1 files changed, 151 insertions, 6 deletions

diff --git a/third_party/abseil-cpp/absl/flags/internal/commandlineflag.h b/third_party/abseil-cpp/absl/flags/internal/commandlineflag.h
index ebfe81ba1e..6363c6615b 100644
--- a/third_party/abseil-cpp/absl/flags/internal/commandlineflag.h
+++ b/third_party/abseil-cpp/absl/flags/internal/commandlineflag.h
@@ -16,19 +16,41 @@
 #ifndef ABSL_FLAGS_INTERNAL_COMMANDLINEFLAG_H_
 #define ABSL_FLAGS_INTERNAL_COMMANDLINEFLAG_H_
 
+#include <stddef.h>
+#include <stdint.h>
+
+#include <memory>
+#include <string>
+#include <typeinfo>
+
 #include "absl/base/config.h"
-#include "absl/base/internal/fast_type_id.h"
+#include "absl/base/macros.h"
+#include "absl/flags/config.h"
+#include "absl/flags/marshalling.h"
+#include "absl/strings/string_view.h"
+#include "absl/types/optional.h"
 
 namespace absl {
 ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 
-// An alias for flag fast type id. This value identifies the flag value type
-// similarly to typeid(T), without relying on RTTI being available. In most
+// 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 FlagFastTypeId = absl::base_internal::FastTypeIdType;
+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)
+  return const_cast<std::type_info*>(&typeid(T));
+#else
+  return nullptr;
+#endif
+}
 
 // Options that control SetCommandLineOptionWithMode.
 enum FlagSettingMode {
@@ -43,7 +65,7 @@ enum FlagSettingMode {
   SET_FLAGS_DEFAULT
 };
 
-// Options that control ParseFrom: Source of a value.
+// Options that control SetFromString: Source of a value.
 enum ValueSource {
   // Flag is being set by value specified on a command line.
   kCommandLine,
@@ -55,12 +77,135 @@ enum ValueSource {
 // of a flag produced this flag state from method CommandLineFlag::SaveState().
 class FlagStateInterface {
  public:
-  virtual ~FlagStateInterface();
+  virtual ~FlagStateInterface() {}
 
   // Restores the flag originated this object to the saved state.
   virtual void Restore() const = 0;
 };
 
+// Holds all information for a flag.
+class CommandLineFlag {
+ public:
+  constexpr CommandLineFlag() = default;
+
+  // Not copyable/assignable.
+  CommandLineFlag(const CommandLineFlag&) = delete;
+  CommandLineFlag& operator=(const CommandLineFlag&) = delete;
+
+  // Non-polymorphic access methods.
+
+  // Return true iff flag has type T.
+  template <typename T>
+  inline bool IsOfType() const {
+    return TypeId() == &flags_internal::FlagStaticTypeIdGen<T>;
+  }
+
+  // Attempts to retrieve the flag value. Returns value on success,
+  // absl::nullopt otherwise.
+  template <typename T>
+  absl::optional<T> Get() const {
+    if (IsRetired() || !IsOfType<T>()) {
+      return absl::nullopt;
+    }
+
+    // Implementation notes:
+    //
+    // We are wrapping a union around the value of `T` to serve three purposes:
+    //
+    //  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.
+    //  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
+    //     scope. We do need to destroy U.value, which is constructed by
+    //     CommandLineFlag::Read even though we left it in a moved-from state
+    //     after std::move.
+    //
+    // All of this serves to avoid requiring `T` being default constructible.
+    union U {
+      T value;
+      U() {}
+      ~U() { value.~T(); }
+    };
+    U u;
+
+    Read(&u.value);
+    return std::move(u.value);
+  }
+
+  // Polymorphic access methods
+
+  // 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.
+  virtual bool IsRetired() const { return false; }
+  // 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 FlagStaticTypeId TypeId() const = 0;
+  virtual bool IsModified() const = 0;
+  virtual bool IsSpecifiedOnCommandLine() const = 0;
+  virtual std::string DefaultValue() const = 0;
+  virtual std::string CurrentValue() const = 0;
+
+  // Interfaces to operate on validators.
+  virtual bool ValidateInputValue(absl::string_view value) const = 0;
+
+  // Interface to save flag to some persistent state. Returns current flag state
+  // or nullptr if flag does not support saving and restoring a state.
+  virtual std::unique_ptr<FlagStateInterface> SaveState() = 0;
+
+  // Sets the value of the flag based on specified std::string `value`. If the flag
+  // was successfully set to new value, it returns true. Otherwise, sets `error`
+  // to indicate the error, leaves the flag unchanged, and returns false. There
+  // are three ways to set the flag's value:
+  //  * Update the current flag value
+  //  * 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.
+  virtual bool SetFromString(absl::string_view value,
+                             flags_internal::FlagSettingMode set_mode,
+                             flags_internal::ValueSource source,
+                             std::string* error) = 0;
+
+  // Checks that flags default value can be converted to std::string and back to the
+  // flag's value type.
+  virtual void CheckDefaultValueParsingRoundtrip() const = 0;
+
+ protected:
+  ~CommandLineFlag() = default;
+
+ 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.
+  virtual void Read(void* dst) const = 0;
+};
+
+// This macro is the "source of truth" for the list of supported flag built-in
+// types.
+#define ABSL_FLAGS_INTERNAL_BUILTIN_TYPES(A) \
+  A(bool)                                    \
+  A(short)                                   \
+  A(unsigned short)                          \
+  A(int)                                     \
+  A(unsigned int)                            \
+  A(long)                                    \
+  A(unsigned long)                           \
+  A(long long)                               \
+  A(unsigned long long)                      \
+  A(double)                                  \
+  A(float)                                   \
+  A(std::string)                             \
+  A(std::vector<std::string>)
+
 }  // namespace flags_internal
 ABSL_NAMESPACE_END
 }  // namespace absl