From: Noam Postavsky <npostavs@gmail.com>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: Michael Heerdegen <michael_heerdegen@web.de>,
Joost Kremers <joostkremers@fastmail.fm>,
40088@debbugs.gnu.org
Subject: bug#40088: 27.0.90; Symbol’s value as variable is void: debugger-outer-match-data
Date: Fri, 20 Mar 2020 04:37:49 -0400 [thread overview]
Message-ID: <87d097l8v6.fsf@gmail.com> (raw)
In-Reply-To: <jwvblotmc8k.fsf-monnier+emacs@gnu.org> (Stefan Monnier's message of "Wed, 18 Mar 2020 20:18:50 -0400")
[-- Attachment #1: Type: text/plain, Size: 1007 bytes --]
tags 40088 + patch
quit
Stefan Monnier <monnier@iro.umontreal.ca> writes:
>> Since the void-variable is getting triggered from
>> backtrace_eval_unrewind, I tried the patch below, which almost seems
>> to fix the problem,
>
> Indeed, the patch looks good (except for the removal of `static` which
> seems like a spurious artifact).
No, the removal is on purpose, because I'm calling default_value from
eval.c, and it's defined in data.c. But, maybe you thought that because
I didn't add the corresponding declaration in a header file, and...
>> but after continuing from the debugger there's a
>> segfault in GC, so it's definitely not the Right Thing.
... the segfault happens because I forgot to declare default_value in
lisp.h, so its return value got converted to int. *Forehead slap*
So here's the proper patch. Eli, is it okay for emacs-27? As I
mentioned earlier, the underlying bug was present in Emacs 26 and
earlier, but it's only surfaced in Emacs 27 because of debug.el
enhancements.
[-- Attachment #2: patch --]
[-- Type: text/plain, Size: 2139 bytes --]
From 9afae526cf1959f5922dffb9254578dfe12ee4be Mon Sep 17 00:00:00 2001
From: Noam Postavsky <npostavs@gmail.com>
Date: Fri, 20 Mar 2020 04:07:39 -0400
Subject: [PATCH] Don't signal during backtrace unrewind (Bug#40088)
* src/data.c (default_value): Make non-static.
* src/lisp.h: Declare it.
* src/eval.c (backtrace_eval_unrewind): Call default_value and
buffer_local_value instead of Fdefault_value and Fbuffer_local_value,
respectively, so that unrewinding to unbound variables will not signal
an error.
---
src/data.c | 2 +-
src/eval.c | 4 ++--
src/lisp.h | 1 +
3 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/src/data.c b/src/data.c
index b153068846..5ce5e360ab 100644
--- a/src/data.c
+++ b/src/data.c
@@ -1573,7 +1573,7 @@ notify_variable_watchers (Lisp_Object symbol,
/* Return the default value of SYMBOL, but don't check for voidness.
Return Qunbound if it is void. */
-static Lisp_Object
+Lisp_Object
default_value (Lisp_Object symbol)
{
struct Lisp_Symbol *sym;
diff --git a/src/eval.c b/src/eval.c
index 4559a0e1f6..78a787c4ff 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -3816,7 +3816,7 @@ backtrace_eval_unrewind (int distance)
{
Lisp_Object sym = specpdl_symbol (tmp);
Lisp_Object old_value = specpdl_old_value (tmp);
- set_specpdl_old_value (tmp, Fdefault_value (sym));
+ set_specpdl_old_value (tmp, default_value (sym));
Fset_default (sym, old_value);
}
break;
@@ -3832,7 +3832,7 @@ backtrace_eval_unrewind (int distance)
if (!NILP (Flocal_variable_p (symbol, where)))
{
set_specpdl_old_value
- (tmp, Fbuffer_local_value (symbol, where));
+ (tmp, buffer_local_value (symbol, where));
set_internal (symbol, old_value, where, SET_INTERNAL_UNBIND);
}
}
diff --git a/src/lisp.h b/src/lisp.h
index 8674fe11a6..92294ac1d3 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -594,6 +594,7 @@ #define ENUM_BF(TYPE) enum TYPE
/* Defined in data.c. */
extern AVOID wrong_type_argument (Lisp_Object, Lisp_Object);
+extern Lisp_Object default_value (Lisp_Object symbol);
/* Defined in emacs.c. */
--
2.11.0
next prev parent reply other threads:[~2020-03-20 8:37 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-16 11:40 bug#40088: 27.0.90; Symbol’s value as variable is void: debugger-outer-match-data Joost Kremers
2020-03-17 1:01 ` Michael Heerdegen
2020-03-17 10:41 ` Robert Pluim
2020-03-17 11:06 ` Dmitry Gutov
2020-03-18 0:06 ` Michael Heerdegen
2020-03-18 0:12 ` bug#40088: 27.0.90; Symbol?s " Drew Adams
2020-03-18 1:44 ` Noam Postavsky
2020-03-18 1:49 ` Drew Adams
2020-03-18 22:31 ` Michael Heerdegen
2020-03-18 6:34 ` bug#40088: 27.0.90; Symbol’s " Dmitry Gutov
2020-03-18 22:24 ` Michael Heerdegen
2020-03-18 22:30 ` Dmitry Gutov
2020-03-18 22:46 ` Michael Heerdegen
2020-03-17 11:44 ` Noam Postavsky
2020-03-19 0:04 ` Noam Postavsky
2020-03-19 0:18 ` Stefan Monnier
2020-03-20 8:37 ` Noam Postavsky [this message]
2020-03-20 8:56 ` Eli Zaretskii
2020-03-21 23:47 ` Noam Postavsky
2020-03-22 14:25 ` Eli Zaretskii
2020-03-23 3:17 ` Noam Postavsky
2020-03-23 3:30 ` Eli Zaretskii
2020-03-23 3:40 ` Noam Postavsky
2020-03-23 14:16 ` Eli Zaretskii
2020-03-23 14:34 ` Noam Postavsky
2020-03-23 15:53 ` Joost Kremers
2020-03-20 13:20 ` Stefan Monnier
2020-03-20 14:00 ` Robert Pluim
2020-03-20 14:51 ` Stefan Monnier
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