Fix building of samples due to incosistent c++ standard

Author: SergiusTheBest

samples/CXX11/CMakeLists.txt

@@ -1,4 +1,4 @@
-if (CMAKE_VERSION VERSION_GREATER_EQUAL 3.3.0)
+if (NOT CMAKE_VERSION VERSION_LESS 3.3.0)
     cmake_minimum_required(VERSION 3.3)
 
     if(cxx_std_11 IN_LIST CMAKE_CXX_COMPILE_FEATURES)

samples/CXX11/Main.cpp

@@ -14,13 +14,19 @@ int main()
 {
     plog::init<plog::TxtFormatter>(plog::debug, plog::streamStdOut); // Initialize logging
 
-    std::unordered_map<std::string, int> unorderedMap = { {"red", 1}, {"green", 2}, {"blue", 4} };
+    std::unordered_map<std::string, int> unorderedMap;
+    unorderedMap["red"] = 1;
+    unorderedMap["green"] = 2;
+    unorderedMap["blue"] = 4;
     PLOG_INFO << unorderedMap;
 
-    std::unordered_set<std::string> unorderedSet = { "red", "green", "blue" };
+    std::unordered_set<std::string> unorderedSet;
+    unorderedSet.insert("red");
+    unorderedSet.insert("green");
+    unorderedSet.insert("blue");
     PLOG_INFO << unorderedSet;
 
-    std::array<int, 4> array = {1, 2, 3, 4};
+    std::array<int, 4> array = {{1, 2, 3, 4}};
     PLOG_INFO << array;
 
     return 0;

samples/CXX17/CMakeLists.txt

@@ -1,7 +1,12 @@
-if (CMAKE_VERSION VERSION_GREATER_EQUAL 3.3.0)
+if (NOT CMAKE_VERSION VERSION_LESS 3.3.0)
     cmake_minimum_required(VERSION 3.3)
 
-    if(cxx_std_17 IN_LIST CMAKE_CXX_COMPILE_FEATURES)
+    # Unfortunately cxx_std_17 in CMAKE_CXX_COMPILE_FEATURES is not reliable, so check include files
+    include(CheckIncludeFileCXX)
+    CHECK_INCLUDE_FILE_CXX("string_view" HAS_STRING_VIEW)
+    CHECK_INCLUDE_FILE_CXX("filesystem" HAS_FILESYSTEM)
+
+    if(HAS_STRING_VIEW AND HAS_FILESYSTEM)
         add_executable(CXX17 Main.cpp)
         target_link_libraries(CXX17 plog::plog)
         set_target_properties(CXX17 PROPERTIES FOLDER Samples CXX_STANDARD 17 CXX_STANDARD_REQUIRED ON)