[COMMIT] Be more careful still in #'cl-defsubst-expand.

APPROVE COMMIT NOTE: This patch has been committed. # HG changeset patch # User Aidan Kehoe <kehoea(a)parhasard.net&gt; # Date 1315753505 -3600 # Node ID 6c76f5b7e2e3e77d6a7c4a21507032a2adae439e # Parent d19b6e3bdf91e4e1f99857e9973c86fa2bebb40c Be more careful still in #'cl-defsubst-expand. lisp/ChangeLog addition: 2011-09-11 Aidan Kehoe <kehoea(a)parhasard.net&gt; * cl-macs.el (cl-defsubst-expand): Be more careful still here, make sure that any references to variables in BODY don't access those values in the enclosing scope when that would be inappropriate. Add some documentation of a potential reasonable approach to avoiding the problems with our (non-Common Lisp-conformant) #'symbol-macrolet. diff -r d19b6e3bdf91 -r 6c76f5b7e2e3 lisp/ChangeLog --- a/lisp/ChangeLog Sat Sep 10 13:17:29 2011 +0100 +++ b/lisp/ChangeLog Sun Sep 11 16:05:05 2011 +0100 ＠＠ -1,3 +1,13 ＠＠ +2011-09-11 Aidan Kehoe <kehoea(a)parhasard.net&gt; + + * cl-macs.el (cl-defsubst-expand): + Be more careful still here, make sure that any references to + variables in BODY don't access those values in the enclosing scope + when that would be inappropriate. + Add some documentation of a potential reasonable approach to + avoiding the problems with our (non-Common Lisp-conformant) + #'symbol-macrolet. + 2011-09-10 Aidan Kehoe <kehoea(a)parhasard.net&gt; * cl-macs.el (cl-defsubst-expand): diff -r d19b6e3bdf91 -r 6c76f5b7e2e3 lisp/cl-macs.el --- a/lisp/cl-macs.el Sat Sep 10 13:17:29 2011 +0100 +++ b/lisp/cl-macs.el Sun Sep 11 16:05:05 2011 +0100 ＠＠ -3238,18 +3238,25 ＠＠ (if (or simple (cl-const-expr-p argv)) (progn ;; Avoid infinite loop on symbol macro - ;; expansion, make sure none of the argvs - ;; refer to the symbols in the argns. + ;; expansion: (or (block find - ;; Can't use cl-expr-contains, that - ;; doesn't descend lambdas: - (subst nil argn argvs :test - #'(lambda (elt tree) + (subst nil argn argvs :test + #'(lambda (elt tree) + ;; Give nil if argn is + ;; in argvs somewhere: (if (eq elt tree) - (return-from find t)))) - nil) - (push (list argn argv) symbol-macros)) - (and unsafe (list (list argn argv)))) + (return-from find))))) + (let ((copy-symbol (copy-symbol argn))) + ;; Rename ARGN within BODY so it + ;; doesn't conflict with its value + ;; in the including scope: + (setq body + (cl-macroexpand-all + body `((,(eq-hash argn) + ,copy-symbol))) + argn copy-symbol))) + (push (list argn argv) symbol-macros) + (and unsafe (list (list argn argv)))) (list (list argn argv)))) argns argvs))) `(let ,lets ＠＠ -3260,6 +3267,13 ＠＠ ;; bound). We don't have GNU's issue where the replacement will ;; be done when the symbol is used in a function context, ;; because we're using #'symbol-macrolet instead of #'subst. + ;; + ;; #'symbol-macrolet as specified by Common Lisp is shadowed by + ;; #'let, #'let* and lambda argument lists, and that would suit + ;; our purposes here perfectly; we could implement it in + ;; cl-macroexpand-all by shadowing any existing symbol macros + ;; when we descend let forms or arglist lambdas. Doing it + ;; unconditionally could well break #'loop, though. ,symbol-macros ,body))))) -- ‘Iodine deficiency was endemic in parts of the UK until, through what has been described as “an unplanned and accidental public health triumph”, iodine was added to cattle feed to improve milk production in the 1930s.’ (EN Pearce, Lancet, June 2011) _______________________________________________ XEmacs-Patches mailing list XEmacs-Patches(a)xemacs.org http://lists.xemacs.org/mailman/listinfo/xemacs-patches