[libvirt] [PATCH 5/6] m4: readline: Use pkg-config

With the 7.0 release, readline has finally started shipping pkg-config support in the form of a readline.pc file. Unfortunately, most downstreams have yet to catch up with this change: among Linux distributions in particular, Fedora Rawhide seems to be the only one installing it at the moment. Non-Linux operating systems have been faring much better in this regard: both FreeBSD (through ports) and macOS (through homebrew) include pkg-config support in their readline package. This is great news for us, since those are the platforms where pkg-config is more useful on account of them installing headers and libraries outside of the respective default search paths. Our implementation checks whether readline is registered as a pkg-config package, and if so obtains CFLAGS and LIBS using the tool; if not, we just keep using the existing logic. Signed-off-by: Andrea Bolognani <abologna(a)redhat.com&gt; --- m4/virt-readline.m4 | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/m4/virt-readline.m4 b/m4/virt-readline.m4 index a2788cb4aa..6fde47d2c8 100644 --- a/m4/virt-readline.m4 +++ b/m4/virt-readline.m4 @@ -23,8 +23,17 @@ AC_DEFUN([LIBVIRT_ARG_READLINE],[ AC_DEFUN([LIBVIRT_CHECK_READLINE],[ - # The normal library check... - LIBVIRT_CHECK_LIB([READLINE], [readline], [readline], [readline/readline.h]) + # We have to check for readline.pc's presence beforehand because for + # the longest time the library didn't ship a .pc file at all + PKG_CHECK_EXISTS([readline], [use_pkgconfig=1], [use_pkgconfig=0]) + + if test $use_pkgconfig = 1; then + # readline 7.0 is the first version which includes pkg-config support + LIBVIRT_CHECK_PKG([READLINE], [readline], [7.0]) + else + # The normal library check... + LIBVIRT_CHECK_LIB([READLINE], [readline], [readline], [readline/readline.h]) + fi # We need this to avoid compilation issues with modern compilers. # See 9ea3424a178 for a more detailed explanation -- 2.20.1