GNU bug report logs -
#13775
24.3.50; Omissions in documentation for crash reporting
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Reported by: Dmitry Gutov <dgutov <at> yandex.ru>
Date: Thu, 21 Feb 2013 07:29:01 UTC
Severity: minor
Found in version 24.3.50
Done: Dmitry Gutov <dgutov <at> yandex.ru>
Bug is archived. No further changes may be made.
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Your bug report
#13775: 24.3.50; Omissions in documentation for crash reporting
which was filed against the emacs package, has been closed.
The explanation is attached below, along with your original report.
If you require more details, please reply to 13775 <at> debbugs.gnu.org.
--
13775: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=13775
GNU Bug Tracking System
Contact help-debbugs <at> gnu.org with problems
[Message part 2 (message/rfc822, inline)]
On 22.02.2013 13:24, Eli Zaretskii wrote:
> I meant both the switches of configure and the compiler/linker
> switches and options.
>
>> The ./configure --help output tells how to override switches in general,
>> my complaint is about insufficient detail. Is the "Some influential
>> environment variables" part provided by autoconf or somesuch?
>
> I don't understand the question. The relevant part of the help text
You answered it below, "this is a standard text shown by ...".
> is this:
>
> Some influential environment variables:
> CC C compiler command
> CFLAGS C compiler flags
> LDFLAGS linker flags, e.g. -L<lib dir> if you have libraries in a
> nonstandard directory <lib dir>
> LIBS libraries to pass to the linker, e.g. -l<library>
> CPPFLAGS (Objective) C/C++ preprocessor flags, e.g. -I<include dir> if
> you have headers in a nonstandard directory <include dir>
> CPP C preprocessor
> XMKMF Path to xmkmf, Makefile generator for X Window System
>
> Use these variables to override the choices made by `configure' or to help
> it to find libraries and programs with nonstandard names/locations.
>
> Which part(s) of this are unclear?
>
> In any case, this is a standard text shown by every configure script
> out there, so if you think it should be clarified, please complain to
> the Autoconf developers.
Thanks, maybe I'll do that, sometime.
>>>> 1. Calling `xbacktrace' requires src/.gdbinit to be loaded. It
>>>> a) requires the user to run gdb exactly from src/ (not `gdb src/emacs'),
>>>
>>> The file etc/DEBUG tells you that at the beginning:
>>>
>>> ** When you debug Emacs with GDB, you should start it in the directory
>>> where the executable was made. That directory has a .gdbinit file
>>> that defines various "user-defined" commands for debugging Emacs.
>>> (These commands are described below under "Examining Lisp object
>>> values" and "Debugging Emacs Redisplay problems".)
>>
>> Um, yes, I read that. Maybe I should've skipped this part of the
>> complaint. But is this exact wording ("the directory where the
>> executable was made") important? If it just said "./src", that would be
>> more obvious.
>
> I added that (revision 111290 on the emacs-24 branch).
>
>>>> b) requires them to modify the `auto-load safe-path', or that .gdbinit
>>>> is ignored.
>>>
>>> This "feature" entered GDB only recently. Versions of GDB before 7.5
>>> don't need that, and will barf if you use this command. I don't see
>>> any reasonable way of dealing with this without confusing newbies even
>>> more (while veteran GDB users already know how to negotiate this
>>> obstacle).
>>
>> If the feature isn't considered for removal, this argument will become
>> less and less important over time. And the odds of a newbie being
>> confused by safe-path will approach 100%.
>
> But GDB already tells you how to allow .gdbinit to be auto-loaded, and
> also points to the GDB manual. If the text displayed by GDB is not
> clear or confusing, I suggest to report that to GDB maintainers.
>
>> I'm not specifically asking to list the exact commands or ~/.gdbinit
>> contents to work around safe-path. Maybe just mention the feature and,
>> optionally, suggest consulting GDB manual, if that isn't obvious
>> already?
>
> I added that to etc/DEBUG.
>
>> But specifying exactly what to do if GDB version is >= 7.5
>> would also work.
>
> That's hard to do, because the solution depends on the end-user's
> preferences regarding security and on the degree of their machine's
> exposure to other users and to the outside world. The GDB manual
> discusses the possible solutions, so a pointer to it will allow the
> user to make up her mind.
>
>>>> a) Do I set the variable when calling `make', or do I have to re-run
>>>> ./configure? Not obvious, the answer is "the latter".
>>>
>>> Actually, both will work.
>>
>> Not exactly.
>>
>> 'CFLAGS="-g3" ./configure' works.
>> 'CFLAGS="-g3" make' doesn't.
>>
>> 'make CFLAGS="-g3"' does work, but AFAIK that's not the usual way of
>> binding an environment variable value.
>
> CFLAGS is a Make variable. Make normally initializes all its
> variables by looking at the environment. But 'CFLAGS="-g3" make'
> doesn't export the value of CFLAGS for Make to see it, it only inserts
> CFLAGS into the shell's own environment. That is why the command
> 'CFLAGS="-g3" make' doesn't work, while 'make CFLAGS="-g3"' does.
I see, I think.
> This is all standard shell and Make stuff, I don't think it's
> reasonable to expect Emacs documentation to teach all that.
>
>> I think "compile without optimizations" or "compile for debugging" is a
>> sufficiently common special case to warrant listing the recommended
>> command somewhere in etc/DEBUG. That will take a few lines at the most.
>
> It's already there, it just didn't mention the -O0 option explicitly;
> I added that. (Again, this is a basic compiler option, not something
> specific to Emacs.)
Like I described, my difficulty here was that using "-O0" by itself is
not enough, without "-g3" the resulting build is even less debuggable.
Omitting "-O0", leaving just "-g3", works, on the other hand, because
the optimization is enabled by default due to the default CFLAGS value
(AFAICT).
Anyway, you've addressed that in 111290, as well as two other items.
Thank you, I'm considering this issue fixed.
[Message part 3 (message/rfc822, inline)]
As a non-GDB-wielding user with not much C experience, I had a hard time
following the instructions in `report-emacs-bug' and the ones that
followed.
1. Calling `xbacktrace' requires src/.gdbinit to be loaded. It
a) requires the user to run gdb exactly from src/ (not `gdb src/emacs'),
b) requires them to modify the `auto-load safe-path', or that .gdbinit
is ignored.
2. "Compile without optimizations" - how do I do that? `configure
--help' doesn't seem to show any pertinent options. ...but wait, it says
I can override the choices made by the script.
a) Do I set the variable when calling `make', or do I have to re-run
./configure? Not obvious, the answer is "the latter".
b) I don't know the choice the script made, how do I not break
anything by overriding it? My first choice was "-O0", and that resulted
in an unoptimized build with no debugging symbols (I think).
3. In #13749 (which caused me to write this), Paul also suggests using
-DENABLE_CHECKING. If I'm not mistaken, this variable isn't documented
anywhere.
This bug report was last modified 12 years and 154 days ago.
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