Re: [PATCH v4 2/4] Makefile: add support for "perllibdir"

> Add the "perllibdir" Makefile variable, which allows the customization
> of the Perl library installation path.
>
> The Perl library installation path is currently left entirely to the
> Perl Makefile implementation, either MakeMaker (default) or a fixed path
> when NO_PERL_MAKEMAKER is enabled. This patch introduces "perllibdir", a
> Makefile variable that can override that Perl module installation path.
>
> As with some other Makefile variables, "perllibdir" may be either
> absolute or relative. In the latter case, it is treated as relative to
> "$(prefix)".
>
> Add some incidental documentation to perl/Makefile.
>
> Explicitly specifying an installation path is necessary for Perl runtime
> prefix support, as runtime prefix resolution code must know in advance
> where the Perl support modules are installed.
>
> Signed-off-by: Dan Jacques <dnj@google.com>
> ---
>  Makefile      | 18 +++++++++++++-----
>  perl/Makefile | 52 ++++++++++++++++++++++++++++++++++++++++++++++------
>  2 files changed, 59 insertions(+), 11 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index f7c4ac207..80904f8b0 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -462,6 +462,7 @@ ARFLAGS = rcs
>  #   mandir
>  #   infodir
>  #   htmldir
> +#   perllibdir
>  # This can help installing the suite in a relocatable way.
>
>  prefix = $(HOME)
> @@ -1721,6 +1722,7 @@ gitexecdir_SQ = $(subst ','\'',$(gitexecdir))
>  template_dir_SQ = $(subst ','\'',$(template_dir))
>  htmldir_relative_SQ = $(subst ','\'',$(htmldir_relative))
>  prefix_SQ = $(subst ','\'',$(prefix))
> +perllibdir_SQ = $(subst ','\'',$(perllibdir))
>  gitwebdir_SQ = $(subst ','\'',$(gitwebdir))
>
>  SHELL_PATH_SQ = $(subst ','\'',$(SHELL_PATH))
> @@ -1955,17 +1957,22 @@ $(SCRIPT_PERL_GEN): perl/perl.mak
>
>  perl/perl.mak: perl/PM.stamp
>
> -perl/PM.stamp: FORCE
> +perl/PM.stamp: GIT-PERL-DEFINES FORCE
>  	@$(FIND) perl -type f -name '*.pm' | sort >$@+ && \
> +	cat GIT-PERL-DEFINES >>$@+ && \
>  	$(PERL_PATH) -V >>$@+ && \
>  	{ cmp $@+ $@ >/dev/null 2>/dev/null || mv $@+ $@; } && \
>  	$(RM) $@+
>
> -perl/perl.mak: GIT-CFLAGS GIT-PREFIX perl/Makefile perl/Makefile.PL
> -	$(QUIET_SUBDIR0)perl $(QUIET_SUBDIR1) PERL_PATH='$(PERL_PATH_SQ)' prefix='$(prefix_SQ)' $(@F)
> -
>  PERL_HEADER_TEMPLATE = perl/header_fixed_prefix.pl.template
> -PERL_DEFINES = $(PERL_PATH_SQ):$(PERLLIB_EXTRA_SQ)
> +
> +PERL_DEFINES := $(PERL_PATH_SQ) $(PERLLIB_EXTRA_SQ)
> +PERL_DEFINES += $(NO_PERL_MAKEMAKER)
> +PERL_DEFINES += $(perllibdir)
> +
> +perl/perl.mak: GIT-CFLAGS GIT-PREFIX perl/Makefile perl/Makefile.PL
> +	$(QUIET_SUBDIR0)perl $(QUIET_SUBDIR1) PERL_PATH='$(PERL_PATH_SQ)' \
> +	  prefix='$(prefix_SQ)' perllibdir='$(perllibdir_SQ)' $(@F)
>
>  $(SCRIPT_PERL_GEN): % : %.perl perl/perl.mak GIT-PERL-DEFINES GIT-PERL-HEADER GIT-VERSION-FILE
>  	$(QUIET_GEN)$(RM) $@ $@+ && \
> @@ -1979,6 +1986,7 @@ $(SCRIPT_PERL_GEN): % : %.perl perl/perl.mak GIT-PERL-DEFINES GIT-PERL-HEADER GI
>  	chmod +x $@+ && \
>  	mv $@+ $@
>
> +PERL_DEFINES := $(subst $(space),:,$(PERL_DEFINES))
>  GIT-PERL-DEFINES: FORCE
>  	@FLAGS='$(PERL_DEFINES)'; \
>  	    if test x"$$FLAGS" != x"`cat $@ 2>/dev/null`" ; then \
> diff --git a/perl/Makefile b/perl/Makefile
> index f657de20e..b2aeeb0d8 100644
> --- a/perl/Makefile
> +++ b/perl/Makefile
> @@ -1,6 +1,22 @@
>  #
>  # Makefile for perl support modules and routine
>  #
> +# This Makefile generates "perl.mak", which contains the actual build and
> +# installation directions.
