diff options
Diffstat (limited to 'lisp/emacs-lisp/macroexp.el')
| -rw-r--r-- | lisp/emacs-lisp/macroexp.el | 110 |
1 files changed, 102 insertions, 8 deletions
diff --git a/lisp/emacs-lisp/macroexp.el b/lisp/emacs-lisp/macroexp.el index 70eab149837..394225d697e 100644 --- a/lisp/emacs-lisp/macroexp.el +++ b/lisp/emacs-lisp/macroexp.el @@ -100,6 +100,17 @@ each clause." (error (message "Compiler-macro error for %S: %S" (car form) err) form))) +(defun macroexp--eval-if-compile (&rest _forms) + "Pseudo function used internally by macroexp to delay warnings. +The purpose is to delay warnings to bytecomp.el, so they can use things +like `byte-compile-log-warning' to get better file-and-line-number data +and also to avoid outputting the warning during normal execution." + nil) +(put 'macroexp--eval-if-compile 'byte-compile + (lambda (form) + (mapc (lambda (x) (funcall (eval x))) (cdr form)) + (byte-compile-constant nil))) + (defun macroexp--expand-all (form) "Expand all macros in FORM. This is an internal version of `macroexpand-all'. @@ -112,14 +123,17 @@ Assumes the caller has bound `macroexpand-all-environment'." (macroexpand (macroexp--all-forms form 1) macroexpand-all-environment) ;; Normal form; get its expansion, and then expand arguments. - (let ((new-form (macroexpand form macroexpand-all-environment))) - (when (and (not (eq form new-form)) ;It was a macro call. - (car-safe form) - (symbolp (car form)) - (get (car form) 'byte-obsolete-info) - (fboundp 'byte-compile-warn-obsolete)) - (byte-compile-warn-obsolete (car form))) - (setq form new-form)) + (let ((new-form + (macroexpand form macroexpand-all-environment))) + (setq form + (if (and (not (eq form new-form)) ;It was a macro call. + (car-safe form) + (symbolp (car form)) + (get (car form) 'byte-obsolete-info)) + `(progn (macroexp--eval-if-compile + (lambda () (byte-compile-warn-obsolete ',(car form)))) + ,new-form) + new-form))) (pcase form (`(cond . ,clauses) (macroexp--cons 'cond (macroexp--all-clauses clauses) form)) @@ -323,6 +337,86 @@ symbol itself." "Return non-nil if EXP can be copied without extra cost." (or (symbolp exp) (macroexp-const-p exp))) +;;; Load-time macro-expansion. + +;; Because macro-expansion used to be more lazy, eager macro-expansion +;; tends to bump into previously harmless/unnoticeable cyclic-dependencies. +;; So, we have to delay macro-expansion like we used to when we detect +;; such a cycle, and we also want to help coders resolve those cycles (since +;; they can be non-obvious) by providing a usefully trimmed backtrace +;; (hopefully) highlighting the problem. + +(defun macroexp--backtrace () + "Return the Elisp backtrace, more recent frames first." + (let ((bt ()) + (i 0)) + (while + (let ((frame (backtrace-frame i))) + (when frame + (push frame bt) + (setq i (1+ i))))) + (nreverse bt))) + +(defun macroexp--trim-backtrace-frame (frame) + (pcase frame + (`(,_ macroexpand (,head . ,_) . ,_) `(macroexpand (,head …))) + (`(,_ internal-macroexpand-for-load (,head ,second . ,_) . ,_) + (if (or (symbolp second) + (and (eq 'quote (car-safe second)) + (symbolp (cadr second)))) + `(macroexpand-all (,head ,second …)) + '(macroexpand-all …))) + (`(,_ load-with-code-conversion ,name . ,_) + `(load ,(file-name-nondirectory name))))) + +(defvar macroexp--pending-eager-loads nil + "Stack of files currently undergoing eager macro-expansion.") + +(defun internal-macroexpand-for-load (form) + ;; Called from the eager-macroexpansion in readevalloop. + (cond + ;; Don't repeat the same warning for every top-level element. + ((eq 'skip (car macroexp--pending-eager-loads)) form) + ;; If we detect a cycle, skip macro-expansion for now, and output a warning + ;; with a trimmed backtrace. + ((and load-file-name (member load-file-name macroexp--pending-eager-loads)) + (let* ((bt (delq nil + (mapcar #'macroexp--trim-backtrace-frame + (macroexp--backtrace)))) + (elem `(load ,(file-name-nondirectory load-file-name))) + (tail (member elem (cdr (member elem bt))))) + (if tail (setcdr tail (list '…))) + (if (eq (car-safe (car bt)) 'macroexpand-all) (setq bt (cdr bt))) + (message "Warning: Eager macro-expansion skipped due to cycle:\n %s" + (mapconcat #'prin1-to-string (nreverse bt) " => ")) + (push 'skip macroexp--pending-eager-loads) + form)) + (t + (condition-case err + (let ((macroexp--pending-eager-loads + (cons load-file-name macroexp--pending-eager-loads))) + (macroexpand-all form)) + (error + ;; Hopefully this shouldn't happen thanks to the cycle detection, + ;; but in case it does happen, let's catch the error and give the + ;; code a chance to macro-expand later. + (message "Eager macro-expansion failure: %S" err) + form))))) + +;; ¡¡¡ Big Ugly Hack !!! +;; src/bootstrap-emacs is mostly used to compile .el files, so it needs +;; macroexp, bytecomp, cconv, and byte-opt to be fast. Generally this is done +;; by compiling those files first, but this only makes a difference if those +;; files are not preloaded. But macroexp.el is preloaded so we reload it if +;; the current version is interpreted and there's a compiled version available. +(eval-when-compile + (add-hook 'emacs-startup-hook + (lambda () + (and (not (byte-code-function-p + (symbol-function 'macroexpand-all))) + (locate-library "macroexp.elc") + (load "macroexp.elc"))))) + (provide 'macroexp) ;;; macroexp.el ends here |