Msvc warn fix (#20)

* Remove windows warning, use secure getenv

* Fix typo in last commit

* Fix typo in windows version

* Fix another typo in windows version

* Fixing error, dropping warn suppression

CMakeLists.txt

@@ -13,7 +13,6 @@ if(CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME)
     # Be moderately paranoid with flags
     if(MSVC)
         add_definitions("/W4")
-        add_definitions(-D_CRT_SECURE_NO_WARNINGS)
     else()
         add_definitions("-Wall -Wextra -pedantic")
     endif()

include/CLI/App.hpp

@@ -815,9 +815,25 @@ class App {
         // Get envname options if not yet passed
         for(const Option_p &opt : options_) {
             if(opt->count() == 0 && opt->envname_ != "") {
-                char *ename = std::getenv(opt->envname_.c_str());
-                if(ename != nullptr) {
-                    opt->add_result(std::string(ename));
+                char *buffer = nullptr;
+                std::string ename_string;
+
+                #ifdef _MSC_VER
+                // Windows version
+                size_t sz = 0;
+                if(_dupenv_s(&buffer, &sz, opt->envname_.c_str()) == 0 && buffer != nullptr) {
+                    ename_string = std::string(buffer);
+                    free(buffer);
+                }
+                #else
+                // This also works on Windows, but gives a warning
+                buffer = std::getenv(opt->envname_.c_str());
+                if(buffer != nullptr)
+                    ename_string = std::string(buffer);
+                #endif
+
+                if(!ename_string.empty()) {
+                    opt->add_result(ename_string);
                 }
             }
         }