[PATCH] Allow building GIT in a different directory from the source directory

[Han-Wen Nienhuys <hanwen@xs4all.nl>]

GIT can now be built in a separate builddirectory. This is done as
follows:

  mkdir build
  cd build
  $my_git_dir/configure
  make

In this case, configure creates an empty directory tree based on the
source directory, and wraps Makefiles from source directory in the
build directory.  The rest of the functionality is delivered with the
VPATH feature of Make.

To make this work the Makefile should not mention ./ explicitly in
rules, but rather use $< and $^ to automatically look in the source
dir too.

perl/Makefile and perl/Makefile.PL need special massaging because perl
is not VPATH aware.

The documentation subdirectory has limited support for separate building, 
as asciidoc doesn't have a --include-path option.

 Documentation/Makefile |   36 ++++++++++++++++++++++--------------
 INSTALL                |    7 +++++++
 Makefile               |   23 ++++++++++++++---------
 config.mak.in          |    9 ++++-----
 configure.ac           |   34 ++++++++++++++++++++++++++++++++++
 generate-cmdlist.sh    |    2 +-
 perl/Makefile          |    4 ++++
 perl/Makefile.PL       |   16 +++++++++++++---
 8 files changed, 99 insertions(+), 32 deletions(-)

diff --git a/Documentation/Makefile b/Documentation/Makefile
index c00f5f6..39bcd45 100644
--- a/Documentation/Makefile
+++ b/Documentation/Makefile
@@ -1,6 +1,6 @@
 MAN1_TXT= \
-	$(filter-out $(addsuffix .txt, $(ARTICLES) $(SP_ARTICLES)), \
-		$(wildcard git-*.txt)) \
+	$(filter-out $(foreach i, $(ARTICLES) $(SP_ARTICLES), $(here-srcdir)/$(i).txt), \
+		$(wildcard $(here-srcdir)/git-*.txt)) \
 	gitk.txt
 MAN7_TXT=git.txt
 
@@ -33,8 +33,16 @@ # DESTDIR=
 
 INSTALL?=install
 
--include ../config.mak.autogen
+ifndef srcdir
+srcdir=..
+endif
+
+
+here-srcdir=$(srcdir)/Documentation
 
+ASCIIDOC_CONF=$(here-srcdir)/asciidoc.conf
+
+-include ../config.mak.autogen
 #
 # Please note that there is a minor bug in asciidoc.
 # The version after 6.0.3 _will_ include the patch found here:
@@ -63,9 +71,9 @@ install: man
 #
 # Determine "include::" file references in asciidoc files.
 #
-doc.dep : $(wildcard *.txt) build-docdep.perl
+doc.dep : $(wildcard $(here-srcdir)/*.txt) build-docdep.perl
 	rm -f $@+ $@
-	perl ./build-docdep.perl >$@+
+	perl $(lastword $^) >$@+
 	mv $@+ $@
 
 -include doc.dep
@@ -80,35 +88,35 @@ clean:
 	rm -f *.xml *.html *.1 *.7 howto-index.txt howto/*.html doc.dep README
 
 %.html : %.txt
-	asciidoc -b xhtml11 -d manpage -f asciidoc.conf $<
+	asciidoc -b xhtml11 -d manpage -f $(ASCIIDOC_CONF) $<
 
 %.1 %.7 : %.xml
-	xmlto -m callouts.xsl man $<
+	xmlto --searchpath $(here-srcdir)/  -m callouts.xsl man $<
 
 %.xml : %.txt
-	asciidoc -b docbook -d manpage -f asciidoc.conf $<
+	asciidoc -b docbook -d manpage -f $(ASCIIDOC_CONF) $<
 
 git.html: git.txt README
 
 glossary.html : glossary.txt sort_glossary.pl
 	cat $< | \
-	perl sort_glossary.pl | \
+	perl $(lastword $^) | \
 	asciidoc -b xhtml11 - > glossary.html
 
-howto-index.txt: howto-index.sh $(wildcard howto/*.txt)
+howto-index.txt: howto-index.sh $(wildcard $(here-srcdir)/howto/*.txt)
 	rm -f $@+ $@
-	sh ./howto-index.sh $(wildcard howto/*.txt) >$@+
+	sh $^ >$@+
 	mv $@+ $@
 
 $(patsubst %,%.html,$(ARTICLES)) : %.html : %.txt
-	asciidoc -b xhtml11 $*.txt
+	asciidoc -b xhtml11 $<
 
