined.
-  if (ABSL_PREDICT_FALSE(op != op_) && !MatchRuntimeTypeId(op, op_)) {
-    ABSL_INTERNAL_LOG(
-        FATAL,
-        absl::StrCat("Flag '", Name(),
-                     "' is defined as one type and declared as another"));
-  }
+void FlagImpl::AssertValidType(FlagStaticTypeId type_id) const {
+  FlagStaticTypeId this_type_id = flags_internal::StaticTypeId(op_);
+
+  // `type_id` is the type id corresponding to the declaration visibile at the
+  // call site. `this_type_id` is the type id corresponding to the type stored
+  // during flag definition. They must match for this operation to be
+  // well-defined.
+  if (ABSL_PREDICT_TRUE(type_id == this_type_id)) return;
+
+  void* lhs_runtime_type_id = type_id();
+  void* rhs_runtime_type_id = this_type_id();
+
+  if (lhs_runtime_type_id == rhs_runtime_type_id) return;
+
+#if defined(ABSL_FLAGS_INTERNAL_HAS_RTTI)
+  if (*reinterpret_cast<std::type_info*>(lhs_runtime_type_id) ==
+      *reinterpret_cast<std::type_info*>(rhs_runtime_type_id))
+    return;
+#endif
+
+  ABSL_INTERNAL_LOG(
+      FATAL, absl::StrCat("Flag '", Name(),
+                          "' is defined as one type and declared as another"));
 }
 
 std::unique_ptr<void, DynValueDeleter> FlagImpl::MakeInitValue() const {
   void* res = nullptr;
   if (DefaultKind() == FlagDefaultKind::kDynamicValue) {
-    res = Clone(op_, default_src_.dynamic_value);
+    res = flags_internal::Clone(op_, default_src_.dynamic_value);
   } else {
     res = (*default_src_.gen_func)();
   }
@@ -148,13 +153,13 @@ std::string FlagImpl::DefaultValue() const {
   absl::MutexLock l(DataGuard());
 
   auto obj = MakeInitValue();
-  return Unparse(marshalling_op_, obj.get());
+  return flags_internal::Unparse(op_, obj.get());
 }
 
 std::string FlagImpl::CurrentValue() const {
   absl::MutexLock l(DataGuard());
 
-  return Unparse(marshalling_op_, value_.dynamic);
+  return flags_internal::Unparse(op_, value_.dynamic);
 }
 
 void FlagImpl::SetCallback(const FlagCallbackFunc mutation_callback) {
@@ -220,7 +225,7 @@ bool FlagImpl::TryParse(void** dst, absl::string_view value,
   auto tentative_value = MakeInitValue();
 
   std::string parse_err;
-  if (!Parse(marshalling_op_, value, tentative_value.get(), &parse_err)) {
+  if (!flags_internal::Parse(op_, value, tentative_value.get(), &parse_err)) {
     absl::string_view err_sep = parse_err.empty() ? "" : "; ";
     *err = absl::StrCat("Illegal value '", value, "' specified for flag '",
                         Name(), "'", err_sep, parse_err);
@@ -237,11 +242,11 @@ bool FlagImpl::TryParse(void** dst, absl::string_view value,
 void FlagImpl::Read(void* dst) const {
   absl::ReaderMutexLock l(DataGuard());
 
-  CopyConstruct(op_, value_.dynamic, dst);
+  flags_internal::CopyConstruct(op_, value_.dynamic, dst);
 }
 
 void FlagImpl::StoreAtomic() {
-  size_t data_size = Sizeof(op_);
+  size_t data_size = flags_internal::Sizeof(op_);
 
   if (data_size <= sizeof(int64_t)) {
     int64_t t = 0;
@@ -260,20 +265,20 @@ void FlagImpl::StoreAtomic() {
 void FlagImpl::Write(const void* src) {
   absl::MutexLock l(DataGuard());
 
