From 45252ad8f932c98a373ef0ab7f3363a3e27ccbe4 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Mattias=20Engdeg=C3=A5rd?= Date: Mon, 22 Nov 2021 16:56:38 +0100 Subject: [PATCH] Fix closure-conversion of shadowed captured lambda-lifted vars Lambda-lifted variables (ones passed explicitly to lambda-lifted functions) that are also captured in an outer closure and shadowed were renamed incorrectly (bug#51982). Reported by Paul Pogonyshev. * lisp/emacs-lisp/cconv.el (cconv--lifted-arg): New. (cconv-convert): Provide correct definiens for the closed-over variable. * test/lisp/emacs-lisp/bytecomp-tests.el (bytecomp-tests--test-cases): * test/lisp/emacs-lisp/cconv-tests.el (cconv-tests--intern-all) (cconv-closure-convert-remap-var): Add tests. --- lisp/emacs-lisp/cconv.el | 31 ++++- test/lisp/emacs-lisp/bytecomp-tests.el | 43 +++++++ test/lisp/emacs-lisp/cconv-tests.el | 152 +++++++++++++++++++++++++ 3 files changed, 220 insertions(+), 6 deletions(-) diff --git a/lisp/emacs-lisp/cconv.el b/lisp/emacs-lisp/cconv.el index 03e109f2508..f86744fd1ae 100644 --- a/lisp/emacs-lisp/cconv.el +++ b/lisp/emacs-lisp/cconv.el @@ -304,6 +304,25 @@ of converted forms." `(,@(nreverse special-forms) ,@(macroexp-unprogn body)))) funcbody))) +(defun cconv--lifted-arg (var env) + "The argument to use for VAR in λ-lifted calls according to ENV. +This is used when VAR is being shadowed; we may still need its value for +such calls." + (let ((mapping (cdr (assq var env)))) + (pcase-exhaustive mapping + (`(internal-get-closed-var . ,_) + ;; The variable is captured. + mapping) + (`(car-safe (internal-get-closed-var . ,_)) + ;; The variable is mutably captured; skip + ;; the indirection step because the variable is + ;; passed "by reference" to the λ-lifted function. + (cadr mapping)) + ((or '() `(car-safe ,(pred symbolp))) + ;; The variable is not captured; use the (shadowed) variable value. + ;; (If the mapping is `(car-safe SYMBOL)', SYMBOL is always VAR. + var)))) + (defun cconv-convert (form env extend) ;; This function actually rewrites the tree. "Return FORM with all its lambdas changed so they are closed. @@ -428,10 +447,11 @@ places where they originally did not directly appear." ;; 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)))) + (let ((var-def (cconv--lifted-arg var env)) + (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))) + (push `(,closedsym ,var-def) binders-new))) ;; We push the element after redefined free variables are ;; processed. This is important to avoid the bug when free @@ -449,14 +469,13 @@ places where they originally did not directly appear." ;; 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. + ;; One of the lambda-lifted vars is shadowed. (let* ((var (car-safe binder)) + (var-def (cconv--lifted-arg var env)) (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))))) + (push `(,closedsym ,var-def) binders-new))))) `(,letsym ,(nreverse binders-new) . ,(mapcar (lambda (form) diff --git a/test/lisp/emacs-lisp/bytecomp-tests.el b/test/lisp/emacs-lisp/bytecomp-tests.el index 816f14a18d5..b82afd353cf 100644 --- a/test/lisp/emacs-lisp/bytecomp-tests.el +++ b/test/lisp/emacs-lisp/bytecomp-tests.el @@ -643,6 +643,49 @@ inner loops respectively." (cond) (mapcar (lambda (x) (cond ((= x 0)))) '(0 1)) + + ;; These expressions give different results in lexbind and dynbind modes, + ;; but in each the compiler and interpreter should agree! + ;; (They look much the same but come in pairs exercising both the + ;; `let' and `let*' paths.) + (let ((f (lambda (x) + (lambda () + (let ((g (lambda () x))) + (let ((x 'a)) + (list x (funcall g)))))))) + (funcall (funcall f 'b))) + (let ((f (lambda (x) + (lambda () + (let ((g (lambda () x))) + (let* ((x 'a)) + (list x (funcall g)))))))) + (funcall (funcall f 'b))) + (let ((f (lambda (x) + (lambda () + (let ((g (lambda () x))) + (setq x (list x x)) + (let ((x 'a)) + (list x (funcall g)))))))) + (funcall (funcall f 'b))) + (let ((f (lambda (x) + (lambda () + (let ((g (lambda () x))) + (setq x (list x x)) + (let* ((x 'a)) + (list x (funcall g)))))))) + (funcall (funcall f 'b))) + (let ((f (lambda (x) + (let ((g (lambda () x)) + (h (lambda () (setq x (list x x))))) + (let ((x 'a)) + (list x (funcall g) (funcall h))))))) + (funcall (funcall f 'b))) + (let ((f (lambda (x) + (let ((g (lambda () x)) + (h (lambda () (setq x (list x x))))) + (let* ((x 'a)) + (list x (funcall g) (funcall h))))))) + (funcall (funcall f 'b))) ) "List of expressions for cross-testing