 WEBDOC_DEST = /pub/software/scm/git/docs
 
-$(patsubst %.txt,%.html,$(wildcard howto/*.txt)): %.html : %.txt
+$(patsubst %.txt,%.html,$(wildcard $(here-srcdir)/howto/*.txt)): %.html : %.txt
 	rm -f $@+ $@
 	sed -e '1,/^$$/d' $< | asciidoc -b xhtml11 - >$@+
 	mv $@+ $@
 
 install-webdoc : html
-	sh ./install-webdoc.sh $(WEBDOC_DEST)
+	sh $(here-srcdir)/install-webdoc.sh $(WEBDOC_DEST)
diff --git a/INSTALL b/INSTALL
index 8f69039..b1355fa 100644
--- a/INSTALL
+++ b/INSTALL
@@ -21,6 +21,13 @@ set up install paths (via config.mak.aut
 	$ make all doc ;# as yourself
 	# make install install-doc ;# as root
 
+When using configure, git may be built in a separate directory. Use
+
+	$ mkdir builddir
+	$ cd builddir
+	$ GIT-SOURCE-DIR/configure [options]
+	$ make
+	# make install                          
 
 Issues of note:
 
diff --git a/Makefile b/Makefile
index a1861de..8e6ec62 100644
--- a/Makefile
+++ b/Makefile
@@ -97,7 +97,7 @@ # MakeMaker (e.g. using ActiveState unde
 #
 
 GIT-VERSION-FILE: .FORCE-GIT-VERSION-FILE
-	@$(SHELL_PATH) ./GIT-VERSION-GEN
+	@$(SHELL_PATH) $(srcdir)/GIT-VERSION-GEN
 -include GIT-VERSION-FILE
 
 uname_S := $(shell sh -c 'uname -s 2>/dev/null || echo not')
@@ -110,15 +110,20 @@ # CFLAGS and LDFLAGS are for the users t
 
 CFLAGS = -g -O2 -Wall
 LDFLAGS =
-ALL_CFLAGS = $(CFLAGS)
+ALL_CFLAGS = $(CFLAGS) -I.
 ALL_LDFLAGS = $(LDFLAGS)
 STRIP ?= strip
 
 prefix = $(HOME)
 bindir = $(prefix)/bin
 gitexecdir = $(bindir)
-template_dir = $(prefix)/share/git-core/templates/
-# DESTDIR=
+datadir = $(prefix)/share
+GIT_datadir = $(datadir)/git-core
+template_dir = $(GIT_datadir)/templates/
+srcdir = .
+
+# this is usually set on the make command line.
+DESTDIR=
 
 # default configuration for gitweb
 GITWEB_CONFIG = gitweb_config.perl
@@ -595,8 +600,8 @@ git-merge-recur$X: git-merge-recursive$X
 $(BUILT_INS): git$X
 	rm -f $@ && ln git$X $@
 
-common-cmds.h: Documentation/git-*.txt
-	./generate-cmdlist.sh > $@+
+common-cmds.h: $(wildcard $(srcdir)/Documentation/git-*.txt)
+	$(srcdir)/generate-cmdlist.sh $(srcdir)/Documentation/ > $@+
 	mv $@+ $@
 
 $(patsubst %.sh,%,$(SCRIPT_SH)) : % : %.sh
@@ -605,7 +610,7 @@ common-cmds.h: Documentation/git-*.txt
 	    -e 's|@@PERL@@|$(PERL_PATH_SQ)|g' \
 	    -e 's/@@GIT_VERSION@@/$(GIT_VERSION)/g' \
 	    -e 's/@@NO_CURL@@/$(NO_CURL)/g' \
-	    $@.sh >$@+
+	    $^ >$@+
 	chmod +x $@+
 	mv $@+ $@
 
@@ -626,7 +631,7 @@ perl/perl.mak: GIT-CFLAGS
 	    -e '}' \
 	    -e 's|@@INSTLIBDIR@@|'"$$INSTLIBDIR"'|g' \
 	    -e 's/@@GIT_VERSION@@/$(GIT_VERSION)/g' \
-	    $@.perl >$@+
+	    $^ >$@+
 	chmod +x $@+
 	mv $@+ $@
 
@@ -670,7 +675,7 @@ git-instaweb: git-instaweb.sh gitweb/git
 	    -e '/@@GITWEB_CGI@@/d' \
 	    -e '/@@GITWEB_CSS@@/r gitweb/gitweb.css' \
 	    -e '/@@GITWEB_CSS@@/d' \
-	    $@.sh > $@+
+	    $< > $@+
 	chmod +x $@+
 	mv $@+ $@
 
diff --git a/config.mak.in b/config.mak.in
index 9a57840..bfbbf46 100644
--- a/config.mak.in
+++ b/config.mak.in
@@ -10,17 +10,16 @@ #INSTALL = @INSTALL@		# needs install-sh
 prefix = @prefix@
 exec_prefix = @exec_prefix@
 bindir = @bindir@
-#gitexecdir = @libexecdir@/git-core/
+mandir=@mandir@
+
+## unused, but necessary for some autoconf versions (?)
 datarootdir = @datarootdir@
-template_dir = @datadir@/git-core/templates/
 
