maintainer-makefile: Determine gnulib's location on disk correctly

maintainer-makefile: Determine gnulib's location on disk correctly

[Bruno Haible]

The sc_copyright_check syntax check is hitting me badly, due to an incorrect
determination of 'gnulib_dir' in maint.mk.

What I've done is:
  - set GNULIB_SRCDIR to point to my current Gnulib checkout,
  - checked out GNU grep from git,
  - ran './bootstrap --gnulib-srcdir=$GNULIB_SRCDIR --no-git' so that it
    actually uses this gnulib, instead of the gnulib subdirectory that
    I used in some previous builds in 2017,
  - run './configure && make dist'
It stops like this:
...
copyright_check
./gnulib/lib/version-etc.c
maint.mk: out of date copyright in ./gnulib/lib/version-etc.c; update it
make[4]: *** [maint.mk:1287: sc_copyright_check] Error 1
make[4]: Leaving directory '/media/develdata/devel/GREP/grep'

The copyright of ./gnulib/lib/version-etc.c is 2017. It's not up-to-date,
but it's not the gnulib checkout that I'm using. The one I'm using, I have
indicated through the GNULIB_SRCDIR environment variable.

This patch fixes it. The older commit, from Simon on 2021-01-26, said
  "Mimic bootstrap's gnulib-srcdir guessing."
and `bootstrap --help` (of the older bootstrap version in GNU grep) says
" * If this package is in a git repository with a 'gnulib' submodule
   configured, then that submodule is initialized and updated and sources
   are fetched from there.  If $GNULIB_SRCDIR is set (directly or via
   --gnulib-srcdir) and is a git repository, then it is used as a reference."
but that is not what it actually does: In my case, the 'gnulib' submodule
existed and was configured *and* GNULIB_SRCDIR was set, and 'bootstrap'
did NOT update it. This wrong --help output is one of the things that I
fixed on 2022-07-24.
The new logic in maint.mk reflects the (corrected and now correctly
documented) logic in 'bootstrap'.


2023-01-29  Bruno Haible  <bruno@clisp.org>

	maintainer-makefile: Determine gnulib's location on disk correctly.
	* top/maint.mk (gnulib_dir): Give priority to $(GNULIB_SRCDIR) over
	$(srcdir)/gnulib.

diff --git a/top/maint.mk b/top/maint.mk
index 034e25be3d..44f3db9d9d 100644
--- a/top/maint.mk
+++ b/top/maint.mk
@@ -64,10 +64,10 @@ VC_LIST = $(srcdir)/$(_build-aux)/vc-list-files -C $(srcdir)
 
 # You can override this variable in cfg.mk if your gnulib submodule lives
 # in a different location.
-gnulib_dir ?= $(shell if test -f $(srcdir)/gnulib/gnulib-tool; then \
-			echo $(srcdir)/gnulib; \
+gnulib_dir ?= $(shell if test -n "$(GNULIB_SRCDIR)" && test -f "$(GNULIB_SRCDIR)/gnulib-tool"; then \
+			echo "$(GNULIB_SRCDIR)"; \
 		else \
-			echo ${GNULIB_SRCDIR}; \
+			echo $(srcdir)/gnulib; \
 		fi)
 
 # You can override this variable in cfg.mk to set your own regexp