Why does byte-compile-file copy the input file to a different buffer?

[Alan Mackenzie <acm@muc.de>]

Hello, Emacs.

On executing a byte-compile-file command, rather than working on the
file's buffer directly, the byte compiler first copies the buffer/file
into another buffer with a boring name like " *Compiler Input*" or "
*Compiler Input*-1".

Why does it do this?  It makes it difficult, in the reader, to determine
the identity of the actual source buffer.  (Yes, I have reasons for
wanting to do this.)

Would it not be simpler just to compile directly from the source buffer,
thus avoiding a needless copying and making it clear what the actual
source buffer is?

-- 
Alan Mackenzie (Nuremberg, Germany).