Abseil LTS 2020092320200923

What's New:
* `absl::StatusOr<T>` has been released. See our [blog
  post](https://abseil.io/blog/2020-091021-status) for more
  information.
* Abseil Flags reflection interfaces have been released.
* Abseil Flags memory usage has been significantly optimized.
* Abseil now supports a "hardened" build mode. This build mode enables
  runtime checks that guard against programming errors that may lead
  to security vulnerabilities.

Notable Fixes:
* Sanitizer dynamic annotations like `AnnotateRWLockCreate` that are
  also defined by the compiler sanitizer implementation are no longer
  also defined by Abseil.
* Sanitizer macros are now prefixed with `ABSL_` to avoid naming collisions.
* Sanitizer usage is now automatically detected and no longer requires
  macros like `ADDRESS_SANITIZER` to be defined on the command line.

Breaking Changes:
* Abseil no longer contains a `dynamic_annotations` library. Users
  using a supported build system (Bazel or CMake) are unaffected by
  this, but users manually specifying link libraries may get an error
  about a missing linker input.

Baseline: 7680a5f8efe32de4753baadbd63e74e59d95bac1
Cherry picks: None

1 files changed, 6 insertions, 151 deletions

diff --git a/absl/flags/internal/commandlineflag.h b/absl/flags/internal/commandlineflag.h
index 6363c661..cb46fe2e 100644
--- a/absl/flags/internal/commandlineflag.h
+++ b/absl/flags/internal/commandlineflag.h
@@ -16,41 +16,19 @@
 #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/macros.h"
-#include "absl/flags/config.h"
-#include "absl/flags/marshalling.h"
-#include "absl/strings/string_view.h"
-#include "absl/types/optional.h"
+#include "absl/base/internal/fast_type_id.h"
 
 namespace absl {
 ABSL_NAMESPACE_BEGIN
 namespace flags_internal {
 
-// 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
+// An alias for flag fast type id. This value identifies the flag value type
+// simialarly to typeid(T), 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)
-  return const_cast<std::type_info*>(&typeid(T));
-#else
-  return nullptr;
-#endif
-}
+using FlagFastTypeId = absl::base_internal::FastTypeIdType;
 
 // Options that control SetCommandLineOptionWithMode.
 enum FlagSettingMode {
@@ -65,7 +43,7 @@ enum FlagSettingMode {
   SET_FLAGS_DEFAULT
 };
 
-// Options that control SetFromString: Source of a value.
+// Options that control ParseFrom: Source of a value.
 enum ValueSource {
   // Flag is being set by value specified on a command line.
   kCommandLine,
@@ -77,135 +55,12 @@ 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