Re: [PATCH] global: resolve Perl executable via PATH

[Jeff King <peff@peff.net>]

On Wed, Apr 05, 2023 at 04:52:40PM +0200, Patrick Steinhardt wrote:

> > Is there a reason to not set PERL_PATH, which is the
> > documented method to handle this?  From the Makefike:
> > 
> > # Define PERL_PATH to the path of your Perl binary (usually /usr/bin/perl).
> 
> Setting PERL_PATH helps with a subset of invocations where the Makefile
> either executes Perl directly or where it writes the shebang itself. But
> the majority of scripts I'm touching have `#!/usr/bin/perl` as shebang,
> and that path is not adjusted by setting PERL_PATH.

Which scripts? If I do:

  mkdir /tmp/foo
  ln -s /usr/bin/perl /tmp/foo/my-perl
  make PERL_PATH=/tmp/foo/my-perl prefix=/tmp/foo install

  head -n 1 /tmp/foo/bin/git-cvsserver

Then I see:

  #!/tmp/foo/my-perl

And that is due to this segment in the Makefile:

  $(SCRIPT_PERL_GEN): % : %.perl GIT-PERL-DEFINES GIT-PERL-HEADER GIT-VERSION-FILE
          $(QUIET_GEN) \
          sed -e '1{' \
              -e '        s|#!.*perl|#!$(PERL_PATH_SQ)|' \
              -e '        r GIT-PERL-HEADER' \
              -e '        G' \
              -e '}' \
              -e 's/@@GIT_VERSION@@/$(GIT_VERSION)/g' \
              $< >$@+ && \
          chmod +x $@+ && \
          mv $@+ $@

And that behavior goes all the way back to bc6146d2abc ('build' scripts
before installing., 2005-09-08). If there are some perl scripts we are
"building" outside of this rule, then that is probably a bug.

The only thing I found via:

  find /tmp/foo -type | xargs grep /usr/bin/perl

was a sample hook (which is probably a bug; we do munge the hook scripts
to replace @PERL_PATH@, etc, but I think the Makefile never learned that
the template hook scripts might be something other than shell scripts).

-Peff