optional Windows wchar_t/wstring support

Squashed commit of the following:

commit f4a85d2
Author: Steffen Schümann <[email protected]>
Date:   Sun May 19 10:02:22 2019 +0200

    refs #17, refs #18, Missing use of alloc in fromUtf8 (fixed on master) and initialization order issue.

commit aa1cb70
Author: Steffen Schümann <[email protected]>
Date:   Sun May 19 09:46:02 2019 +0200

    refs #18, fighting VS2015 sfinae issues

commit 15788d8
Author: Steffen Schümann <[email protected]>
Date:   Sat May 18 10:35:25 2019 +0200

    refs #17, work on wchar_t/wstring support on Windows.

README.md

@@ -446,16 +446,28 @@ to the expected behavior.
 
 ## Release Notes
 
-### v1.1.5 (wip)
+### v1.1.99 (wip)
 
 * Added MingW 32/64 and Visual Studio 2015 builds to the CI configuration.
 * Fixed additional compilation issues on MingW.
+* Pull request ([#13](https://github.com/gulrak/filesystem/pull/13)), set
+  minimum required CMake version to 3.7.2 (as in Debian 8).
+* Pull request ([#14](https://github.com/gulrak/filesystem/pull/14)), added
+  support for a make install target.
 * Bugfix for ([#15](https://github.com/gulrak/filesystem/issues/15)), the
   forward/impl way of using `ghc::filesystem` missed a `<vector>` include
   in the windows case.
 * Bugfix for ([#16](https://github.com/gulrak/filesystem/issues/16)),
   VS2019 didn't like the old size dispatching in the utf8 decoder, so it
   was changed to a sfinae based approach.
+* New feature ([#17](https://github.com/gulrak/filesystem/issues/17)), optional
+  support for standard conforming `wchar_t/std::wstring` interface when
+  compiling on Windows with defined `GHC_WIN_WSTRING_STRING_TYPE`, this is
+  default when using the `ghc/fs_std*.hpp` header, to enhance compatibility.
+* Pull request ([#20](https://github.com/gulrak/filesystem/pull/14)), fix for
+  file handle leak in `fs::copy_file`.
+* Coverage now checked in CI (~95% line coverage).
+
 
 ### [v1.1.4](https://github.com/gulrak/filesystem/releases/tag/v1.1.4)
 

examples/dir.cpp

@@ -1,17 +1,21 @@
-#include <iostream>
-#include <iomanip>
 #include <chrono>
+#include <iomanip>
+#include <iostream>
 #include <string>
 
-#if defined(__cplusplus) && __cplusplus >= 201703L && defined(__has_include) && __has_include(<filesystem>)
+#if defined(__cplusplus) && __cplusplus >= 201703L && defined(__has_include)
+#if __has_include(<filesystem>)
+#define GHC_USE_STD_FS
 #include <filesystem>
 namespace fs = std::filesystem;
-#else
+#endif
+#endif
+#ifndef GHC_USE_STD_FS
 #include <ghc/filesystem.hpp>
 namespace fs = ghc::filesystem;
 #endif
 
-template<typename TP>
+template <typename TP>
 std::time_t to_time_t(TP tp)
 {
     // Based on trick from: Nico Josuttis, C++17 - The Complete Guide
@@ -23,8 +27,8 @@ static std::string perm_to_str(fs::perms prms)
 {
     std::string result;
     result.reserve(9);
-    for(int i = 0; i < 9; ++i) {
-        result = ((static_cast<int>(prms) & (1<<i)) ? "xwrxwrxwr"[i] : '-') + result;
+    for (int i = 0; i < 9; ++i) {
+        result = ((static_cast<int>(prms) & (1 << i)) ? "xwrxwrxwr"[i] : '-') + result;
     }
     return result;
 }
@@ -33,27 +37,24 @@ int main(int argc, char* argv[])
 {
 #ifdef GHC_FILESYSTEM_VERSION
     fs::u8arguments u8guard(argc, argv);
-    if(!u8guard.valid()) {
+    if (!u8guard.valid()) {
         std::cerr << "Invalid character encoding, UTF-8 based encoding needed." << std::endl;
         std::exit(EXIT_FAILURE);
     }
 #endif
-    if(argc > 2) {
+    if (argc > 2) {
         std::cerr << "USAGE: dir <path>" << std::endl;
         exit(1);
     }
     fs::path dir{"."};
-    if(argc == 2) {
+    if (argc == 2) {
         dir = fs::u8path(argv[1]);
     }
-    for(auto de : fs::directory_iterator(dir)) {
+    for (auto de : fs::directory_iterator(dir)) {
         auto ft = to_time_t(de.last_write_time());
         auto ftm = *std::localtime(&ft);
-        std::cout << (de.is_directory() ? "d" : "-") << perm_to_str(de.symlink_status().permissions()) << "  "
-                  << std::setw(8) << (de.is_directory() ? "-" : std::to_string(de.file_size())) << "  "
-                  << std::put_time(&ftm, "%Y-%m-%d %H:%M:%S") << "  "
-                  << de.path().filename().string() 
-                  << std::endl;
+        std::cout << (de.is_directory() ? "d" : "-") << perm_to_str(de.symlink_status().permissions()) << "  " << std::setw(8) << (de.is_directory() ? "-" : std::to_string(de.file_size())) << "  " << std::put_time(&ftm, "%Y-%m-%d %H:%M:%S") << "  "
+                  << de.path().filename().string() << std::endl;
     }
     return 0;
 }

examples/du.cpp

@@ -2,10 +2,14 @@
 #include <iomanip>
 #include <chrono>
 
-#if defined(__cplusplus) && __cplusplus >= 201703L && defined(__has_include) && __has_include(<filesystem>)
+#if defined(__cplusplus) && __cplusplus >= 201703L && defined(__has_include)
+#if __has_include(<filesystem>)
+#define GHC_USE_STD_FS
 #include <filesystem>
 namespace fs = std::filesystem;
-#else
+#endif
+#endif
+#ifndef GHC_USE_STD_FS
 #include <ghc/filesystem.hpp>
 namespace fs = ghc::filesystem;
 #endif