-  if (ShouldValidateFlagValue(op_)) {
-    void* obj = Clone(op_, src);
+  if (ShouldValidateFlagValue(flags_internal::StaticTypeId(op_))) {
+    void* obj = flags_internal::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)) {
+    std::string src_as_str = flags_internal::Unparse(op_, src);
+    if (!flags_internal::Parse(op_, src_as_str, obj, &ignored_error)) {
       ABSL_INTERNAL_LOG(ERROR, absl::StrCat("Attempt to set flag '", Name(),
                                             "' to invalid value ", src_as_str));
     }
-    Delete(op_, obj);
+    flags_internal::Delete(op_, obj);
   }
 
   modified_ = true;
   counter_++;
-  Copy(op_, src, value_.dynamic);
+  flags_internal::Copy(op_, src, value_.dynamic);
 
   StoreAtomic();
   InvokeCallback();
@@ -341,7 +346,7 @@ bool FlagImpl::SetFromString(absl::string_view value, FlagSettingMode set_mode,
 
       if (!modified_) {
         // Need to set both default value *and* current, in this case
-        Copy(op_, default_src_.dynamic_value, value_.dynamic);
+        flags_internal::Copy(op_, default_src_.dynamic_value, value_.dynamic);
         StoreAtomic();
         InvokeCallback();
       }
@@ -359,7 +364,7 @@ void FlagImpl::CheckDefaultValueParsingRoundtrip() const {
 
   auto dst = MakeInitValue();
   std::string error;
-  if (!flags_internal::Parse(marshalling_op_, v, dst.get(), &error)) {
+  if (!flags_internal::Parse(op_, v, dst.get(), &error)) {
     ABSL_INTERNAL_LOG(
         FATAL,
         absl::StrCat("Flag ", Name(), " (from ", Filename(),
@@ -376,8 +381,7 @@ bool FlagImpl::ValidateInputValue(absl::string_view value) const {
 
   auto obj = MakeInitValue();
   std::string ignored_error;
-  return flags_internal::Parse(marshalling_op_, value, obj.get(),
-                               &ignored_error);
+  return flags_internal::Parse(op_, value, obj.get(), &ignored_error);
 }
 
 }  // namespace flags_internal
diff --git a/absl/flags/internal/flag.h b/absl/flags/internal/flag.h
index b426ccb571a6..1c2f15dd7388 100644
--- a/absl/flags/internal/flag.h
+++ b/absl/flags/internal/flag.h
@@ -43,6 +43,94 @@ template <typename T>
 class Flag;
 
 ///////////////////////////////////////////////////////////////////////////////
+// Type-specific operations, eg., parsing, copying, etc. are provided
+// by function specific to that type with a signature matching FlagOpFn.
+
+enum FlagOp {
+  kDelete,
+  kClone,
+  kCopy,
+  kCopyConstruct,
+  kSizeof,
+  kStaticTypeId,
+  kParse,
+  kUnparse,
+};
+using FlagOpFn = void* (*)(FlagOp, const void*, void*, void*);
+
+// The per-type function
+template <typename T>
+void* FlagOps(FlagOp op, const void* v1, void* v2, void* v3) {
+  switch (op) {
+    case flags_internal::kDelete:
+      delete static_cast<const T*>(v1);
+      return nullptr;
+    case flags_internal::kClone:
+      return new T(*static_cast<const T*>(v1));
+    case flags_internal::kCopy:
+      *static_cast<T*>(v2) = *static_cast<const T*>(v1);
+      return nullptr;
+    case flags_internal::kCopyConstruct:
+      new (v2) T(*static_cast<const T*>(v1));
+      return nullptr;
+    case flags_internal::kSizeof:
+      return reinterpret_cast<void*>(sizeof(T));
+    case flags_internal::kStaticTypeId:
+      return reinterpret_cast<void*>(&FlagStaticTypeIdGen<T>);
+    case flags_internal::kParse: {
+      // Initialize the temporary instance of type T based on current value in
+      // destination (which is going to be flag's default value).
+      T temp(*static_cast<T*>(v2));
+      if (!absl::ParseFlag<T>(*static_cast<const absl::string_view*>(v1), &temp,
+                              static_cast<std::string*>(v3))) {
+        return nullptr;
+      }
+      *static_cast<T*>(v2) = std::move(temp);
+      return v2;
+    }
+    case flags_internal::kUnparse:
+      *static_cast<std::string*>(v2) =
+          absl::UnparseFlag<T>(*static_cast<const T*>(v1));
+      return nullptr;
+    default:
+      return nullptr;
+  }
+}
+
+// Functions that invoke flag-type-specific operations.
+inline void Delete(FlagOpFn op, const void* obj) {
+  op(flags_internal::kDelete, obj, nullptr, nullptr);
+}
+inline void* Clone(FlagOpFn op, const void* obj) {
+  return op(flags_internal::kClone, obj, nullptr, nullptr);
+}
+inline void Copy(FlagOpFn op, const void* src, void* dst) {
+  op(flags_internal::kCopy, src, dst, nullptr);
+}
+inline void CopyConstruct(FlagOpFn op, const void* src, void* dst) {
+  op(flags_internal::kCopyConstruct, src, dst, nullptr);
+}
+inline bool Parse(FlagOpFn op, absl::string_view text, void* dst,
+                  std::string* error) {
+  return op(flags_internal::kParse, &text, dst, error) != nullptr;
+}
+inline std::string Unparse(FlagOpFn op, const void* val) {
+  std::string result;
+  op(flags_internal::kUnparse, val, &result, nullptr);
+  return result;
+}
+inline size_t Sizeof(FlagOpFn op) {
+  // This sequence of casts reverses the sequence from
+  // `flags_internal::FlagOps()`
+  return static_cast<size_t>(reinterpret_cast<intptr_t>(
+      op(flags_internal::kSizeof, nullptr, nullptr, nullptr)));
+}
+inline FlagStaticTypeId StaticTypeId(FlagOpFn op) {
+  return reinterpret_cast<FlagStaticTypeId>(
+      op(flags_internal::kStaticTypeId, nullptr, nullptr, nullptr));
+}
+
+///////////////////////////////////////////////////////////////////////////////
 // Persistent state of the flag data.
 
