Basic PIE downloader flag --with-pie

[asgrim]

Adds --with-pie (or --with-pie=/pie/path) options to ./configure; this downloads PIE into the given path (defaults to $$prefix/lib/php/pie).

Fixes php/pie#564

[asgrim]

General question to reviewers; what is the earliest version of PHP we could get this into? PIE supports PHP 8.1+, so ideally that, but obviously it is out of support, so won't actually get any new releases. I suppose it would be PHP 8.4+?

[henderkes]

While I'm all in for shipping pie with installations by default, I don't think build time is the place to start a download of a separate project. This seems more of a distribution issue than being related to php itself.

Also a bit weird to depend on pie, which has php as a dependency, when building php. Especially in versions that can't even run the phar.

[asgrim]

While I'm all in for shipping pie with installations by default, I don't think build time is the place to start a download of a separate project. This seems more of a distribution issue than being related to php itself.

This approach is the same already taken by PEAR, so there's already a precedence for this. Note that this isn't (yet) bundled by default, you must specify --with-pie to actually get this target to do its thing. There is a slight ulterior motive here; Docker's PHP images seem unwilling to ship PIE with their images unless PIE is bundled with PHP (like PEAR/PECL was); so I'm trying to take steps towards fulfilling that goal.

Also a bit weird to depend on pie, which has php as a dependency, when building php.

This target happens after PHP is already built :)

Especially in versions that can't even run the phar.

This is actually an interesting issue; I already encountered this since PIE does not advertise compatibility with PHP 8.6 yet. The built in Box "requirements checker" will cause the pie --version to fail; I'm wondering if we can handle this a bit more gracefully, but I'm not sure if it should non-zero the whole install, or still exit 0 just with a warning that we couldn't install PIE automatically or something.

[henderkes]

This approach is the same already taken by PEAR, so there's already a precedence for this.

Doesn't necessarily means it was or is the right decision :P

Docker's PHP images seem unwilling to ship PIE with their images unless PIE is bundled with PHP (like PEAR/PECL was);

Ah... yeah. That makes this make more sense. But I don't necessarily think it's necessary. The extension installer isn't currently bundled either, right?

COPY --from php/pie:latest /usr/local/bin/pie /usr/local/bin/pie
-> pie install imagick

should be acceptable.

And it won't have any issues in regards to old/new php versions because it could use a boxed binary.