The default behavior, for AC_CHECK_LIB when the `action-if-found` is NOT
defined, is to prepend the library to LIBS. [1]
"
If action-if-found is not specified, the default action prepends
-llibrary to LIBS and defines ‘HAVE_LIBlibrary’ (in all capitals).
"
It is important to note that the LIBS variable is used for ALL linking.
This is normally not a problem for most distribution since they force
the use of `--as-needed` at the toolchain level (gcc specs) (for example
debian [2]). One could also pass the `--as-needed` flag manually but
libtool reorganize flags in the case of shared object creation [3].
In our case, we always explicitly state the dependencies via the *_LIBADD
automake clause. We do not rely on the LIBS variable.
[1] https://www.gnu.org/software/autoconf/manual/autoconf-2.69/html_node/Libraries.html
[2] https://salsa.debian.org/toolchain-team/gcc/-/blob/master/debian/patches/gcc-as-needed.diff
[3] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=347650
Change-Id: Iea7812ccabb17e976362f9ea9412e0834ce946f4
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/6745
Tested-by: jenkins <jenkins@lttng.org>
Reviewed-by: Simon Marchi <simon.marchi@efficios.com>
Reviewed-by: Jonathan Rajotte Julien <jonathan.rajotte-julien@efficios.com>
# Turns out SLES12 doesn't bother shipping .pc file for libelf
AC_MSG_WARN([Finding libelf without pkg-config.])
# Turns out SLES12 doesn't bother shipping .pc file for libelf
AC_MSG_WARN([Finding libelf without pkg-config.])
- AC_CHECK_LIB([elf], [elf_version], [], [AC_MSG_ERROR(Missing libelf (from elfutils >= 0.154) which is required by debug info. You can disable this feature using --disable-debug-info.)])
- AC_CHECK_LIB([dw], [dwarf_begin], [], [AC_MSG_ERROR(Missing libdw (from elfutils >= 0.154) which is required by debug info. You can disable this feature using --disable-debug-info.)])
+ AC_CHECK_LIB([elf], [elf_version], [:], [AC_MSG_ERROR(Missing libelf (from elfutils >= 0.154) which is required by debug info. You can disable this feature using --disable-debug-info.)])
+ AC_CHECK_LIB([dw], [dwarf_begin], [:], [AC_MSG_ERROR(Missing libdw (from elfutils >= 0.154) which is required by debug info. You can disable this feature using --disable-debug-info.)])
AE_LIB_ELFUTILS([0], [154], [], [AC_MSG_ERROR(elfutils >= 0.154 is required to use the debug info feature. You can disable this feature using --disable-debug-info.)])
ELFUTILS_LIBS="-lelf -ldw"
])
AE_LIB_ELFUTILS([0], [154], [], [AC_MSG_ERROR(elfutils >= 0.154 is required to use the debug info feature. You can disable this feature using --disable-debug-info.)])
ELFUTILS_LIBS="-lelf -ldw"
])