std.stdio.tmpfile() return shared(_IO_FILE)* and not File

[simendsjo via Digitalmars-d-learn]

Using DMD 2.066 on GNU/Linux x86_64.

This is strange:

import std.stdio;
void main() {
    auto f = tmpfile();
    pragma(msg, typeof(f)); // shared(_IO_FILE)*
}

But stdio.d looks like the following:
    static File tmpfile() @safe

What is going on here?