Inline some Abseil symbols that are from namespace std

PiperOrigin-RevId: 930615843
Change-Id: Ia058cf5c61502156bc4ec3c6dcd4b48ad5570616

absl/memory/memory.h

diff --git a/absl/memory/memory.h b/absl/memory/memory.h
index 4719364..d364df8 100644
--- a/absl/memory/memory.h
+++ b/absl/memory/memory.h
@@ -94,7 +94,7 @@
 // the C++14's `std::make_unique`. Now that C++11 support has been sunsetted,
 // `absl::make_unique` simply uses the STL-provided implementation. New code
 // should use `std::make_unique`.
-using std::make_unique;
+using std::make_unique ABSL_REFACTOR_INLINE;
 
 #if defined(__cpp_lib_smart_ptr_for_overwrite) && \
     __cpp_lib_smart_ptr_for_overwrite >= 202002L

absl/meta/type_traits.h

diff --git a/absl/meta/type_traits.h b/absl/meta/type_traits.h
index 9f52202..be55e52 100644
--- a/absl/meta/type_traits.h
+++ b/absl/meta/type_traits.h
@@ -151,6 +151,7 @@
 template <class T>
 using decay_t ABSL_DEPRECATE_AND_INLINE() = std::decay_t<T>;
 
+// Avoid inlining since the inliner cannot handle default arguments well.
 template <bool C, class T = void>
 using enable_if_t [[deprecated("Use std::enable_if_t instead.")]] =
     std::enable_if_t<C, T>;

absl/types/optional.h

diff --git a/absl/types/optional.h b/absl/types/optional.h
index c70efb1..a5b15b8 100644
--- a/absl/types/optional.h
+++ b/absl/types/optional.h
@@ -56,12 +56,13 @@
   return std::make_optional<T>(il, std::forward<Args>(args)...);
 }
 
-using std::nullopt;
+using std::nullopt ABSL_REFACTOR_INLINE;
 
 using nullopt_t ABSL_REFACTOR_INLINE
     = std::nullopt_t;
 
-using std::optional;
+using std::optional ABSL_REFACTOR_INLINE;
+
 ABSL_NAMESPACE_END
 }  // namespace absl