 template <typename T>
@@ -273,12 +361,10 @@ struct DynValueDeleter {
 class FlagImpl {
  public:
   constexpr FlagImpl(const char* name, const char* filename, FlagOpFn op,
-                     FlagMarshallingOpFn marshalling_op, FlagHelpArg help,
-                     FlagDfltGenFunc default_value_gen)
+                     FlagHelpArg help, FlagDfltGenFunc default_value_gen)
       : name_(name),
         filename_(filename),
         op_(op),
-        marshalling_op_(marshalling_op),
         help_(help.source),
         help_source_kind_(static_cast<uint8_t>(help.kind)),
         def_kind_(static_cast<uint8_t>(FlagDefaultKind::kGenFunc)),
@@ -306,7 +392,7 @@ class FlagImpl {
   template <typename T, typename std::enable_if<
                             !IsAtomicFlagTypeTrait<T>::value, int>::type = 0>
   void Get(T* dst) const {
-    AssertValidType(&flags_internal::FlagOps<T>);
+    AssertValidType(&flags_internal::FlagStaticTypeIdGen<T>);
     Read(dst);
   }
   // Overload for `GetFlag()` for types that support lock-free reads.
@@ -317,7 +403,7 @@ class FlagImpl {
     // slowing down flag value access due to type validation. That's why
     // this validation is hidden behind !NDEBUG
 #ifndef NDEBUG
-    AssertValidType(&flags_internal::FlagOps<T>);
+    AssertValidType(&flags_internal::FlagStaticTypeIdGen<T>);
 #endif
     using U = flags_internal::BestAtomicType<T>;
     typename U::type r = value_.atomics.template load<T>();
@@ -329,7 +415,7 @@ class FlagImpl {
   }
   template <typename T>
   void Set(const T& src) {
-    AssertValidType(&flags_internal::FlagOps<T>);
+    AssertValidType(&flags_internal::FlagStaticTypeIdGen<T>);
     Write(&src);
   }
 
@@ -388,7 +474,7 @@ class FlagImpl {
   // int. To do that we pass the "assumed" type id (which is deduced from type
   // int) as an argument `op`, which is in turn is validated against the type id
   // stored in flag object by flag definition statement.
-  void AssertValidType(const flags_internal::FlagOpFn op) const;
+  void AssertValidType(FlagStaticTypeId type_id) const;
 
   // Immutable flag's state.
 
