[libvirt] [PATCH] build: fix autogen rule for VPATH build

[Jim Meyering]

Eric Blake wrote:
> * cfg.mk (gnulib_srcdir): Override maint.mk default.
> (_update_required): Run in correct directory.
> ---
>
> I noticed an error message about bootstrap.conf not found when trying
> to do a VPATH build for my new clang setup.
>
> This subsumes up my earlier patch to declare the correct gnulib_srcdir,
> as noticed by Jim, but does not advance to a newer .gnulib, as there
> are some other issues to fix on that front first.
>
>  cfg.mk |    4 ++++
>  1 files changed, 4 insertions(+), 0 deletions(-)
>
> diff --git a/cfg.mk b/cfg.mk
> index 105b625..a6e9204 100644
> --- a/cfg.mk
> +++ b/cfg.mk
> @@ -24,6 +24,9 @@ gnu_rel_host = $(gnu_ftp_host-$(RELEASE_TYPE))
>  url_dir_list = \
>    ftp://$(gnu_rel_host)/gnu/coreutils
>
> +# We use .gnulib, not gnulib.
> +gnulib_srcdir = $(srcdir)/.gnulib
> +
>  # Tests not to run as part of "make distcheck".
>  local-checks-to-skip =			\
>    changelog-check			\
> @@ -282,6 +285,7 @@ ifeq (0,$(MAKELEVEL))
>    # b653eda3ac4864de205419d9f41eec267cb89eeb
>    _submodule_hash = sed 's/^[ +-]//;s/ .*//'
>    _update_required := $(shell						\
> +      cd '$(srcdir)';							\
>        actual=$$(git submodule status | $(_submodule_hash);		\
>  		git hash-object bootstrap.conf;				\
>  		git diff .gnulib);					\

ACK.
FYI, I never encountered a need for that "cd" before, in testing VPATH
builds, because my first step was always to run ./autogen.sh && distclean
from the srcdir, not realizing that e.g., ../autogen.sh (from the build
dir) was supposed to work, too.