(defcustom emacs-lisp-file-regexp "\\.el\\'"
"Regexp which matches Emacs Lisp source files.
-If you change this, you might want to set `byte-compile-dest-file-function'."
+If you change this, you might want to set `byte-compile-dest-file-function'.
+\(Note that the assumption of a \".elc\" suffix for compiled files
+is hard-coded in various places in Emacs.)"
+ ;; Eg is_elc in Fload.
:group 'bytecomp
:type 'regexp)
(defcustom byte-compile-dest-file-function nil
"Function for the function `byte-compile-dest-file' to call.
It should take one argument, the name of an Emacs Lisp source
-file name, and return the name of the compiled file."
+file name, and return the name of the compiled file.
+\(Note that the assumption that the source and compiled files
+are found in the same directory is hard-coded in various places in Emacs.)"
+ ;; Eg load-prefer-newer, documentation lookup IIRC.
:group 'bytecomp
:type '(choice (const nil) function)
:version "23.2")
"Convert an Emacs Lisp source file name to a compiled file name.
If `byte-compile-dest-file-function' is non-nil, uses that
function to do the work. Otherwise, if FILENAME matches
-`emacs-lisp-file-regexp' (by default, files with the extension `.el'),
-adds `c' to it; otherwise adds `.elc'."
+`emacs-lisp-file-regexp' (by default, files with the extension \".el\"),
+replaces the matching part (and anything after it) with \"\.elc\";
+otherwise adds \".elc\"."
(if byte-compile-dest-file-function
(funcall byte-compile-dest-file-function filename)
(setq filename (file-name-sans-versions