[PATCH/RFC] Makefile: build/install git-remote-<scheme> as hardlinks when able

[Junio C Hamano <gitster@pobox.com>]

Three git-remote-<scheme> helper programs are the same executable that
uses libcurl to implement the named protocol transfer.  Instead of
running the linker three times to build different programs, build one and
hardlink (or copy if the underlying filesystem does not support it) the
other two.

Install one to $(gitexecdir) and make the other two hardnlinks, in a way
similar to how we install programs that implement built-in commands.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---

I do not particularly like this one.  ALL_PROGRAMS does not include any of
the built-in programs, but because CURL_SYNONYMS are part of PROGRAMS, the
install step needs to filter them out, so that we can arrange to make
hardlinks to the synonyms in a separate step.

Putting git-remote-http$X on OTHER_PROGRAMS like we do for git$X does not
work well either, as that won't install it in gitexecdir.

 Makefile |   23 +++++++++++++++++++----
 1 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/Makefile b/Makefile
index e29b15f..438cffb 100644
--- a/Makefile
+++ b/Makefile
@@ -383,7 +383,8 @@ BUILT_INS += git-stage$X
 BUILT_INS += git-status$X
 BUILT_INS += git-whatchanged$X
 
-# what 'all' will build and 'install' will install, in gitexecdir
+# what 'all' will build and 'install' will install in gitexecdir,
+# excluding programs for built-in commands
 ALL_PROGRAMS = $(PROGRAMS) $(SCRIPTS)
 
 # what 'all' will build but not install in gitexecdir
@@ -980,7 +981,8 @@ else
 	else
 		CURL_LIBCURL = -lcurl
 	endif
-	PROGRAMS += git-remote-http$X git-remote-https$X git-remote-ftp$X git-http-fetch$X
+	CURL_SYNONYMS = git-remote-https$X git-remote-ftp$X
+	PROGRAMS += git-remote-http$X $(CURL_SYNONYMS) git-http-fetch$X
 	curl_check := $(shell (echo 070908; curl-config --vernum) | sort -r | sed -ne 2p)
 	ifeq "$(curl_check)" "070908"
 		ifndef NO_EXPAT
@@ -1256,6 +1258,7 @@ ifndef V
 	QUIET_LINK     = @echo '   ' LINK $@;
 	QUIET_BUILT_IN = @echo '   ' BUILTIN $@;
 	QUIET_GEN      = @echo '   ' GEN $@;
+	QUIET_LNCP     = @echo '   ' LN/CP $@;
 	QUIET_SUBDIR0  = +@subdir=
 	QUIET_SUBDIR1  = ;$(NO_SUBDIR) echo '   ' SUBDIR $$subdir; \
 			 $(MAKE) $(PRINT_DIR) -C $$subdir
@@ -1494,10 +1497,16 @@ git-http-push$X: revision.o http.o http-push.o $(GITLIBS)
 	$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) \
 		$(LIBS) $(CURL_LIBCURL) $(EXPAT_LIBEXPAT)
 
-git-remote-http$X git-remote-https$X git-remote-ftp$X: remote-curl.o http.o http-walker.o $(GITLIBS)
+git-remote-http$X: remote-curl.o http.o http-walker.o $(GITLIBS)
 	$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) \
 		$(LIBS) $(CURL_LIBCURL) $(EXPAT_LIBEXPAT)
 
+$(CURL_SYNONYMS): git-remote-http$X
+	$(QUIET_LNCP)$(RM) $@ && \
+	ln $< $@ 2>/dev/null || \
+	ln -s $< $@ 2>/dev/null || \
+	cp $< $@
+
 $(LIB_OBJS) $(BUILTIN_OBJS): $(LIB_H)
 $(patsubst git-%$X,%.o,$(PROGRAMS)) git.o: $(LIB_H) $(wildcard */*.h)
 builtin-revert.o wt-status.o: wt-status.h
@@ -1653,7 +1662,7 @@ export gitexec_instdir
 install: all
 	$(INSTALL) -d -m 755 '$(DESTDIR_SQ)$(bindir_SQ)'
 	$(INSTALL) -d -m 755 '$(DESTDIR_SQ)$(gitexec_instdir_SQ)'
-	$(INSTALL) $(ALL_PROGRAMS) '$(DESTDIR_SQ)$(gitexec_instdir_SQ)'
+	$(INSTALL) $(filter-out $(CURL_SYNONYMS), $(ALL_PROGRAMS)) '$(DESTDIR_SQ)$(gitexec_instdir_SQ)'
 	$(INSTALL) git$X git-upload-pack$X git-receive-pack$X git-upload-archive$X git-shell$X git-cvsserver '$(DESTDIR_SQ)$(bindir_SQ)'
 	$(MAKE) -C templates DESTDIR='$(DESTDIR_SQ)' install
 ifndef NO_PERL
@@ -1679,6 +1688,12 @@ endif
 		ln -s "git$X" "$$execdir/$$p" 2>/dev/null || \
 		cp "$$execdir/git$X" "$$execdir/$$p" || exit; \
 	  done; } && \
+	{ for p in $(CURL_SYNONYMS); do \
+		$(RM) "$$execdir/$$p" && \
+		ln "$$execdir/git-remote-http$X" "$$execdir/$$p" 2>/dev/null || \
+		ln -s "git-remote-http$X" "$$execdir/$$p" 2>/dev/null || \
+		cp "$$execdir/git-remote-http$X" "$$execdir/$$p" || exit; \
+	  done; } && \
 	./check_bindir "z$$bindir" "z$$execdir" "$$bindir/git-add$X"
 
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