BUG? UTF-8 functions.php kills an entire site

Hi, I saved my theme’s functions.php in UTF-8, then the whole site went blank.

When I change the file’s encoding back to 8Bit, everything get back to normal.

But I have to use UTF-8 for functions.php to display some Asian characters.

Other files in my theme are all UTF-8 encoded and work just fine.

I guess this is a bug. Any suggestions?

P.S.: I’m new here. Could anyone tell me how to submit a suspected bug to the develop team?