The encoding was deduced from looking at the source code, feel free to
fix if it's wrong (the docs _and_ the source code).
/**
* g_file_new_for_path:
- * @path: a string containing a relative or absolute path.
+ * @path: a string containing a relative or absolute path. The string
+ * must be encoded in the glib filename encoding.
*
* Constructs a #GFile for a given path. This operation never
* fails, but the returned object might not support any I/O
/**
* g_file_new_for_uri:
- * @uri: a string containing a URI.
+ * @uri: a UTF8 string containing a URI.
*
* Constructs a #GFile for a given URI. This operation never
* fails, but the returned object might not support any I/O