-mandir=@mandir@
 
 srcdir = @srcdir@
-VPATH = @srcdir@
 
 export exec_prefix mandir
-export srcdir VPATH
+export srcdir 
 
 NEEDS_SSL_WITH_CRYPTO=@NEEDS_SSL_WITH_CRYPTO@
 NO_OPENSSL=@NO_OPENSSL@
diff --git a/configure.ac b/configure.ac
index 34e3478..403c410 100644
--- a/configure.ac
+++ b/configure.ac
@@ -5,6 +5,7 @@ AC_PREREQ(2.59)
 AC_INIT([git], [@@GIT_VERSION@@], [git@vger.kernel.org])
 
 AC_CONFIG_SRCDIR([git.c])
+srcdir=`cd $srcdir && pwd`
 
 config_file=config.mak.autogen
 config_append=config.mak.append
@@ -334,6 +335,39 @@ ## Output files
 AC_CONFIG_FILES(["${config_file}":"${config_in}":"${config_append}"])
 AC_OUTPUT
 
+if test "$srcdir" != "."; then
+
+  ## if we're building in another directory
+  ## we need to set it up like the sourcedir
+  for d in `cd $srcdir &&  find . -type d -print | grep -v '\.git'` ;
+  do
+    if test ! -d  $d ; then
+      echo creating $d 
+      mkdir $d
+    fi
+
+    if test -f $srcdir/$d/Makefile ; then
+
+      dnl [[]] is to keep m4 happy
+      depth=`echo $d/ | sed -e 's!^\./!!g' -e 's![[^/]]*/!../!g'`
+      echo creating $d/Makefile
+
+      if test "$depth"  = "";  then
+        INCLUDE_AUTOGEN="include config.mak.autogen" ;
+      else
+        INCLUDE_AUTOGEN="srcdir=$srcdir" 
+      fi
+ 
+      cat << EOF > $d/Makefile
+$INCLUDE_AUTOGEN
+VPATH = $srcdir/$d
+export VPATH
+include $srcdir/$d/Makefile
+EOF
+
+    fi 
+  done
+fi
 
 ## Cleanup
 rm -f "${config_append}"
diff --git a/generate-cmdlist.sh b/generate-cmdlist.sh
index 5450918..e744fbb 100755
--- a/generate-cmdlist.sh
+++ b/generate-cmdlist.sh
@@ -47,6 +47,6 @@ do
             x
             s/.*git-'"$cmd"' - \(.*\)/  {"'"$cmd"'", "\1"},/
 	    p
-     }' "Documentation/git-$cmd.txt"
+     }' "$1/git-$cmd.txt"
 done
 echo "};"
diff --git a/perl/Makefile b/perl/Makefile
index 099beda..ae61cf6 100644
--- a/perl/Makefile
+++ b/perl/Makefile
@@ -28,6 +28,10 @@ instdir_SQ = $(subst ','\'',$(prefix)/li
 	echo instlibdir: >> $@
 	echo '	echo $(instdir_SQ)' >> $@
 else
+
+PERL_SRCDIR=$(srcdir)/perl
+export PERL_SRCDIR
+
 $(makfile): Makefile.PL ../GIT-CFLAGS
 	'$(PERL_PATH_SQ)' $< PREFIX='$(prefix_SQ)'
 endif
diff --git a/perl/Makefile.PL b/perl/Makefile.PL
index 4168775..c136231 100644
--- a/perl/Makefile.PL
+++ b/perl/Makefile.PL
@@ -8,21 +8,31 @@ instlibdir:
 MAKE_FRAG
 }
 
-my %pm = ('Git.pm' => '$(INST_LIBDIR)/Git.pm');
+
+$src_prefix = "";
+if (defined ($ENV{PERL_SRCDIR})) {
+    $src_prefix = "$ENV{PERL_SRCDIR}/"
+}
+
+
+my %pm = ("$src_prefix/Git.pm" => '$(INST_LIBDIR)/Git.pm');
+
+
 
 # We come with our own bundled Error.pm. It's not in the set of default
 # Perl modules so install it if it's not available on the system yet.
 eval { require Error };
 if ($@) {
-	$pm{'private-Error.pm'} = '$(INST_LIBDIR)/Error.pm';
+	$pm{"$src_prefix/private-Error.pm"} = '$(INST_LIBDIR)/Error.pm';
 }
 
 my %extra;
 $extra{DESTDIR} = $ENV{DESTDIR} if $ENV{DESTDIR};
 
+
 WriteMakefile(
 	NAME            => 'Git',
-	VERSION_FROM    => 'Git.pm',
+	VERSION_FROM    => "$src_prefix/Git.pm",
 	PM		=> \%pm,
 	MAKEFILE	=> 'perl.mak',
 	%extra
 
 
-- 
 Han-Wen Nienhuys - hanwen@xs4all.nl - http://www.xs4all.nl/~hanwen