interpreted and compiled code.") diff --git a/test/lisp/emacs-lisp/cconv-tests.el b/test/lisp/emacs-lisp/cconv-tests.el index 4290571735e..0701892b8c4 100644 --- a/test/lisp/emacs-lisp/cconv-tests.el +++ b/test/lisp/emacs-lisp/cconv-tests.el @@ -205,5 +205,157 @@ nil 99) 42))) +(defun cconv-tests--intern-all (x) + "Intern all symbols in X." + (cond ((symbolp x) (intern (symbol-name x))) + ((consp x) (cons (cconv-tests--intern-all (car x)) + (cconv-tests--intern-all (cdr x)))) + ;; Assume we don't need to deal with vectors etc. + (t x))) + +(ert-deftest cconv-closure-convert-remap-var () + ;; Verify that we correctly remap shadowed lambda-lifted variables. + + ;; We intern all symbols for ease of comparison; this works because + ;; the `cconv-closure-convert' result should contain no pair of + ;; distinct symbols having the same name. + + ;; Sanity check: captured variable, no lambda-lifting or shadowing: + (should (equal (cconv-tests--intern-all + (cconv-closure-convert + '#'(lambda (x) + #'(lambda () x)))) + '#'(lambda (x) + (internal-make-closure + nil (x) nil + (internal-get-closed-var 0))))) + + ;; Basic case: + (should (equal (cconv-tests--intern-all + (cconv-closure-convert + '#'(lambda (x) + (let ((f #'(lambda () x))) + (let ((x 'b)) + (list x (funcall f))))))) + '#'(lambda (x) + (let ((f #'(lambda (x) x))) + (let ((x 'b) + (closed-x x)) + (list x (funcall f closed-x))))))) + (should (equal (cconv-tests--intern-all + (cconv-closure-convert + '#'(lambda (x) + (let ((f #'(lambda () x))) + (let* ((x 'b)) + (list x (funcall f))))))) + '#'(lambda (x) + (let ((f #'(lambda (x) x))) + (let* ((closed-x x) + (x 'b)) + (list x (funcall f closed-x))))))) + + ;; With the lambda-lifted shadowed variable also being captured: + (should (equal + (cconv-tests--intern-all + (cconv-closure-convert + '#'(lambda (x) + #'(lambda () + (let ((f #'(lambda () x))) + (let ((x 'a)) + (list x (funcall f)))))))) + '#'(lambda (x) + (internal-make-closure + nil (x) nil + (let ((f #'(lambda (x) x))) + (let ((x 'a) + (closed-x (internal-get-closed-var 0))) + (list x (funcall f closed-x)))))))) + (should (equal + (cconv-tests--intern-all + (cconv-closure-convert + '#'(lambda (x) + #'(lambda () + (let ((f #'(lambda () x))) + (let* ((x 'a)) + (list x (funcall f)))))))) + '#'(lambda (x) + (internal-make-closure + nil (x) nil + (let ((f #'(lambda (x) x))) + (let* ((closed-x (internal-get-closed-var 0)) + (x 'a)) + (list x (funcall f closed-x)))))))) + ;; With lambda-lifted shadowed variable also being mutably captured: + (should (equal + (cconv-tests--intern-all + (cconv-closure-convert + '#'(lambda (x) + #'(lambda () + (let ((f #'(lambda () x))) + (setq x x) + (let ((x 'a)) + (list x (funcall f)))))))) + '#'(lambda (x) + (let ((x (list x))) + (internal-make-closure + nil (x) nil + (let ((f #'(lambda (x) (car-safe x)))) + (setcar (internal-get-closed-var 0) + (car-safe (internal-get-closed-var 0))) + (let ((x 'a) + (closed-x (internal-get-closed-var 0))) + (list x (funcall f closed-x))))))))) + (should (equal + (cconv-tests--intern-all + (cconv-closure-convert + '#'(lambda (x) + #'(lambda () + (let ((f #'(lambda () x))) + (setq x x) + (let* ((x 'a)) + (list x (funcall f)))))))) + '#'(lambda (x) + (let ((x (list x))) + (internal-make-closure + nil (x) nil + (let ((f #'(lambda (x) (car-safe x)))) + (setcar (internal-get-closed-var 0) + (car-safe (internal-get-closed-var 0))) + (let* ((closed-x (internal-get-closed-var 0)) + (x 'a)) + (list x (funcall f closed-x))))))))) + ;; Lambda-lifted variable that isn't actually captured where it is shadowed: + (should (equal + (cconv-tests--intern-all + (cconv-closure-convert + '#'(lambda (x) + (let ((g #'(lambda () x)) + (h #'(lambda () (setq x x)))) + (let ((x 'b)) + (list x (funcall g) (funcall h))))))) + '#'(lambda (x) + (let ((x (list x))) + (let ((g #'(lambda (x) (car-safe x))) + (h #'(lambda (x) (setcar x (car-safe x))))) + (let ((x 'b) + (closed-x x)) + (list x (funcall g closed-x) (funcall h closed-x)))))))) + (should (equal + (cconv-tests--intern-all + (cconv-closure-convert + '#'(lambda (x) + (let ((g #'(lambda () x)) + (h #'(lambda () (setq x x)))) + (let* ((x 'b)) + (list x (funcall g) (funcall h))))))) + '#'(lambda (x) + (let ((x (list x))) + (let ((g #'(lambda (x) (car-safe x))) + (h #'(lambda (x) (setcar x (car-safe x))))) + (let* ((closed-x x) + (x 'b)) + (list x (funcall g closed-x) (funcall h closed-x)))))))) + ) + (provide 'cconv-tests) ;;; cconv-tests.el ends here -- 2.39.2