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| author | Alan Mackenzie <acm@muc.de> | 2022-02-05 10:43:27 +0000 |
|---|---|---|
| committer | Alan Mackenzie <acm@muc.de> | 2022-02-05 10:43:27 +0000 |
| commit | 9029212c869aa532e14d5e2048df070902d4ca8f (patch) | |
| tree | 1dc7d74d4a0f0b9dd3721b4c3d5196955241de6d /lisp/emacs-lisp/debug-early.el | |
| parent | 49192d14189a4abcf8f8e125adb8dab8c5064392 (diff) | |
| download | emacs-9029212c869aa532e14d5e2048df070902d4ca8f.tar.gz | |
* lisp/emacs-lisp/debug-early.el: Improve the documentation
Diffstat (limited to 'lisp/emacs-lisp/debug-early.el')
| -rw-r--r-- | lisp/emacs-lisp/debug-early.el | 28 |
1 files changed, 19 insertions, 9 deletions
diff --git a/lisp/emacs-lisp/debug-early.el b/lisp/emacs-lisp/debug-early.el index 718000bfa4c..e557643e467 100644 --- a/lisp/emacs-lisp/debug-early.el +++ b/lisp/emacs-lisp/debug-early.el @@ -24,10 +24,12 @@ ;;; Commentary: -;; This file dumps a backtrace on stderr when an error is thrown. -;; It has no dependencies on any Lisp libraries and is thus suitable -;; for generating backtraces in the early parts of bootstrapping. It -;; is also good for generating backtraces in batch mode in general. +;; This file dumps a backtrace on stderr when an error is thrown. It +;; has no dependencies on any Lisp libraries and is thus used for +;; generating backtraces for bugs in the early parts of bootstrapping. +;; It is also always used in batch model. It was introduced in Emacs +;; 29, before which there was no backtrace available during early +;; bootstrap. (defalias 'debug-early-backtrace #'(lambda () @@ -60,14 +62,22 @@ of the build process." (defalias 'debug-early #'(lambda (&rest args) - "Print a trace of Lisp function calls currently active. + "Print an error message with a backtrace of active Lisp function calls. The output stream used is the value of `standard-output'. -There should be two ARGS, the symbol `error' and a cons of -the error symbol and its data. +The Emacs core calls this function after an error has been +signaled, and supplies two ARGS. These are the symbol +`error' (which is ignored) and a cons of the error symbol and the +error data. + +`debug-early' is a simplified version of `debug', and is +available during the early parts of the build process. It is +superseded by `debug' after enough Lisp has been loaded to +support the latter, except in batch mode which always uses +`debug-early'. -This is a simplified version of `debug', intended for use -in debugging the early parts of the build process." +(In versions of Emacs prior to Emacs 29, no backtrace was +available before `debug' was usable.)" (princ "\nError: ") (prin1 (car (car (cdr args)))) ; The error symbol. (princ " ") |