@@ -396,10 +482,8 @@ class FlagImpl {
   const char* const name_;
   // The file name where ABSL_FLAG resides.
   const char* const filename_;
-  // Type-specific handler.
+  // Type-specific operations "vtable".
   const FlagOpFn op_;
-  // Marshalling ops handler.
-  const FlagMarshallingOpFn marshalling_op_;
   // Help message literal or function to generate it.
   const FlagHelpMsg help_;
   // Indicates if help message was supplied as literal or generator func.
@@ -456,12 +540,9 @@ class FlagImpl {
 template <typename T>
 class Flag final : public flags_internal::CommandLineFlag {
  public:
-  constexpr Flag(const char* name, const char* filename,
-                 const FlagMarshallingOpFn marshalling_op,
-                 const FlagHelpArg help,
+  constexpr Flag(const char* name, const char* filename, const FlagHelpArg help,
                  const FlagDfltGenFunc default_value_gen)
-      : impl_(name, filename, &FlagOps<T>, marshalling_op, help,
-              default_value_gen) {}
+      : impl_(name, filename, &FlagOps<T>, help, default_value_gen) {}
 
   T Get() const {
     // See implementation notes in CommandLineFlag::Get().
@@ -520,7 +601,7 @@ class Flag final : public flags_internal::CommandLineFlag {
   friend class FlagState<T>;
 
   void Read(void* dst) const override { impl_.Read(dst); }
-  FlagOpFn TypeId() const override { return &FlagOps<T>; }
+  FlagStaticTypeId TypeId() const override { return &FlagStaticTypeIdGen<T>; }
 
   // Flag's data
   FlagImpl impl_;
diff --git a/absl/flags/internal/registry.cc b/absl/flags/internal/registry.cc
index 2ef16e84864c..e434a8591224 100644
--- a/absl/flags/internal/registry.cc
+++ b/absl/flags/internal/registry.cc
@@ -284,14 +284,14 @@ namespace {
 
 class RetiredFlagObj final : public flags_internal::CommandLineFlag {
  public:
-  constexpr RetiredFlagObj(const char* name, FlagOpFn ops)
-      : name_(name), op_(ops) {}
+  constexpr RetiredFlagObj(const char* name, FlagStaticTypeId type_id)
+      : name_(name), type_id_(type_id) {}
 
  private:
   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_; }
+  FlagStaticTypeId TypeId() const override { return type_id_; }
   std::string Help() const override { return ""; }
   bool IsRetired() const override { return true; }
   bool IsModified() const override { return false; }
@@ -317,7 +317,7 @@ class RetiredFlagObj final : public flags_internal::CommandLineFlag {
 
   // Data members
   const char* const name_;
-  const FlagOpFn op_;
+  const FlagStaticTypeId type_id_;
 };
 
 void DestroyRetiredFlag(flags_internal::CommandLineFlag* flag) {
@@ -327,8 +327,8 @@ void DestroyRetiredFlag(flags_internal::CommandLineFlag* flag) {
 
 }  // namespace
 
-bool Retire(const char* name, FlagOpFn ops) {
-  auto* flag = new flags_internal::RetiredFlagObj(name, ops);
+bool Retire(const char* name, FlagStaticTypeId type_id) {
+  auto* flag = new flags_internal::RetiredFlagObj(name, type_id);
   FlagRegistry::GlobalRegistry()->RegisterFlag(flag);
   return true;
 }
diff --git a/absl/flags/internal/registry.h b/absl/flags/internal/registry.h
index 99cb685b15d4..69ff889fb100 100644
--- a/absl/flags/internal/registry.h
+++ b/absl/flags/internal/registry.h
@@ -79,12 +79,12 @@ bool RegisterCommandLineFlag(CommandLineFlag*);
 //
 
 // Retire flag with name "name" and type indicated by ops.
-bool Retire(const char* name, FlagOpFn ops);
+bool Retire(const char* name, FlagStaticTypeId type_id);
 
 // Registered a retired flag with name 'flag_name' and type 'T'.
 template <typename T>
 inline bool RetiredFlag(const char* flag_name) {
-  return flags_internal::Retire(flag_name, flags_internal::FlagOps<T>);
+  return flags_internal::Retire(flag_name, &FlagStaticTypeIdGen<T>);
 }
 
 // If the flag is retired, returns true and indicates in |*type_is_bool|