Re: [PATCH v2] gdb/configure.ac: Add option --with-additional-debug-dirs

[Thiago Jung Bauermann <thiago.bauermann@linaro.org>]

Eli Zaretskii <eliz@gnu.org> writes:

>> Cc: Tom Tromey <tom@tromey.com>
>> Date: Wed,  4 Oct 2023 15:31:02 -0300
>> From: Thiago Jung Bauermann via Gdb-patches <gdb-patches@sourceware.org>
>> 
>> If you want to install GDB in a custom prefix, have it look for debug info
>> in that prefix but also in the distro's default location (typically,
>> /usr/lib/debug) and run the GDB testsuite before doing "make install", you
>> have a bit of a problem:
>> 
>> Configuring GDB with '--prefix=$PREFIX' sets the GDB 'debug-file-directory'
>> parameter to $PREFIX/lib/debug.  Unfortunately this precludes GDB from
>> looking for distro-installed debug info in /usr/lib/debug.  For regular GDB
>> use you could set debug-file-directory to $PREFIX:/usr/lib/debug in
>> $PREFIX/etc/gdbinit so that GDB will look in both places, but if you want
>> to run the testsuite then that doesn't help because in that case GDB runs
>> with the '-nx' option.
>> 
>> There's the configure option '--with-separate-debug-dir' to set the default
>> value for 'debug-file-directory', but it accepts only one directory and not
>> a list.  I considered modifying it to accept a list, but it's not obvious
>> how to do that because its value is also used by BFD, as well as processed
>> for "relocatability".
>> 
>> I thought it was simpler to add a new option to specify a list of
>> additional directories that will be appended to the debug-file-directory
>> setting.
>
> Thanks, the documentation parts are okay.

Thank you!

> However, I wonder: on MS-Windows, the "colon-separated list" becomes
> "semi-colon separated list", and I have an old and annoying problem
> with 2 similar configure-time options, --with-auto-load-safe-path= and
> --with-auto-load-dir=, which fail to communicate semi-colon separated
> lists to gdb/configure, and require me to manually edit gdb/config.h
> and rebuild.  So I wonder whether this new option will have the same
> problem, and whether we could perhaps take this opportunity for fixing
> this?
>
> This is https://sourceware.org/bugzilla/show_bug.cgi?id=18898, btw.

I looked a bit into this, and I don't see an easy solution. The problem
is that shell scripting language is notoriously bad at keeping data from
leaking into the code.

If I do:

$ ~/src/binutils-gdb/configure \
    --disable-{binutils,ld,gold,gas,sim,gprof,gprofng} \
    --with-auto-load-dir='foo;bar' && make

I get:

checking for default auto-load directory... /home/bauermann/src/binutils-gdb/gdb/configure: line 18004: bar: command not found
foo;bar
checking for default auto-load safe-path... /home/bauermann/src/binutils-gdb/gdb/configure: line 18031: bar: command not found
foo;bar

Line 18004 is:

ac_define_dir=`eval echo $escape_dir`

Line 18031 is identical.

If the configure script could use bash features instead of having to
assume a POSIX shell, we could use "printf %q" to escape the input. Is
there an equivalent solution that's in POSIX shell?

In any case, any solution would be in an autoconf macro, not in GDB.

As a workaround, I was able to get away with some escaping:

$ ~/src/binutils-gdb/configure \
    --disable-{binutils,ld,gold,gas,sim,gprof,gprofng} \
    --with-auto-load-dir='foo\\\;bar\\\;baz' && make
    ⋮
checking for default auto-load directory... foo\\\;bar\\\;baz
checking for default auto-load safe-path... foo\\\;bar\\\;baz
    ⋮
$ grep AUTO_LOAD gdb/config.h
#define AUTO_LOAD_DIR "foo;bar;baz"
#define AUTO_LOAD_SAFE_PATH "foo;bar;baz"


> Reviewed-By: Eli Zaretskii <eliz@gnu.org>


-- 
Thiago