[PATCH 4/6] Makefile: make INSTALL_SYMLINKS affect the build directory

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Change the INSTALL_SYMLINKS flag to also affect whether a built-in
like e.g. git-fetch is a symlink or not in git's build directory.

This doesn't matter for anything other than as an aid to developers
who might be confused about their build not matching the installation,
and who'd like to be reminded that e.g. "git-fetch" is a built-in by
"ls" coloring appropriately it as a symlink.

In order to make this work we need to rebuild the relevant programs
when the INSTALL_SYMLINKS flag changes. This also ensures that we'll
install the right thing, we don't want a different "INSTALL_SYMLINKS"
setting during "make all" and "make install" to result in a broken
installation.

We will do the wrong thing here if both the SKIP_DASHED_BUILT_INS and
INSTALL_SYMLINKS are being flipped. But that's not a new bug:

A build with "INSTALL_SYMLINKS=Y SKIP_DASHED_BUILT_INS=" will result
in e.g. "git-fetch" being a symlink. When building again with
"INSTALL_SYMLINKS= SKIP_DASHED_BUILT_INS=Y", only unconditionally
built programs such as "git-upload-pack" will correctly be flipped to
a hardlink, but e.g. "git-fetch" will be left as a symlink.

That's an existing bug (or unexpected behavior) in the
SKIP_DASHED_BUILT_INS flag, not something new being introduced or made
worse here. It's a bit more noticeable now as we might not expect
these now-stale symlinks to be left behind, and "ls" (in some
configurations) will color them prominently.

But we'll still do the right thing on "make install" since we'll
ignore the likes of "git-fetch" there under "SKIP_DASHED_BUILT_INS=Y".
Under "SKIP_DASHED_BUILT_INS=" we'll correctly flip the symlink to a
hardlink or vice-versa if needed before installation.

Still, we should get around to fixing that SKIP_DASHED_BUILT_INS. You
can't reliably set that flag to "Y" for checking whether the tests
rely on the now-skipped dashed built-ins without first running "make
clean" (or knowing you've always been building with
SKIP_DASHED_BUILT_INS=Y).

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 .gitignore |  1 +
 Makefile   | 19 +++++++++++++++++--
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/.gitignore b/.gitignore
index 3dcdb6bb5ab..f90aa21b23b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,6 +5,7 @@
 /GIT-BUILD-OPTIONS
 /GIT-CFLAGS
 /GIT-LDFLAGS
+/GIT-LNCPFLAGS
 /GIT-PREFIX
 /GIT-PERL-DEFINES
 /GIT-PERL-HEADER
diff --git a/Makefile b/Makefile
index a4784f28f5b..29d9bade5a8 100644
--- a/Makefile
+++ b/Makefile
@@ -337,6 +337,11 @@ all::
 # NO_INSTALL_HARDLINKS. This will not produce any indirect symlinks, we will
 # always symlink to the final target directly.
 #
+# NO_INSTALL_HARDLINKS which will also use symlinking by indirection
+# within the same directory in some cases, INSTALL_SYMLINKS will
+# always symlink to the final target directly. This option also
+# affects dashed built-ins in the build directory pre-installation.
+#
 # Define NO_CROSS_DIRECTORY_HARDLINKS if you plan to distribute the installed
 # programs as a tar, where bin/ and libexec/ might be on different file systems.
 #
@@ -2197,9 +2202,12 @@ version.sp version.s version.o: EXTRA_CPPFLAGS = \
 		GIT_CEILING_DIRECTORIES="$(CURDIR)/.." \
 		git rev-parse -q --verify HEAD 2>/dev/null)"'
 
+$(BUILT_INS): GIT-LNCPFLAGS
 $(BUILT_INS): git$X
 	$(QUIET_BUILT_IN)$(RM) $@ && \
-	./ln-or-cp.sh $< $@
+	./ln-or-cp.sh \
+		--install-symlinks "$(INSTALL_SYMLINKS)" \
+		$< $@
 
 config-list.h: generate-configlist.sh
 
@@ -2548,9 +2556,12 @@ git-http-push$X: http.o http-push.o GIT-LDFLAGS $(GITLIBS)
 		$(CURL_LIBCURL) $(EXPAT_LIBEXPAT) $(LIBS) && \
 	mv $@+ $@
 
+$(REMOTE_CURL_ALIASES): GIT-LNCPFLAGS
 $(REMOTE_CURL_ALIASES): $(REMOTE_CURL_PRIMARY)
 	$(QUIET_LNCP)$(RM) $@ && \
-	./ln-or-cp.sh $< $@
+	./ln-or-cp.sh \
+		--install-symlinks "$(INSTALL_SYMLINKS)" \
+		$< $@
 
 $(REMOTE_CURL_PRIMARY): remote-curl.o http.o http-walker.o GIT-LDFLAGS $(GITLIBS)
 	$(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@+ $(ALL_LDFLAGS) $(filter %.o,$^) \
@@ -2742,6 +2753,10 @@ GIT-LDFLAGS: FORCE
 		echo "$$FLAGS" >GIT-LDFLAGS; \
             fi
 
+GIT-LNCPFLAGS: FORCE
+	@echo INSTALL_SYMLINKS=\''$(subst ','\'',$(subst ','\'',$(INSTALL_SYMLINKS)))'\' >$@+
+	@if cmp $@+ $@ >/dev/null 2>&1; then $(RM) $@+; else mv $@+ $@; fi
+
 # We need to apply sq twice, once to protect from the shell
 # that runs GIT-BUILD-OPTIONS, and then again to protect it
 # and the first level quoting from the shell that runs "echo".
-- 
2.31.1.461.gd47399f6574