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(byte-optimize-form-code-walker): Treat `ignore' specially--prevent

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warnings about functions called for effect, in its args.
Don't warn when `pop' is used for effect.
This commit is contained in:
Richard M. Stallman 2002-10-14 01:33:40 +00:00
parent 7dab57b625
commit 8c26d7b356
1 changed files with 20 additions and 1 deletions
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21
lisp/emacs-lisp/byte-opt.el
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@ -501,6 +501,13 @@
(cons (byte-optimize-form (nth 1 form) nil)
(cdr (cdr form)))))
((eq fn 'ignore)
;; Don't treat the args to `ignore' as being
;; computed for effect. We want to avoid the warnings
;; that might occur if they were treated that way.
;; However, don't actually bother calling `ignore'.
`(prog1 nil . ,(mapcar 'byte-optimize-form (cdr form))))
;; If optimization is on, this is the only place that macros are
;; expanded. If optimization is off, then macroexpansion happens
;; in byte-compile-form. Otherwise, the macros are already expanded
@ -526,9 +533,21 @@
((and for-effect (setq tmp (get fn 'side-effect-free))
(or byte-compile-delete-errors
(eq tmp 'error-free)
;; Detect the expansion of (pop foo).
;; There is no need to compile the call to `car' there.
(and (eq fn 'car)
(eq (car-safe (cadr form)) 'prog1)
(let ((var (cadr (cadr form)))
(last (nth 2 (cadr form))))
(and (symbolp var)
(null (nthcdr 3 (cadr form)))
(eq (car-safe last) 'setq)
(eq (cadr last) var)
(eq (car-safe (nth 2 last)) 'cdr)
(eq (cadr (nth 2 last)) var))))
(progn
(byte-compile-warn "`%s' called for effect"
(prin1-to-string form))
(prin1-to-string (car form)))
nil)))
(byte-compile-log " %s called for effect; deleted" fn)
;; appending a nil here might not be necessary, but it can't hurt.