build: Separate git operations from build operations.

Author: bhaible

.gitmodules

@@ -0,0 +1,3 @@
+[subcheckout "gnulib"]
+	url = git://git.savannah.gnu.org/gnulib.git
+	path = gnulib

ChangeLog

@@ -1,3 +1,12 @@
+2019-04-01  Bruno Haible  <bruno@clisp.org>
+
+	build: Separate git operations from build operations.
+	* gitsub.sh: New file, from gnulib.
+	* .gitmodules: New file.
+	* autogen.sh: Remove all git operations. Look at GNULIB_SRCDIR
+	environment variable. Ignore the GNULIB_TOOL environment variable.
+	* HACKING: Explain when to use gitsub.sh.
+
 2019-03-07  Bruno Haible  <bruno@clisp.org>
 
 	Avoid signed integer overflow during shifts.

HACKING

@@ -49,8 +49,14 @@ Access to the Git repository is described at
 https://savannah.gnu.org/git/?group=libiconv .
 
 After fetching the sources from the Git repository, peek at the comments in
-autogen.sh, then run "./autogen.sh"; then you can proceed with "./configure"
-as usual.
+autogen.sh, then run
+  ./gitsub.sh pull
+  ./autogen.sh
+Then you can proceed with "./configure" as usual.
+
+Each time you want to update the source, do not only "git pull".  Instead do
+  git pull && ./gitsub.sh pull
+  ./autogen.sh
 
 
 Adding new encodings

autogen.sh

@@ -5,10 +5,9 @@
 # with new versions of autoconf or automake.
 #
 # This script requires autoconf-2.63..2.69 and automake-1.11..1.16 in the PATH.
-# It also requires either
-#   - the GNULIB_TOOL environment variable pointing to the gnulib-tool script
-#     in a gnulib checkout, or
-#   - the git program in the PATH and an internet connection.
+# If not used from a released tarball, it also requires either
+#   - the GNULIB_SRCDIR environment variable pointing to a gnulib checkout, or
+#   - a preceding invocation of './gitsub.sh pull'.
 # It also requires
 #   - the gperf program.
 
@@ -28,12 +27,6 @@
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 # Usage: ./autogen.sh [--skip-gnulib]
-#
-# Usage from a git checkout:                 ./autogen.sh
-# This uses an up-to-date gnulib checkout.
-#
-# Usage from a released tarball:             ./autogen.sh --skip-gnulib
-# This does not use a gnulib checkout.
 
 skip_gnulib=false
 while :; do
@@ -44,28 +37,29 @@ while :; do
 done
 
 if test $skip_gnulib = false; then
-  if test -z "$GNULIB_TOOL"; then
-    # Check out gnulib in a subdirectory 'gnulib'.
-    if test -d gnulib; then
-      (cd gnulib && git pull)
-    else
-      git clone git://git.savannah.gnu.org/gnulib.git
-    fi
-    # Now it should contain a gnulib-tool.
-    if test -f gnulib/gnulib-tool; then
-      GNULIB_TOOL=`pwd`/gnulib/gnulib-tool
-    else
-      echo "** warning: gnulib-tool not found" 1>&2
-    fi
-  fi
-  # Skip the gnulib-tool step if gnulib-tool was not found.
-  if test -n "$GNULIB_TOOL"; then
-    $GNULIB_TOOL --copy-file build-aux/ar-lib || exit $?
-    chmod a+x build-aux/ar-lib || exit $?
-    make -f Makefile.devel \
-         gnulib-clean srclib/Makefile.gnulib gnulib-imported-files \
-         GNULIB_TOOL="$GNULIB_TOOL"
+  if test -n "$GNULIB_SRCDIR"; then
+    test -d "$GNULIB_SRCDIR" || {
+      echo "*** GNULIB_SRCDIR is set but does not point to an existing directory." 1>&2
+      exit 1
+    }
+  else
+    GNULIB_SRCDIR=`pwd`/gnulib
+    test -d "$GNULIB_SRCDIR" || {
+      echo "*** Subdirectory 'gnulib' does not yet exist. Use './gitsub.sh pull' to create it, or set the environment variable GNULIB_SRCDIR." 1>&2
+      exit 1
+    }
   fi
+  # Now it should contain a gnulib-tool.
+  GNULIB_TOOL="$GNULIB_SRCDIR/gnulib-tool"
+  test -f "$GNULIB_TOOL" || {
+    echo "*** gnulib-tool not found." 1>&2
+    exit 1
+  }
+  $GNULIB_TOOL --copy-file build-aux/ar-lib || exit $?
+  chmod a+x build-aux/ar-lib || exit $?
+  make -f Makefile.devel \
+       gnulib-clean srclib/Makefile.gnulib gnulib-imported-files \
+       GNULIB_TOOL="$GNULIB_TOOL"
 fi
 
 make -f Makefile.devel totally-clean all || exit $?