Re: cc-vars.el

[Dave Love <d.love@dl.ac.uk>]

Miles Bader <miles@lsi.nec.co.jp> writes:

> _That_ sort of change is pretty easy, and has the advantage of working
> even with old compilers that don't special case it (they'll just emit a
> warning like before, but the generated code will be the same).

Exactly.  This was it.  I think it was the only diff needed, but I'm
not sure it didn't depend on another change.

As far as I remember, someone didn't like it because it wasn't
general, i.e. it doesn't work with all conditionals.  I don't think
that matters if it's documented.

*** bytecomp.el	23 Jul 2001 16:02:49 -0000	2.84
--- bytecomp.el	19 Nov 2002 11:29:15 -0000
*************** If FORM is a lambda or a macro, byte-com
*** 3213,3231 ****
  
  (defun byte-compile-if (form)
    (byte-compile-form (car (cdr form)))
!   (if (null (nthcdr 3 form))
!       ;; No else-forms
!       (let ((donetag (byte-compile-make-tag)))
! 	(byte-compile-goto-if nil for-effect donetag)
! 	(byte-compile-form (nth 2 form) for-effect)
! 	(byte-compile-out-tag donetag))
!     (let ((donetag (byte-compile-make-tag)) (elsetag (byte-compile-make-tag)))
!       (byte-compile-goto 'byte-goto-if-nil elsetag)
!       (byte-compile-form (nth 2 form) for-effect)
!       (byte-compile-goto 'byte-goto donetag)
!       (byte-compile-out-tag elsetag)
!       (byte-compile-body (cdr (cdr (cdr form))) for-effect)
!       (byte-compile-out-tag donetag)))
    (setq for-effect nil))
  
  (defun byte-compile-cond (clauses)
--- 3213,3258 ----
  
  (defun byte-compile-if (form)
    (byte-compile-form (car (cdr form)))
!   ;; Check whether we have `(if (fboundp ...' or `(if (boundp ...'
!   (let* ((clause (nth 1 form))
! 	 (fbound (if (eq 'fboundp (car-safe clause))
! 		     (and (eq 'quote (car-safe (nth 1 clause)))
! 			  (nth 1 (nth 1 clause))))) ; the relevant symbol
! 	 (bound (if (eq 'boundp (car-safe clause))
! 		    (and (eq 'quote (car-safe (nth 1 clause)))
! 			 (nth 1 (nth 1 clause)))))) ; the relevant symbol
!     (if (null (nthcdr 3 form))
! 	;; No else-forms
! 	(let ((donetag (byte-compile-make-tag)))
! 	  (byte-compile-goto-if nil for-effect donetag)
! 	  (cond (bound (let ((byte-compile-bound-variables
! 			      (cons bound
! 				    byte-compile-bound-variables)))
! 			 (byte-compile-form (nth 2 form) for-effect)))
! 		(fbound (byte-compile-form (nth 2 form) for-effect)
! 			(setq byte-compile-unresolved-functions
! 			      (delq (assq fbound
! 					  byte-compile-unresolved-functions)
! 				    byte-compile-unresolved-functions)))
! 		(t (byte-compile-form (nth 2 form) for-effect)))
! 	  (byte-compile-out-tag donetag))
!       (let ((donetag (byte-compile-make-tag))
! 	    (elsetag (byte-compile-make-tag)))
! 	(byte-compile-goto 'byte-goto-if-nil elsetag)
! 	(cond (bound (let ((byte-compile-bound-variables
! 			    (cons bound
! 				  byte-compile-bound-variables)))
! 		       (byte-compile-form (nth 2 form) for-effect)))
! 	      (fbound (byte-compile-form (nth 2 form) for-effect)
! 		      (setq byte-compile-unresolved-functions
! 			    (delq (assq fbound
! 					byte-compile-unresolved-functions)
! 				  byte-compile-unresolved-functions)))
! 	      (t (byte-compile-form (nth 2 form) for-effect)))
! 	(byte-compile-goto 'byte-goto donetag)
! 	(byte-compile-out-tag elsetag)
! 	(byte-compile-body (cdr (cdr (cdr form))) for-effect)
! 	(byte-compile-out-tag donetag))))
    (setq for-effect nil))
  
  (defun byte-compile-cond (clauses)