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Elide broken but unnecessary if optimisations

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* lisp/emacs-lisp/byte-opt.el (byte-optimize-if):
Remove explicit clauses purposing to simplify

    (if X nil t) -> (not X)
    (if X t nil) -> (not (not X))

but never did so because of a coding mistake (eq instead of equal),
found by a recently added warning.  They weren't actually needed
thanks to the optimiser's fixpoint iteration: we eventually get the
same results through

    (if X nil t) -> (if (not X) t nil) -> (if (not X) t) -> (not X)
    (if X t nil) -> (if X t) -> (not (not X))
This commit is contained in:
Mattias Engdegård 2022-12-16 15:56:04 +01:00
parent 17d65c99cd
commit 13aa376e93
1 changed files with 2 additions and 5 deletions
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7
lisp/emacs-lisp/byte-opt.el
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@ -1297,11 +1297,8 @@ See Info node `(elisp) Integer Basics'."
(if else (if else
`(progn ,condition ,@else) `(progn ,condition ,@else)
condition)) condition))
;; (if X nil t) -> (not X) ;; (if X t) -> (not (not X))
((and (eq then nil) (eq else '(t))) ((and (eq then t) (null else))
`(not ,condition))
;; (if X t [nil]) -> (not (not X))
((and (eq then t) (or (null else) (eq else '(nil))))
`(not ,(byte-opt--negate condition))) `(not ,(byte-opt--negate condition)))
;; (if VAR VAR X...) -> (or VAR (progn X...)) ;; (if VAR VAR X...) -> (or VAR (progn X...))
((and (symbolp condition) (eq condition then)) ((and (symbolp condition) (eq condition then))