Subject: Re: [PATCH ab/simplify-perl-makefile] perl: treat PERLLIB_EXTRA as an extra path again (Re: [PATCH v6] Makefile: replace perl/Makefile.PL with simple make rules)

From: Ævar Arnfjörð Bjarmason <[email-masked]>
Date: Tue, 02 Jan 2018 21:39:28 +0100

On Tue, Jan 02 2018, Jonathan Nieder jotted:

> Subject: perl: treat PERLLIB_EXTRA as an extra path again
>
> PERLLIB_EXTRA was introduced in v1.9-rc0~88^2 (2013-11-15) as a way
> for packagers to add additional directories such as the location of
> Subversion's perl bindings to Git's perl path.  Since 20d2a30f
> (Makefile: replace perl/Makefile.PL with simple make rules,
> 2012-12-10) setting that variable breaks perl-based commands instead:
>
>  $ PATH=$HOME/opt/git/bin:$PATH
>  $ make install prefix=$HOME/opt/git PERLLIB_EXTRA=anextralibdir
> [...]
>  $ head -2 $HOME/opt/git/libexec/git-core/git-add--interactive
>  #!/usr/bin/perl
>  use lib (split(/:/, $ENV{GITPERLLIB} || ":helloiamanextrainstlibdir" || "/usr/local/google/home/jrn/opt/git/share/perl5"));
>  $ git add -p
>  Empty compile time value given to use lib at /home/jrn/opt/git/libexec/git-core/git-add--interactive line 2.
>
> Removing the spurious ":" at the beginning of ":$PERLLIB_EXTRA" avoids
> the "Empty compile time value" error but with that tweak the problem
> still remains: PERLLIB_EXTRA ends up replacing instead of
> supplementing the perllibdir that would be passed to 'use lib' if
> PERLLIB_EXTRA were not set.
>
> The intent was to simplify, as the commit message to 20d2a30f
> explains:
>
> | The scripts themselves will 'use lib' the target directory, but if
> | INSTLIBDIR is set it overrides it. It doesn't have to be this way,
> | it could be set in addition to INSTLIBDIR, but my reading of
> | [v1.9-rc0~88^2] is that this is the desired behavior.
>
> Restore the previous code structure to make PERLLIB_EXTRA work again.
>
> Reproducing this problem requires an invocation of "make install"
> instead of running bin-wrappers/git in place, since the latter sets
> the GITPERLLIB environment variable, avoiding trouble.
>
> Reported-by: Jonathan Koren <[email-masked]>
> Signed-off-by: Jonathan Nieder <[email-masked]>
> ---
> Jonathan Nieder wrote:
>> Hi,
>>
>> Ævar Arnfjörð Bjarmason wrote:
>>
>> > +++ b/Makefile
>> [...]
>> > -PERL_DEFINES = $(PERL_PATH_SQ):$(PERLLIB_EXTRA_SQ)
>> > -$(SCRIPT_PERL_GEN): % : %.perl perl/perl.mak GIT-PERL-DEFINES GIT-VERSION-FILE
>> > +PERL_DEFINES = $(PERL_PATH_SQ):$(PERLLIB_EXTRA_SQ):$(perllibdir_SQ)
>> > +$(SCRIPT_PERL_GEN): % : %.perl GIT-PERL-DEFINES GIT-VERSION-FILE
>> >  	$(QUIET_GEN)$(RM) $@ $@+ && \
>> > -	INSTLIBDIR=`MAKEFLAGS= $(MAKE) -C perl -s --no-print-directory instlibdir` && \
>> >  	INSTLIBDIR_EXTRA='$(PERLLIB_EXTRA_SQ)' && \
>> >  	INSTLIBDIR="$$INSTLIBDIR$${INSTLIBDIR_EXTRA:+:$$INSTLIBDIR_EXTRA}" && \
>> >  	sed -e '1{' \
>> >  	    -e '	s|#!.*perl|#!$(PERL_PATH_SQ)|' \
>> >  	    -e '	h' \
>> > -	    -e '	s=.*=use lib (split(/$(pathsep)/, $$ENV{GITPERLLIB} || "'"$$INSTLIBDIR"'"));=' \
>> > +	    -e '	s=.*=use lib (split(/$(pathsep)/, $$ENV{GITPERLLIB} || "'"$$INSTLIBDIR"'" || "'"$(perllibdir_SQ)"'"));=' \
>>
>> This appears to have broken a build with INSTLIBDIR set.
>
> Here it is in patch form.
>
>  Makefile | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/Makefile b/Makefile
> index 5c73cd208a..409e8f6ec9 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1951,12 +1951,13 @@ $(SCRIPT_PERL_GEN):
>  PERL_DEFINES = $(PERL_PATH_SQ):$(PERLLIB_EXTRA_SQ):$(perllibdir_SQ)
>  $(SCRIPT_PERL_GEN): % : %.perl GIT-PERL-DEFINES GIT-VERSION-FILE
>  	$(QUIET_GEN)$(RM) $@ $@+ && \
> +	INSTLIBDIR='$(perllibdir_SQ)' && \
>  	INSTLIBDIR_EXTRA='$(PERLLIB_EXTRA_SQ)' && \
>  	INSTLIBDIR="$$INSTLIBDIR$${INSTLIBDIR_EXTRA:+:$$INSTLIBDIR_EXTRA}" && \
>  	sed -e '1{' \
>  	    -e '	s|#!.*perl|#!$(PERL_PATH_SQ)|' \
>  	    -e '	h' \
> -	    -e '	s=.*=use lib (split(/$(pathsep)/, $$ENV{GITPERLLIB} || "'"$$INSTLIBDIR"'" || "'"$(perllibdir_SQ)"'"));=' \
> +	    -e '	s=.*=use lib (split(/$(pathsep)/, $$ENV{GITPERLLIB} || "'"$$INSTLIBDIR"'"));=' \
>  	    -e '	H' \
>  	    -e '	x' \
>  	    -e '}' \

This obviously makes perfect sense if the intent is to add this lib dir
instead of it being a replacement (as is clear from this being an issue
you're noting).

With the benefit of hindsight in re-reading the commit + this report I
can see that it *should* be that way, but I assumed it was the other way
around when I wrote this up.

Thanks!