Hi,

when I tried to use --with-babeltrace on Fedora Rawhide x86_64
using gcc-4.9.1-3.fc22.x86_64 I got:

checking for libbabeltrace... no
configure: error: babeltrace is missing or unusable
Makefile:7973: recipe for target 'configure-gdb' failed

configure:15890: checking for libbabeltrace
configure:15918: gcc -o conftest -O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches  -m64 -mtune=generic   -Werror   -static-libstdc++ -static-libgcc -Wl,-z,relro    conftest.c -lselinux -lncurses -lz -lm  -ldl   /usr/lib64/libbabeltrace.so /usr/lib64/libbabeltrace-ctf.so >&5
conftest.c: In function 'main':
conftest.c:198:21: error: unused variable 'pos' [-Werror=unused-variable]
 struct bt_iter_pos *pos = bt_iter_get_pos (bt_ctf_get_iter (NULL));
                     ^
cc1: all warnings being treated as errors
configure:15918: $? = 1
configure: failed program was:

The patch below fixes it for me.

In configure.ac there is above this check:
  # Append -Werror to CFLAGS so that configure can catch the warning
  # "assignment from incompatible pointer type", which is related to
  # the babeltrace change from 1.0.3 to 1.1.0.  Babeltrace 1.1.0 works
  # in GDB, while babeltrace 1.0.3 is broken.
  # AC_LIB_HAVE_LINKFLAGS may modify CPPFLAGS in it, so it should be
  # safe to save and restore CFLAGS here.
  saved_CFLAGS=$CFLAGS
  CFLAGS="$CFLAGS -Werror"

Maybe it would be easier to use there:
  CFLAGS="$CFLAGS -Werror -Wno-unused-variable"

But maybe -Werror is cross-compiler compatible while -Wno-unused-variable is
not, I have no idea.


Jan