names not demangled in nm --demangle=dlang

[Zheng Luo (Vic) via Digitalmars-d-learn]

Hi,
I built a simple program with dmd a.d and tried to observe 
symbols with nm --demangle=dlang ./a. However, I can observe that 
only part of the symbols (e.g., std.stdio.File.size()) are 
demangled, while others remain in their original name (e.g., 
_D3std5stdio4File8opAssignMFNfSQBdQBcQzZv). Is this a bug of nm? 
Moreover, what is the suggested way to demangle symbol names in 
dlang?

Thanks