diff options
Diffstat (limited to 'lisp/emacs-lisp/cconv.el')
| -rw-r--r-- | lisp/emacs-lisp/cconv.el | 109 |
1 files changed, 64 insertions, 45 deletions
diff --git a/lisp/emacs-lisp/cconv.el b/lisp/emacs-lisp/cconv.el index 3d6132c9aa6..4507af7a59b 100644 --- a/lisp/emacs-lisp/cconv.el +++ b/lisp/emacs-lisp/cconv.el @@ -253,6 +253,32 @@ Returns a form where all lambdas don't have any free variables." `(internal-make-closure ,args ,envector ,docstring . ,body-new))))) +(defun cconv--remap-llv (new-env var closedsym) + ;; In a case such as: + ;; (let* ((fun (lambda (x) (+ x y))) (y 1)) (funcall fun 1)) + ;; A naive lambda-lifting would return + ;; (let* ((fun (lambda (y x) (+ x y))) (y 1)) (funcall fun y 1)) + ;; Where the external `y' is mistakenly captured by the inner one. + ;; So when we detect that case, we rewrite it to: + ;; (let* ((closed-y y) (fun (lambda (y x) (+ x y))) (y 1)) + ;; (funcall fun closed-y 1)) + ;; We do that even if there's no `funcall' that uses `fun' in the scope + ;; where `y' is shadowed by another variable because, to treat + ;; this case better, we'd need to traverse the tree one more time to + ;; collect this data, and I think that it's not worth it. + (mapcar (lambda (mapping) + (if (not (eq (cadr mapping) 'apply-partially)) + mapping + (cl-assert (eq (car mapping) (nth 2 mapping))) + `(,(car mapping) + apply-partially + ,(car mapping) + ,@(mapcar (lambda (arg) + (if (eq var arg) + closedsym arg)) + (nthcdr 3 mapping))))) + new-env)) + (defun cconv-convert (form env extend) ;; This function actually rewrites the tree. "Return FORM with all its lambdas changed so they are closed. @@ -299,9 +325,9 @@ places where they originally did not directly appear." (var (if (not (consp binder)) (prog1 binder (setq binder (list binder))) (when (cddr binder) - (byte-compile-log-warning - (format-message "Malformed `%S' binding: %S" - letsym binder))) + (byte-compile-warn + "Malformed `%S' binding: %S" + letsym binder)) (setq value (cadr binder)) (car binder))) (new-val @@ -350,34 +376,13 @@ places where they originally did not directly appear." (if (assq var new-env) (push `(,var) new-env)) (cconv-convert value env extend))))) - ;; The piece of code below letbinds free variables of a λ-lifted - ;; function if they are redefined in this let, example: - ;; (let* ((fun (lambda (x) (+ x y))) (y 1)) (funcall fun 1)) - ;; Here we can not pass y as parameter because it is redefined. - ;; So we add a (closed-y y) declaration. We do that even if the - ;; function is not used inside this let(*). The reason why we - ;; ignore this case is that we can't "look forward" to see if the - ;; function is called there or not. To treat this case better we'd - ;; need to traverse the tree one more time to collect this data, and - ;; I think that it's not worth it. - (when (memq var new-extend) - (let ((closedsym - (make-symbol (concat "closed-" (symbol-name var))))) - (setq new-env - (mapcar (lambda (mapping) - (if (not (eq (cadr mapping) 'apply-partially)) - mapping - (cl-assert (eq (car mapping) (nth 2 mapping))) - `(,(car mapping) - apply-partially - ,(car mapping) - ,@(mapcar (lambda (arg) - (if (eq var arg) - closedsym arg)) - (nthcdr 3 mapping))))) - new-env)) - (setq new-extend (remq var new-extend)) - (push closedsym new-extend) + (when (and (eq letsym 'let*) (memq var new-extend)) + ;; One of the lambda-lifted vars is shadowed, so add + ;; a reference to the outside binding and arrange to use + ;; that reference. + (let ((closedsym (make-symbol (format "closed-%s" var)))) + (setq new-env (cconv--remap-llv new-env var closedsym)) + (setq new-extend (cons closedsym (remq var new-extend))) (push `(,closedsym ,var) binders-new))) ;; We push the element after redefined free variables are @@ -390,6 +395,21 @@ places where they originally did not directly appear." (setq extend new-extend)) )) ; end of dolist over binders + (when (not (eq letsym 'let*)) + ;; We can't do the cconv--remap-llv at the same place for let and + ;; let* because in the case of `let', the shadowing may occur + ;; before we know that the var will be in `new-extend' (bug#24171). + (dolist (binder binders-new) + (when (memq (car-safe binder) new-extend) + ;; One of the lambda-lifted vars is shadowed, so add + ;; a reference to the outside binding and arrange to use + ;; that reference. + (let* ((var (car-safe binder)) + (closedsym (make-symbol (format "closed-%s" var)))) + (setq new-env (cconv--remap-llv new-env var closedsym)) + (setq new-extend (cons closedsym (remq var new-extend))) + (push `(,closedsym ,var) binders-new))))) + `(,letsym ,(nreverse binders-new) . ,(mapcar (lambda (form) (cconv-convert @@ -548,8 +568,8 @@ FORM is the parent form that binds this var." (`(,_ nil nil nil nil) nil) (`((,(and var (guard (eq ?_ (aref (symbol-name var) 0)))) . ,_) ,_ ,_ ,_ ,_) - (byte-compile-log-warning - (format-message "%s `%S' not left unused" varkind var)))) + (byte-compile-warn + "%s `%S' not left unused" varkind var))) (pcase vardata (`((,var . ,_) nil ,_ ,_ nil) ;; FIXME: This gives warnings in the wrong order, with imprecise line @@ -561,8 +581,8 @@ FORM is the parent form that binds this var." (eq ?_ (aref (symbol-name var) 0)) ;; As a special exception, ignore "ignore". (eq var 'ignored)) - (byte-compile-log-warning (format-message "Unused lexical %s `%S'" - varkind var)))) + (byte-compile-warn "Unused lexical %s `%S'" + varkind var))) ;; If it's unused, there's no point converting it into a cons-cell, even if ;; it's captured and mutated. (`(,binder ,_ t t ,_) @@ -586,9 +606,9 @@ FORM is the parent form that binds this var." (dolist (arg args) (cond ((byte-compile-not-lexical-var-p arg) - (byte-compile-log-warning - (format "Lexical argument shadows the dynamic variable %S" - arg))) + (byte-compile-warn + "Lexical argument shadows the dynamic variable %S" + arg)) ((eq ?& (aref (symbol-name arg) 0)) nil) ;Ignore &rest, &optional, ... (t (let ((varstruct (list arg nil nil nil nil))) (cl-pushnew arg byte-compile-lexical-variables) @@ -670,9 +690,8 @@ and updates the data stored in ENV." (setq forms (cddr forms)))) (`((lambda . ,_) . ,_) ; First element is lambda expression. - (byte-compile-log-warning - (format "Use of deprecated ((lambda %s ...) ...) form" (nth 1 (car form))) - t :warning) + (byte-compile-warn + "Use of deprecated ((lambda %s ...) ...) form" (nth 1 (car form))) (dolist (exp `((function ,(car form)) . ,(cdr form))) (cconv-analyze-form exp env))) @@ -681,8 +700,8 @@ and updates the data stored in ENV." (dolist (form forms) (cconv-analyze-form form env)))) ;; ((and `(quote ,v . ,_) (guard (assq v env))) - ;; (byte-compile-log-warning - ;; (format-message "Possible confusion variable/symbol for `%S'" v))) + ;; (byte-compile-warn + ;; "Possible confusion variable/symbol for `%S'" v)) (`(quote . ,_) nil) ; quote form (`(function . ,_) nil) ; same as quote @@ -699,8 +718,8 @@ and updates the data stored in ENV." (`(condition-case ,var ,protected-form . ,handlers) (cconv-analyze-form protected-form env) (when (and var (symbolp var) (byte-compile-not-lexical-var-p var)) - (byte-compile-log-warning - (format "Lexical variable shadows the dynamic variable %S" var))) + (byte-compile-warn + "Lexical variable shadows the dynamic variable %S" var)) (let* ((varstruct (list var nil nil nil nil))) (if var (push varstruct env)) (dolist (handler handlers) |