std::result_of removed in C++20 (#115)

open-telemetry · Jun 16, 2020 · 49eee20 · 49eee20
1 parent b472384
commit 49eee20
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Showing 2 changed files with 13 additions and 0 deletions.
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -22,6 +22,13 @@ include(CTest)
 
 find_package(Threads)
 
+if(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+  # Options for Visual C++ compiler:
+  # /Zc:__cplusplus - report an updated value for recent C++ language standards.
+  # Without this option MSVC returns the value of __cplusplus="199711L"
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /Zc:__cplusplus")
+endif()
+
 if(WITH_PROTOBUF)
   set(protobuf_MODULE_COMPATIBLE ON)
   find_package(Protobuf CONFIG NAMES protobuf)

diff --git a/api/include/opentelemetry/nostd/function_ref.h b/api/include/opentelemetry/nostd/function_ref.h
@@ -63,7 +63,13 @@ class function_ref<R(Args...)>
       typename std::enable_if<!std::is_same<function_ref, typename std::decay<F>::type>::value,
                               int>::type = 0,
       typename std::enable_if<
+#if (__cplusplus >= 201703L)
+          // std::result_of deprecated in C++17, removed in C++20
+          std::is_convertible<typename std::invoke_result<F, Args...>::type, R>::value,
+#else
+          // std::result_of since C++11
           std::is_convertible<typename std::result_of<F &(Args...)>::type, R>::value,
+#endif
           int>::type = 0>
   function_ref(F &&f)
   {