fix CMakeLists.txt bug

Author: sewenew

CMakeLists.txt

@@ -35,10 +35,21 @@ set_target_properties(${STATIC_LIB} PROPERTIES CLEAN_DIRECT_OUTPUT 1)
 set_target_properties(${SHARED_LIB} PROPERTIES CLEAN_DIRECT_OUTPUT 1)
 
 # Some special headers.
-include(CheckIncludeFileCXX)
-check_include_file_cxx(string_view HAVE_STRING_VIEW)
-check_include_file_cxx(optional HAVE_OPTIONAL)
-configure_file(${CMAKE_CURRENT_SOURCE_DIR}/config.h.in ${PROJECT_SOURCE_DIR}/config.h)
+try_compile(HAVE_STRING_VIEW
+            "${CMAKE_CURRENT_BINARY_DIR}/try_compile"
+            "${CMAKE_CURRENT_SOURCE_DIR}/try_compile/try_string_view.cpp")
+
+if (HAVE_STRING_VIEW)
+    add_definitions(-DHAVE_STRING_VIEW)
+endif()
+
+try_compile(HAVE_OPTIONAL
+            "${CMAKE_CURRENT_BINARY_DIR}/try_compile"
+            "${CMAKE_CURRENT_SOURCE_DIR}/try_compile/try_optional.cpp")
+
+if (HAVE_OPTIONAL)
+    add_definitions(-DHAVE_OPTIONAL)
+endif()
 
 add_subdirectory(test)
 

config.h.in

@@ -21,8 +21,6 @@
 #include <string>
 #include <type_traits>
 
-#include "config.h"
-
 #ifdef HAVE_STRING_VIEW
 
 #include <string_view>

src/sw/redis++/utils.h

@@ -6,8 +6,6 @@ else()
     cmake_minimum_required(VERSION 2.8.0)
 endif()
 
-set(CMAKE_CXX_FLAGS "-std=c++11 -Wall -W -Werror -fPIC")
-
 set(PROJECT_SOURCE_DIR ${PROJECT_SOURCE_DIR}/src/sw/redis++)
 
 file(GLOB PROJECT_SOURCE_FILES "${PROJECT_SOURCE_DIR}/*.cpp")

test/CMakeLists.txt

@@ -0,0 +1,9 @@
+#include <optional>
+
+std::optional func() {
+    return {};
+}
+
+int main() {
+    return 0;
+}

try_compile/try_optional.cpp

@@ -0,0 +1,9 @@
+#include <string_view>
+
+std::string_view func() {
+    return {};
+}
+
+int main() {
+    return 0;
+}