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bug#65622: Inappropriate suppression of backtrace on an error
From: |
Alan Mackenzie |
Subject: |
bug#65622: Inappropriate suppression of backtrace on an error |
Date: |
Wed, 30 Aug 2023 13:08:26 +0000 |
Hello, Emacs.
On a recent master branch Emacs:
(i) emacs -Q
(ii) Insert the following into *scratch*:
(defmacro hash-if (condition then-form &rest else-forms)
"A conditional compilation macro analogous to C's #if.
Evaluate CONDITION at macro-expansion time. If it is non-nil,
expand the macro to THEN-FORM. Otherwise expand it to ELSE-FORMS
enclosed in a `progn' form. ELSE-FORMS may be empty."
(declare (indent 2)
(debug (form sexp &rest sexp)))
(if (eval condition lexical-binding)
then-form
(cons 'progn else-forms)))
(defun foo (bar)
(hash-if (< emacs-major-version 19)
(car bar)
(cons bar bar)))
(iii) Evaluate hash-if by putting point after it and doing C-x C-e.
(iv) Attempt to instrument foo for edebug by putting point inside foo and
doing C-u C-M-x. This throws the error: "Ignoring macroexpansion
error: (void-function edebug-after)".
(v) Set debug-on-error to t with M-: (setq debug-on-error t).
(vi) Repeat (iv). This throws the same error, without a backtrace. This
lack of a backtrace is a bug.
(vii) This backtrace is almost certainly being suppressed by a frivolous
condition-case, whose main purpose appears to be making debugging more
difficult. ;-)
(viii) There would appear to be no justification for "ignoring" the error
(void-function edebug-after). Such error should not occur, and needs
debugging.
--
Alan Mackenzie (Nuremberg, Germany).
- bug#65622: Inappropriate suppression of backtrace on an error,
Alan Mackenzie <=