Index: doxygen-1.9.4/filesystem/filesystem.hpp
===================================================================
--- doxygen-1.9.4.orig/filesystem/filesystem.hpp
+++ doxygen-1.9.4/filesystem/filesystem.hpp
@@ -56,6 +56,8 @@
 #define GHC_OS_MACOS
 #elif defined(__linux__)
 #define GHC_OS_LINUX
+#elif defined(__GNU__)
+#define GHC_OS_GNU
 #if defined(__ANDROID__)
 #define GHC_OS_ANDROID
 #endif
@@ -4081,6 +4083,13 @@ GHC_INLINE path current_path(std::error_
         return path();
     }
     return path(std::wstring(buffer.get()), path::native_format);
+#elif defined(GHC_OS_GNU)
+    char* buffer = ::getcwd (NULL, 0);
+    if (buffer == nullptr) {
+        ec = detail::make_system_error();
+        return path();
+    }
+    return path(buffer);
 #else
     size_t pathlen = static_cast<size_t>(std::max(int(::pathconf(".", _PC_PATH_MAX)), int(PATH_MAX)));
     std::unique_ptr<char[]> buffer(new char[pathlen + 1]);