Export of internal Abseil changes

--
0c8848ebedc07470c7ab647a5bb8949481540ce9 by Dino Radakovic <dinor@google.com>:

Define absl::base_internal::invoke using std::invoke when C++ >= 17

PiperOrigin-RevId: 439880834
Change-Id: I3622fcf473501d54c57575118a11d54c19573446
GitOrigin-RevId: 0c8848ebedc07470c7ab647a5bb8949481540ce9

absl/base/internal/invoke.h

@@ -14,6 +14,8 @@
 //
 //
 // absl::base_internal::invoke(f, args...) is an implementation of
 // absl::base_internal::invoke(f, args...) is an implementation of
 // INVOKE(f, args...) from section [func.require] of the C++ standard.
 // INVOKE(f, args...) from section [func.require] of the C++ standard.
+// When compiled as C++17 and later versions, it is implemented as an alias of
+// std::invoke.
 //
 //
 // [func.require]
 // [func.require]
 // Define INVOKE (f, t1, t2, ..., tN) as follows:
 // Define INVOKE (f, t1, t2, ..., tN) as follows:
@@ -35,6 +37,25 @@
 #ifndef ABSL_BASE_INTERNAL_INVOKE_H_
 #ifndef ABSL_BASE_INTERNAL_INVOKE_H_
 #define ABSL_BASE_INTERNAL_INVOKE_H_
 #define ABSL_BASE_INTERNAL_INVOKE_H_
 
 
+#include "absl/base/config.h"
+
+#if __cplusplus >= 201703L || (defined(_MSVC_LANG) && _MSVC_LANG >= 201703L)
+
+#include <functional>
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace base_internal {
+
+using std::invoke;
+using std::invoke_result_t;
+
+}  // namespace base_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#else  // __cplusplus >= 201703L
+
 #include <algorithm>
 #include <algorithm>
 #include <type_traits>
 #include <type_traits>
 #include <utility>
 #include <utility>
@@ -184,4 +205,6 @@ invoke_result_t<F, Args...> invoke(F&& f, Args&&... args) {
 ABSL_NAMESPACE_END
 ABSL_NAMESPACE_END
 }  // namespace absl
 }  // namespace absl
 
 
+#endif  // __cplusplus >= 201703L
+
 #endif  // ABSL_BASE_INTERNAL_INVOKE_H_
 #endif  // ABSL_BASE_INTERNAL_INVOKE_H_