Provide information about types of all flags.

PiperOrigin-RevId: 717986118
Change-Id: Ib962482b66e1eac09165767d4a36a91ad49e8fc8

Author: dvyukov

absl/flags/commandlineflag.cc

@@ -24,6 +24,7 @@
 namespace absl {
 ABSL_NAMESPACE_BEGIN
 
+absl::string_view CommandLineFlag::TypeName() const { return ""; }
 bool CommandLineFlag::IsRetired() const { return false; }
 bool CommandLineFlag::ParseFrom(absl::string_view value, std::string* error) {
   return ParseFrom(value, flags_internal::SET_FLAGS_VALUE,

absl/flags/commandlineflag.h

@@ -200,6 +200,13 @@ class CommandLineFlag {
   // Checks that flags default value can be converted to string and back to the
   // flag's value type.
   virtual void CheckDefaultValueParsingRoundtrip() const = 0;
+
+  // absl::CommandLineFlag::TypeName()
+  //
+  // Returns string representation of the type of this flag
+  // (the way it is spelled in the ABSL_FLAG macro).
+  // The default implementation returns the empty string.
+  virtual absl::string_view TypeName() const;
 };
 #if defined(__GNUC__) && !defined(__clang__)
 #pragma GCC diagnostic pop

absl/flags/flag.h

@@ -204,12 +204,14 @@ ABSL_NAMESPACE_END
 
 #if ABSL_FLAGS_STRIP_NAMES
 #define ABSL_FLAG_IMPL_FLAGNAME(txt) ""
+#define ABSL_FLAG_IMPL_TYPENAME(txt) ""
 #define ABSL_FLAG_IMPL_FILENAME() ""
 #define ABSL_FLAG_IMPL_REGISTRAR(T, flag)                                      \
   absl::flags_internal::FlagRegistrar<T, false>(ABSL_FLAG_IMPL_FLAG_PTR(flag), \
                                                 nullptr)
 #else
 #define ABSL_FLAG_IMPL_FLAGNAME(txt) txt
+#define ABSL_FLAG_IMPL_TYPENAME(txt) txt
 #define ABSL_FLAG_IMPL_FILENAME() __FILE__
 #define ABSL_FLAG_IMPL_REGISTRAR(T, flag)                                     \
   absl::flags_internal::FlagRegistrar<T, true>(ABSL_FLAG_IMPL_FLAG_PTR(flag), \
@@ -261,16 +263,17 @@ ABSL_NAMESPACE_END
 // Note: Name of registrar object is not arbitrary. It is used to "grab"
 // global name for FLAGS_no<flag_name> symbol, thus preventing the possibility
 // of defining two flags with names foo and nofoo.
-#define ABSL_FLAG_IMPL(Type, name, default_value, help)                       \
-  extern ::absl::Flag<Type> FLAGS_##name;                                     \
-  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_FLAG_IMPL_HELP_ARG(name), ABSL_FLAG_IMPL_DEFAULT_ARG(Type, name)}; \
-  extern absl::flags_internal::FlagRegistrarEmpty FLAGS_no##name;             \
-  absl::flags_internal::FlagRegistrarEmpty FLAGS_no##name =                   \
+#define ABSL_FLAG_IMPL(Type, name, default_value, help)               \
+  extern ::absl::Flag<Type> FLAGS_##name;                             \
+  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_TYPENAME(#Type), \
+      ABSL_FLAG_IMPL_FILENAME(), ABSL_FLAG_IMPL_HELP_ARG(name),       \
+      ABSL_FLAG_IMPL_DEFAULT_ARG(Type, name)};                        \
+  extern absl::flags_internal::FlagRegistrarEmpty FLAGS_no##name;     \
+  absl::flags_internal::FlagRegistrarEmpty FLAGS_no##name =           \
       ABSL_FLAG_IMPL_REGISTRAR(Type, FLAGS_##name)
 
