lttng-tools-2.14.0-rc1: fails to compile with libxml2-2.14.4

[Norbert Lange]

Am Di., 17. Juni 2025 um 16:50 Uhr schrieb Kienan Stewart
<kstewart at efficios.com>:
>
> Hi Norbert,
>
> On 6/17/25 10:15 AM, Norbert Lange via lttng-dev wrote:
> > /tmp/dev_develop_libxml2/usr/include/libxml2/libxml/encoding.h:173:7:
> > note: declared here
> >    173 |     } input XML_DEPRECATED_MEMBER;
> >        |       ^~~~~
> > ../../../src/common/config/session-config.cpp:297:75: error: no match
> > for call to '(_xmlCharEncodingHandler::<unnamed union>) (xmlChar*&,
> > int*, const xmlChar*, int*)'
> >    297 |  ret = handler->input(out_str, &out_len, (const xmlChar *)
> > in_str, &in_len);
> >        |
> >             ^
> >
> > Changing the call to handler->input.legacyFunc seems to fix it.
> >
> > Also lttng seems to need libxml2, but doesnt add the necessary flags.
> >
>
> Regarding the "necessary flags" for libxml2 when building the lttng
> binary, could you indicate clearly the error you have?
>
> All uses of libxml2 are via libconfig, and the libxml2 LD flags are
> added to lttng via libconfig.la.
>
> When performing the final link of lttng, I see `-lxml2` in the command line.
>
> thanks,
> kienan
> > Regards, Norbert
>

The error is, that I don't see -lxml2 in the commandline (unless I use
the global LDFLAGS), libconfig.la does not contain the flags either.
However, the Makefiles all contain them:

src/common/Makefile:libxml2_CFLAGS =
-I/tmp/dev_develop_libxml2/usr/include/libxml2
src/common/Makefile:libxml2_LIBS =
/tmp/dev_develop_libxml2/usr/local/lib/libxml2.so

I dont use pkgconf, I set the variables directly (libxml2 is not a
part of our production filesystem + compiler and right now I just
barely managed to compile lttng somehow).

Regards, Norbert