GNU bug report logs - #79360
30.2; lldb shows incorrect code location when no column number is available

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: tracker <at> debbugs.gnu.org
Subject: bug#79360: closed (30.2; lldb shows incorrect code location when
 no column number is available)
Date: Sat, 06 Sep 2025 09:07:02 +0000

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Your message dated Sat, 06 Sep 2025 12:06:14 +0300
with message-id <86tt1geyrd.fsf <at> gnu.org>
and subject line Re: bug#79360: 30.2; lldb shows incorrect code location when no column number is available
has caused the debbugs.gnu.org bug report #79360,
regarding 30.2; lldb shows incorrect code location when no column number is available
to be marked as done.

(If you believe you have received this mail in error, please contact
help-debbugs <at> gnu.org.)


-- 
79360: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=79360
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From: Gustav Hållberg <gustav <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: 30.2;
 lldb shows incorrect code location when no column number is available
Date: Mon, 1 Sep 2025 16:42:33 +0200

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In (lldb), there is a bug that positions the source code location on the
last character of the previous line if lldb doesn't report a column number.

Example, save the following as "t.s" and compile (on x86-64) with "gcc -g
t.s -o t":

        .global _main
_main:
        xor %eax,%eax
        ret

and debug using (lldb "lldb ./t"):

(lldb) *b main*
  :
(lldb) *run*
  :
(lldb)
*disas*t`main:
    0x555555555129 <+0>: xorl   %eax, %eax
->  0x55555555512b <+2>: retq

but the source code location ends up at the last character of the "xor
%eax..." line.

Attaching proposed pach against 66ef930ebea4618c1dac71a09495766476ced1d6.

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[0001-lldb-bugfix-source-code-location-without-column.patch (application/octet-stream, attachment)]

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From: Eli Zaretskii <eliz <at> gnu.org>
To: Gustav Hållberg <gustav <at> gmail.com>
Cc: 79360-done <at> debbugs.gnu.org
Subject: Re: bug#79360: 30.2; lldb shows incorrect code location when no
 column number is available
Date: Sat, 06 Sep 2025 12:06:14 +0300

> From: Gustav Hållberg <gustav <at> gmail.com>
> Date: Mon, 1 Sep 2025 19:09:10 +0200
> Cc: 79360 <at> debbugs.gnu.org
> 
> It is a bug in the emacs M-x lldb command.
> 
> lldb (the tool) correctly sends an empty column field when it has no column number debug information.
> 
> If you look at the patch you'll see that the gud.el regexp (correctly) matches an empty digit sequence for the
> column number field, but that (incorrectly) is treated as column zero (which doesn't exist) rather than an
> absent column number field.

Thanks, I've now installed the change on the master branch, and I'm
therefore closing this bug.

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