> +#
> +# PERL_PATH must be defined to be the path of the Perl interpreter to use.
> +#
> +# prefix must be defined as the Git installation prefix.
> +#
> +# localedir must be defined as the path to the locale data.
> +#
> +# perllibdir may be optionally defined to override the default Perl module
> +# installation directory, which is relative to prefix. If perllibdir is not
> +# absolute, it will be treated as relative to prefix.
> +#
> +# NO_PERL_MAKEMAKER may be defined to use a built-in Makefile generation method
> +# instead of Perl MakeMaker.
> +
>  makfile:=perl.mak
>  modules =
>
> @@ -12,6 +28,16 @@ ifndef V
>  	QUIET = @
>  endif
>
> +# If a library directory is provided, and it is not an absolute path, resolve
> +# it relative to prefix.
> +ifneq ($(perllibdir),)
> +ifneq ($(filter /%,$(firstword $(perllibdir))),)
> +perllib_instdir = $(perllibdir)
> +else
> +perllib_instdir = $(prefix)/$(perllibdir)
> +endif
> +endif

>  all install instlibdir: $(makfile)
>  	$(QUIET)$(MAKE) -f $(makfile) $@
>
> @@ -25,7 +51,12 @@ clean:
>  $(makfile): PM.stamp
>
>  ifdef NO_PERL_MAKEMAKER
> -instdir_SQ = $(subst ','\'',$(prefix)/lib)
> +
> +ifeq ($(perllib_instdir),)
> +perllib_instdir = $(prefix)/lib
> +endif
> +
> +instdir_SQ = $(subst ','\'',$(perllib_instdir))
>
>  modules += Git
>  modules += Git/I18N
> @@ -42,7 +73,7 @@ modules += Git/SVN/Prompt
>  modules += Git/SVN/Ra
>  modules += Git/SVN/Utils
>
> -$(makfile): ../GIT-CFLAGS Makefile
> +$(makfile): ../GIT-CFLAGS ../GIT-PERL-DEFINES Makefile
>  	echo all: private-Error.pm Git.pm Git/I18N.pm > $@
>  	set -e; \
>  	for i in $(modules); \
> @@ -79,12 +110,21 @@ $(makfile): ../GIT-CFLAGS Makefile
>  	echo '	cp private-Error.pm "$$(DESTDIR)$(instdir_SQ)/Error.pm"' >> $@
>  	echo instlibdir: >> $@
>  	echo '	echo $(instdir_SQ)' >> $@
> +
>  else
> -$(makfile): Makefile.PL ../GIT-CFLAGS
> -	$(PERL_PATH) $< PREFIX='$(prefix_SQ)' INSTALL_BASE='' --localedir='$(localedir_SQ)'
> +
> +# This may be empty if perllibdir was empty.
> +instdir_SQ = $(subst ','\'',$(perllib_instdir))
> +
> +$(makfile): Makefile.PL ../GIT-CFLAGS ../GIT-PERL-DEFINES
> +	$(PERL_PATH) $< \
> +	  PREFIX='$(prefix_SQ)' INSTALL_BASE='' \
> +	  LIB='$(instdir_SQ)' \
> +	  --localedir='$(localedir_SQ)'
> +
>  endif
>
>  # this is just added comfort for calling make directly in perl dir
>  # (even though GIT-CFLAGS aren't used yet. If ever)
> -../GIT-CFLAGS:
> -	$(MAKE) -C .. GIT-CFLAGS
> +../GIT-CFLAGS ../GIT-PERL-DEFINES:
> +	$(MAKE) -C .. $(@F)