is there any way to stop GDC complain about non-utf source encoding?

[Dejan Lekic via D.gnu]

You do not have a choice mate, D source files must be UTF-8.

Check this page: http://dlang.org/lex

Let me extract the relevant part of it:

Source Text
D source text can be in one of the following formats:

     ASCII
     UTF-8
     UTF-16BE
     UTF-16LE
     UTF-32BE
     UTF-32LE