Recognize & skip the UTF-8 BOM

[LemonBoy]

I was puzzled when a file downloaded from Godbolt kept telling me there were extraneous characters at the very beginning of the file.

[rohlem]

Wouldn't this fall under the same "only one way to do things"-category as f.e. CRLF line endings?
In which case current compiler behaviour is to reject (though with a more helpful error message), and zig fmt fixes/standardizes the source file.
(see also PR #582 )

[LemonBoy]

Wouldn't this fall under the same "only one way to do things"-category as f.e. CRLF line endings?

UTF-8 with BOM is still UTF-8

zig fmt fixes/standardizes the source file

zig fmt is able to read such files but doesn't preserve the BOM, the status quo is retained