Makefile: add a dist target to generate a tarball

src/Makefile

@@ -20,6 +20,8 @@ else
     endif
 endif
 
+version ?= $(shell if [ -f .version ]; then cat .version; elif  [ -d ../.git ]; then git rev-parse --short HEAD; else echo "unknown"; fi )
+
 sources := $(sort $(wildcard *.cc))
 objects := $(addprefix ., $(sources:.cc=$(suffix).o))
 deps := $(addprefix ., $(sources:.cc=$(suffix).d))
@@ -75,14 +77,21 @@ all : kak
 kak : kak$(suffix)
 	ln -sf $< $@
 
-kak$(suffix) : $(objects)
-	$(CXX) $(LDFLAGS) $(CXXFLAGS) $(objects) $(LIBS) -o $@
+kak$(suffix) : $(objects) .version.o
+	$(CXX) $(LDFLAGS) $(CXXFLAGS) $(objects) .version.o $(LIBS) -o $@
 
 -include $(deps)
 
 .%$(suffix).o: %.cc
 	$(CXX) $(CPPFLAGS) $(CXXFLAGS) -MD -MP -MF $(addprefix ., $(<:.cc=$(suffix).d)) -c -o $@ $<
 
+.version.o: .version.cc
+	$(CXX) $(CPPFLAGS) $(CXXFLAGS) -c -o $@ $<
+	
+.version.cc: FORCE
+	@printf "%s" 'namespace Kakoune { const char* version = "$(version)"; }' > .version.cc.tmp
+	@if cmp -s .version.cc.tmp .version.cc; then rm .version.cc.tmp; else mv .version.cc.tmp .version.cc; fi
+
 # Generate the man page
 ifeq ($(gzip_man),yes)
 ../doc/kak.1.gz: ../doc/kak.1.asciidoc
@@ -106,6 +115,16 @@ tags:
 clean:
 	rm -f .*.o .*.d
 
+dist:
+	@if ! [ -d ../.git ]; then echo "make dist can only run from a git repo";  false; fi
+	@if git status -s | grep -qEv '^\?\?'; then echo "working tree is not clean";  false; fi
+	cd ../;                                                                               \
+	git archive --format=tar --prefix=kakoune-$(version)/ HEAD -o kakoune-$(version).tar; \
+	echo "$(version)" > src/.version;                                                     \
+	tar --transform "s,^,kakoune-$(version)/," -rf kakoune-$(version).tar src/.version;   \
+	rm src/.version;                                                                      \
+	bzip2 kakoune-$(version).tar;
+
 distclean: clean
 	rm -f kak kak$(suffix)
 	find ../doc -type f \( -name \*\\.gz -o -name \*\\.1 \) -exec rm -f '{}' +
@@ -146,5 +165,5 @@ uninstall:
 		$(mandir)/kak.1.gz \
 		$(mandir)/kak.1
 
-.PHONY: check TAGS clean distclean installdirs install install-strip uninstall
-.PHONY: tags test man kak
+.PHONY: check TAGS clean dist distclean installdirs install install-strip uninstall
+.PHONY: tags test man kak FORCE