From b20866c4b3aa1446efda252bd5c3fa54f68c5d7f Mon Sep 17 00:00:00 2001 From: Mattias Engdegård Date: Sun, 24 Mar 2024 18:18:41 +0100 Subject: Better `sort` ignored-return-value warning * lisp/emacs-lisp/bytecomp.el (byte-compile-form) (bytecomp--actually-important-return-value-p): Special handling of `sort` that takes into account that it may return an important value depending on the :in-place keyword argument. --- lisp/emacs-lisp/bytecomp.el | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/lisp/emacs-lisp/bytecomp.el b/lisp/emacs-lisp/bytecomp.el index 7af568cfe34..2b5eb34e571 100644 --- a/lisp/emacs-lisp/bytecomp.el +++ b/lisp/emacs-lisp/bytecomp.el @@ -3445,6 +3445,7 @@ lambda-expression." ((and (or sef (function-get (car form) 'important-return-value)) ;; Don't warn for arguments to `ignore'. (not (eq byte-compile--for-effect 'for-effect-no-warn)) + (bytecomp--actually-important-return-value-p form) (byte-compile-warning-enabled-p 'ignored-return-value (car form))) (byte-compile-warn-x @@ -3471,6 +3472,15 @@ lambda-expression." (if byte-compile--for-effect (byte-compile-discard))))) +(defun bytecomp--actually-important-return-value-p (form) + "Whether FORM is really a call with a return value that should not go unused. +This assumes the function has the `important-return-value' property." + (cond ((eq (car form) 'sort) + ;; For `sort', we only care about non-destructive uses. + (and (zerop (% (length form) 2)) ; new-style call + (not (plist-get (cddr form) :in-place)))) + (t t))) + (let ((important-return-value-fns '( ;; These functions are side-effect-free except for the @@ -3478,9 +3488,11 @@ lambda-expression." mapcar mapcan mapconcat assoc plist-get plist-member - ;; It's safe to ignore the value of `sort' and `nreverse' + ;; It's safe to ignore the value of `nreverse' ;; when used on arrays, but most calls pass lists. - nreverse sort + nreverse + + sort ; special handling (non-destructive calls only) match-data -- cgit v1.2.3