I have not heard of this bug before. Can you please file it on https://github.com/Microsoft/dafny?
You asked if there's a better way to create a
Hmm, I was able to recreate your bug (in the most up-to-date version of Dafny). And also find a workaround: don't save the file as an empty file, but instead add an empty comment to the file before saving it:
You asked if there's a better way to create a
.dfy file from within VS. I don't know of a simple way to do it. My (possibly mistaken) understanding is that this functionality requires building a project system plug-in. It's embarrassing that the hardest step in writing a simple Dafny program inside VS is the creation of the file. The best way I know to do it is to create a new text file and then do a Save As. In the Save As dialog, be sure to select "All types" as the type of file, since it will let you add the .dfy extension without VS adding yet another .txt after that.Hmm, I was able to recreate your bug (in the most up-to-date version of Dafny). And also find a workaround: don't save the file as an empty file, but instead add an empty comment to the file before saving it:
//