[PATCH] XDM: Fix FTBFS with gold or recent gcc releases.

[Fernando Lemos]

On Sat, Feb 19, 2011 at 5:36 PM, Alan Coopersmith
<alan.coopersmith at oracle.com> wrote:
[...]
> On 02/19/11 09:21 AM, Mikhail Gusarov wrote:
>>
>> Twas brillig at 09:19:24 19.02.2011 UTC-08 when
>> alan.coopersmith at oracle.com did gyre and gimble:
>>
>>  AC> Neither of those explain what "FTBFS" means.
>>
>> "fails to build from source". First result of google://FTBFS gives you
>> this answer, by the way.
>
> Yes, I'd seen that, but people shouldn't have to google to understand a
> commit message, and that abbreviation could simply be replaced by the
> word "build" and be just as accurate and more understandable without using
> any more characters.   (In our source trees, the only possible build is a
> build from source.)
[...]

Sorry, I thought the term was well known. Yes, it means "fails to
build from source".

The master branch of XDM doesn't build anymore in Debian wheezy/sid
(and I assume some other distros as well) because of the
aforementioned DSO linking changes.

[...]
>> +
>> +# Function dl() comes from the C library or -ldl
>> +AC_SEARCH_LIBS([dlopen], [dl])
>
>This seems to duplicate the checks we already have via AC_LIBTOOL_DLOPEN.
>Those only went into git a couple months ago, and haven't been released
>yet:
>http://cgit.freedesktop.org/xorg/app/xdm/commit/?id=50c96170ad42321310c346cf412f9ae7e80ec2a7
[...]

I'm using the master branch (currently edd8d362), which contains this
commit. It looks like AC_LIBTOOL_DLOPEN doesn't automatically add -dl.

[...]
>>  # Checks for header files.
>> @@ -287,7 +290,7 @@ AC_SUBST(SHELL_CMD)
>>
>>  # Checks for pkg-config packages
>>
>> -PKG_CHECK_MODULES(XDM, xmu x11 xau)
>> +PKG_CHECK_MODULES(XDM, xmu x11 xau xext)
>
>Why do you believe this is needed?   I see nothing in xdm that calls
>functions in libXext.   The greeter library does, but that's already
>covered in:
>PKG_CHECK_MODULES(XDMGREET, xt x11 xext)
[...]

You're absolutely right, it must have been a leftover from earlier
troubleshooting. I reverted that change and realized it isn't
necessary. Please ignore that hunk.

[...]
> What error are you getting that this solves?
[...]

/usr/bin/ld: session.o: undefined reference to symbol 'dlclose@@GLIBC_2.2.5'
/usr/bin/ld: note: 'dlclose@@GLIBC_2.2.5' is defined in DSO
/lib64/libdl.so.2 so try adding it to the linker command line
/lib64/libdl.so.2: could not read symbols: Invalid operation
collect2: ld returned 1 exit status
make[2]: *** [xdm] Error 1

Adding AC_SEARCH_LIBS([dlopen], [dl]) solves it, not sure there isn't
a better way to do it?

Thanks,