 // ABSL_RETIRED_FLAG

absl/flags/flag_test.cc

@@ -149,9 +149,9 @@ using uint128 = absl::uint128;
 #define DEFINE_CONSTRUCTED_FLAG(T, dflt, dflt_kind)                        \
   constexpr flags::FlagDefaultArg f1default##T{                            \
       flags::FlagDefaultSrc{dflt}, flags::FlagDefaultKind::dflt_kind};     \
-  constexpr absl::Flag<T> f1##T{"f1", "file", help_arg, f1default##T};     \
+  constexpr absl::Flag<T> f1##T{"f1", #T, "file", help_arg, f1default##T}; \
   ABSL_CONST_INIT absl::Flag<T> f2##T {                                    \
-    "f2", "file",                                                          \
+    "f2", #T, "file",                                                      \
         {flags::FlagHelpMsg(&TestHelpMsg), flags::FlagHelpKind::kGenFunc}, \
         flags::FlagDefaultArg {                                            \
       flags::FlagDefaultSrc(&TestMakeDflt<T>),                             \

absl/flags/internal/flag.cc

@@ -342,6 +342,8 @@ void FlagImpl::StoreValue(const void* src, ValueSource source) {
 
 absl::string_view FlagImpl::Name() const { return name_; }
 
+absl::string_view FlagImpl::TypeName() const { return type_name_; }
+
 std::string FlagImpl::Filename() const {
   return flags_internal::GetUsageConfig().normalize_filename(filename_);
 }

absl/flags/internal/flag.h

@@ -582,10 +582,12 @@ class FlagState;
 #endif
 class FlagImpl final : public CommandLineFlag {
  public:
-  constexpr FlagImpl(const char* name, const char* filename, FlagOpFn op,
-                     FlagHelpArg help, FlagValueStorageKind value_kind,
+  constexpr FlagImpl(const char* name, const char* type_name,
+                     const char* filename, FlagOpFn op, FlagHelpArg help,
+                     FlagValueStorageKind value_kind,
                      FlagDefaultArg default_arg)
       : name_(name),
+        type_name_(type_name),
         filename_(filename),
         op_(op),
         help_(help.source),
@@ -698,6 +700,7 @@ class FlagImpl final : public CommandLineFlag {
 
   // CommandLineFlag interface implementation
   absl::string_view Name() const override;
+  absl::string_view TypeName() const override;
   std::string Filename() const override;
   std::string Help() const override;
   FlagFastTypeId TypeId() const override;
@@ -731,6 +734,10 @@ class FlagImpl final : public CommandLineFlag {
 
   // Flags name passed to ABSL_FLAG as second arg.
   const char* const name_;
+
+  // Flags type passed to ABSL_FLAG as first arg.
+  const char* const type_name_;
+
   // The file name where ABSL_FLAG resides.
   const char* const filename_;
   // Type-specific operations vtable.
@@ -789,9 +796,9 @@ class FlagImpl final : public CommandLineFlag {
 template <typename T>
 class Flag {
  public:
-  constexpr Flag(const char* name, const char* filename, FlagHelpArg help,
-                 const FlagDefaultArg default_arg)
-      : impl_(name, filename, &FlagOps<T>, help,
+  constexpr Flag(const char* name, const char* type_name, const char* filename,
+                 FlagHelpArg help, const FlagDefaultArg default_arg)
+      : impl_(name, type_name, filename, &FlagOps<T>, help,
               flags_internal::StorageKind<T>(), default_arg),
         value_() {}
 

absl/flags/internal/private_handle_accessor.cc

@@ -59,6 +59,10 @@ bool PrivateHandleAccessor::ParseFrom(CommandLineFlag& flag,
   return flag.ParseFrom(value, set_mode, source, error);
 }
 
+absl::string_view PrivateHandleAccessor::TypeName(const CommandLineFlag& flag) {
+  return flag.TypeName();
+}
+
 }  // namespace flags_internal
 ABSL_NAMESPACE_END
 }  // namespace absl

absl/flags/internal/private_handle_accessor.h

@@ -52,6 +52,9 @@ class PrivateHandleAccessor {
   static bool ParseFrom(CommandLineFlag& flag, absl::string_view value,
                         flags_internal::FlagSettingMode set_mode,
                         flags_internal::ValueSource source, std::string& error);
+
+  // Access to CommandLineFlag::TypeName.
+  static absl::string_view TypeName(const CommandLineFlag& flag);
 };
 
 }  // namespace flags_internal