1 files changed, 70 insertions, 0 deletions
diff --git a/src/fmt/support/cmake/cxx14.cmake b/src/fmt/support/cmake/cxx14.cmake
new file mode 100644
index 000000000..16ff57541
--- /dev/null
+++ b/src/fmt/support/cmake/cxx14.cmake
@@ -0,0 +1,70 @@
+# C++14 feature support detection
+
+include(CheckCXXSourceCompiles)
+include(CheckCXXCompilerFlag)
+
+if (NOT CMAKE_CXX_STANDARD)
+  set(CMAKE_CXX_STANDARD 11)
+endif()
+message(STATUS "CXX_STANDARD: ${CMAKE_CXX_STANDARD}")
+
+if (CMAKE_CXX_STANDARD EQUAL 20)
+  check_cxx_compiler_flag(-std=c++20 has_std_20_flag)
+  check_cxx_compiler_flag(-std=c++2a has_std_2a_flag)
+
+  if (has_std_20_flag)
+    set(CXX_STANDARD_FLAG -std=c++20)
+  elseif (has_std_2a_flag)
+    set(CXX_STANDARD_FLAG -std=c++2a)
+  endif ()
+elseif (CMAKE_CXX_STANDARD EQUAL 17)
+  check_cxx_compiler_flag(-std=c++17 has_std_17_flag)
+  check_cxx_compiler_flag(-std=c++1z has_std_1z_flag)
+
+  if (has_std_17_flag)
+    set(CXX_STANDARD_FLAG -std=c++17)
+  elseif (has_std_1z_flag)
+    set(CXX_STANDARD_FLAG -std=c++1z)
+  endif ()
+elseif (CMAKE_CXX_STANDARD EQUAL 14)
+  check_cxx_compiler_flag(-std=c++14 has_std_14_flag)
+  check_cxx_compiler_flag(-std=c++1y has_std_1y_flag)
+
+  if (has_std_14_flag)
+    set(CXX_STANDARD_FLAG -std=c++14)
+  elseif (has_std_1y_flag)
+    set(CXX_STANDARD_FLAG -std=c++1y)
+  endif ()
+elseif (CMAKE_CXX_STANDARD EQUAL 11)
+  check_cxx_compiler_flag(-std=c++11 has_std_11_flag)
+  check_cxx_compiler_flag(-std=c++0x has_std_0x_flag)
+
+  if (has_std_11_flag)
+    set(CXX_STANDARD_FLAG -std=c++11)
+  elseif (has_std_0x_flag)
+    set(CXX_STANDARD_FLAG -std=c++0x)
+  endif ()
+endif ()
+
+set(CMAKE_REQUIRED_FLAGS ${CXX_STANDARD_FLAG})
+
+# Check if user-defined literals are available
+check_cxx_source_compiles("
+  void operator\"\" _udl(long double);
+  int main() {}"
+  SUPPORTS_USER_DEFINED_LITERALS)
+if (NOT SUPPORTS_USER_DEFINED_LITERALS)
+  set (SUPPORTS_USER_DEFINED_LITERALS OFF)
+endif ()
+
+# Check if <variant> is available
+set(CMAKE_REQUIRED_FLAGS -std=c++1z)
+check_cxx_source_compiles("
+  #include <variant>
+  int main() {}"
+  FMT_HAS_VARIANT)
+if (NOT FMT_HAS_VARIANT)
+  set (FMT_HAS_VARIANT OFF)
+endif ()
+
+set(CMAKE_REQUIRED_FLAGS )