refs #142, autodetect dirent::d_type and add GHC_OS_SOLARIS detection

Took 3 hours 8 minutes

Author: gulrak

include/ghc/filesystem.hpp

@@ -67,6 +67,8 @@
 #define GHC_OS_WIN32
 #elif defined(__CYGWIN__)
 #define GHC_OS_CYGWIN
+#elif defined(__sun) && defined(__SVR4)
+#define GHC_OS_SOLARIS
 #elif defined(__svr4__)
 #define GHC_OS_SYS5R4
 #elif defined(BSD)
@@ -76,7 +78,6 @@
 #include <wasi/api.h>
 #elif defined(__QNX__)
 #define GHC_OS_QNX
-#define GHC_NO_DIRENT_D_TYPE
 #else
 #error "Operating system currently not supported!"
 #endif
@@ -1298,6 +1299,49 @@ GHC_FS_API std::error_code make_error_code(portable_error err);
 GHC_FS_API std::error_code make_system_error(uint32_t err = 0);
 #else
 GHC_FS_API std::error_code make_system_error(int err = 0);
+
+template <typename T, typename = int>
+struct has_d_type : std::false_type{};
+
+template <typename T>
+struct has_d_type<T, decltype((void)T::d_type, 0)> : std::true_type {};
+
+template <typename T>
+GHC_INLINE file_type file_type_from_dirent_impl(const T&, std::false_type)
+{
+    return file_type::unknown;
+}
+
+template <typename T>
+GHC_INLINE file_type file_type_from_dirent_impl(const T& t, std::true_type)
+{
+    switch (t.d_type) {
+        case DT_BLK:
+            return file_type::block;
+        case DT_CHR:
+            return file_type::character;
+        case DT_DIR:
+            return file_type::directory;
+        case DT_FIFO:
+            return file_type::fifo;
+        case DT_LNK:
+            return file_type::symlink;
+        case DT_REG:
+            return file_type::regular;
+        case DT_SOCK:
+            return file_type::socket;
+        case DT_UNKNOWN:
+            return file_type::none;
+        default:
+            return file_type::unknown;
+    }
+}
+
+template <class T>
+GHC_INLINE file_type file_type_from_dirent(const T& t)
+{
+    return file_type_from_dirent_impl(t, has_d_type<T>{});
+}
 #endif
 }  // namespace detail
 
@@ -5658,48 +5702,16 @@ class directory_iterator::impl
 
     void copyToDirEntry()
     {
-#ifdef GHC_NO_DIRENT_D_TYPE
-        _dir_entry._symlink_status = file_status();
-        _dir_entry._status = file_status();
-#else
         _dir_entry._symlink_status.permissions(perms::unknown);
-        switch (_entry->d_type) {
-            case DT_BLK:
-                _dir_entry._symlink_status.type(file_type::block);
-                break;
-            case DT_CHR:
-                _dir_entry._symlink_status.type(file_type::character);
-                break;
-            case DT_DIR:
-                _dir_entry._symlink_status.type(file_type::directory);
-                break;
-            case DT_FIFO:
-                _dir_entry._symlink_status.type(file_type::fifo);
-                break;
-            case DT_LNK:
-                _dir_entry._symlink_status.type(file_type::symlink);
-                break;
-            case DT_REG:
-                _dir_entry._symlink_status.type(file_type::regular);
-                break;
-            case DT_SOCK:
-                _dir_entry._symlink_status.type(file_type::socket);
-                break;
-            case DT_UNKNOWN:
-                _dir_entry._symlink_status.type(file_type::none);
-                break;
-            default:
-                _dir_entry._symlink_status.type(file_type::unknown);
-                break;
-        }
-        if (_entry->d_type != DT_LNK) {
+        auto ft = detail::file_type_from_dirent(*_entry);
+        _dir_entry._symlink_status.type(ft);
+        if (ft != file_type::symlink) {
             _dir_entry._status = _dir_entry._symlink_status;
         }
         else {
             _dir_entry._status.type(file_type::none);
             _dir_entry._status.permissions(perms::unknown);
         }
-#endif
         _dir_entry._file_size = static_cast<uintmax_t>(-1);
         _dir_entry._hard_link_count = static_cast<uintmax_t>(-1);
         _dir_entry._last_write_time = 0;