[PATCH 08/11] Makefile: correct "GIT-PERL-{DEFINES,HEADER}" dependency graph

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

Fix several small issues with the dependency graph of the generated
"GIT-PERL-DEFINES" and "GIT-PERL-HEADER" files:

1. Don't have "GIT-PERL-HEADER" depend on the "Makefile". That was a
   lazy way to over-declare the dependencies added in
   f6a0ad4be71 (Makefile: generate Perl header from template file,
   2018-04-10). Let's correct our dependency graph instead.

2. Don't have $(SCRIPT_PERL_GEN) (such as "git-send-email") depend on
   GIT-BUILD-OPTIONS. Let's instead use GIT-PERL-DEFINES.

   The reason for depending on "GIT-BUILD-OPTIONS" was to trigger a
   re-build if NO_PERL=Y was defined. We can instead add that variable
   to "PERL_DEFINES", and have "GIT-PERL-DEFINES" created and updated
   if "NO_PERL=Y" is defined.

3. Due to #2 we'll need to have GIT-PERL-DEFINES be generated even
   under NO_PERL, since that variable will be used by the
   "unimplemented.sh" script.

4. Don't depend on $(gitexecdir), $(perllibdir) and $(localedir),
   instead depend on the $(*_relative_SQ) versions of those.

   The latter is what we'll actually use, while it's unlikely to
   matter in practice (we'd just skip re-building these under
   RUNTIME_PREFIX if the relative path was the same) it makes the code
   easier to read.

   That's because this brings us to a 1=1 mapping of these variables
   and what's subsequently used in the "GIT-PERL-DEFINES",
   "GIT-PERL-HEADER" and "perl/build/lib/%.pm" rules below.

5. We don't need the substitution of " " for ":" added in
   07d90eadb50 (Makefile: add Perl runtime prefix support,
   2018-04-10), let's drop it. This doesn't matter for the correctness
   of these files, because unlike GIT-BUILD-OPTIONS nothing is
   consuming them except the Makefile itself.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 Makefile | 42 +++++++++++++++++++++++++-----------------
 1 file changed, 25 insertions(+), 17 deletions(-)

diff --git a/Makefile b/Makefile
index d488a723b79..356c98dff45 100644
--- a/Makefile
+++ b/Makefile
@@ -2298,10 +2298,14 @@ git.res: git.rc GIT-VERSION-FILE GIT-PREFIX
 	    $(shell echo $(GIT_VERSION) 0 0 0 0 | tr '.a-zA-Z-' ' '))) \
 	  -DGIT_VERSION="\\\"$(GIT_VERSION)\\\"" -i $< -o $@
 
-# This makes sure we depend on the NO_PERL setting itself.
-$(SCRIPT_PERL_GEN): GIT-BUILD-OPTIONS
+# Under NO_PERL=Y we'll still make GIT-PERL-DEFINES. We need to depend
+# on NO_PERL=Y itself for creating "unimplemented.sh" scripts.
+PERL_DEFINES =
+$(SCRIPT_PERL_GEN): GIT-PERL-DEFINES
 
 ifdef NO_PERL
+PERL_DEFINES += $(NO_PERL)
+
 $(SCRIPT_PERL_GEN) git-instaweb: % : unimplemented.sh
 	$(QUIET_GEN) \
 	sed -e '1s|#!.*/sh|#!$(SHELL_PATH_SQ)|' \
@@ -2310,22 +2314,26 @@ $(SCRIPT_PERL_GEN) git-instaweb: % : unimplemented.sh
 	chmod +x $@+ && \
 	mv $@+ $@
 else # NO_PERL
-# Used for substitution in Perl modules. Disabled when using RUNTIME_PREFIX
-# since the locale directory is injected.
+# The localedir is only used in Perl modules if !NO_GETTEXT
+ifndef NO_GETTEXT
 perl_localedir_SQ = $(localedir_SQ)
+endif
 
 PERL_HEADER_TEMPLATE = perl/header_templates/fixed_prefix.template.pl
-PERL_DEFINES =
+
 PERL_DEFINES += $(PERL_PATH_SQ)
 PERL_DEFINES += $(PERLLIB_EXTRA_SQ)
 PERL_DEFINES += $(perllibdir_SQ)
 PERL_DEFINES += $(RUNTIME_PREFIX)
 PERL_DEFINES += $(NO_PERL_CPAN_FALLBACKS)
 PERL_DEFINES += $(NO_GETTEXT)
-PERL_DEFINES += $(gitexecdir)
-PERL_DEFINES += $(perllibdir)
-PERL_DEFINES += $(localedir)
-PERL_DEFINES := $(subst $(space),:,$(PERL_DEFINES))
+ifdef RUNTIME_PREFIX
+PERL_DEFINES += $(gitexecdir_relative_SQ)
+PERL_DEFINES += $(perllibdir_relative_SQ)
+PERL_DEFINES += $(localedir_relative_SQ)
+else
+PERL_DEFINES += $(perllocaledir_SQ)
+endif
 
 ifdef RUNTIME_PREFIX
 PERL_HEADER_TEMPLATE = perl/header_templates/runtime_prefix.template.pl
@@ -2347,14 +2355,7 @@ $(SCRIPT_PERL_GEN): % : %.perl GIT-PERL-DEFINES GIT-PERL-HEADER GIT-VERSION-FILE
 	chmod +x $@+ && \
 	mv $@+ $@
 
-GIT-PERL-DEFINES: FORCE
-	@FLAGS='$(PERL_DEFINES)'; \
-	    if test x"$$FLAGS" != x"`cat $@ 2>/dev/null`" ; then \
-		echo >&2 "    * new perl-specific parameters"; \
-		echo "$$FLAGS" >$@; \
-	    fi
-
-GIT-PERL-HEADER: $(PERL_HEADER_TEMPLATE) GIT-PERL-DEFINES Makefile
+GIT-PERL-HEADER: $(PERL_HEADER_TEMPLATE) GIT-PERL-DEFINES
 	$(QUIET_GEN) \
 	INSTLIBDIR='$(perllibdir_SQ)' && \
 	INSTLIBDIR_EXTRA='$(PERLLIB_EXTRA_SQ)' && \
@@ -2380,6 +2381,13 @@ git-instaweb: git-instaweb.sh GIT-SCRIPT-DEFINES
 	mv $@+ $@
 endif # NO_PERL
 
+GIT-PERL-DEFINES: FORCE
+	@FLAGS='$(PERL_DEFINES)'; \
+	    if test x"$$FLAGS" != x"`cat $@ 2>/dev/null`" ; then \
+		echo >&2 "    * new perl-specific parameters"; \
+		echo "$$FLAGS" >$@; \
+	    fi
+
 # This makes sure we depend on the NO_PYTHON setting itself.
 $(SCRIPT_PYTHON_GEN): GIT-BUILD-OPTIONS
 
-- 
2.34.1.1119.g7a3fc8778ee