perl: ship a usable core-module runtime (generated files + static XS) so File::Spec/POSIX load on Kandelo

[brandonpayton]

Purpose

The Perl Homebrew bottle shipped only perl.wasm with no core-module runtime,
and the interpreter crashed on any real module load — so the port only ever
passed a trivial arithmetic smoke. This makes Perl-on-Kandelo actually usable:
File::Spec, POSIX, Cwd, XSLoader, Config and the pure-perl core all
load and run. Fixes kd-k7zy (follow-up from the kd-p3hr language-runtime wave,
where File::Spec failed because generated runtime files such as XSLoader.pm
were never staged).

Root causes fixed

1. Generated runtime files were never produced or packaged. build-perl.sh
   ran make perl, which stops before perl-cross's nonxs_ext/extensions
   targets that generate lib/XSLoader.pm (from dist/XSLoader/XSLoader_pm.PL)
   and stage the core-module tree via pm_to_blib. Compounding it, the target
   Config had an empty osname, so ExtUtils::MakeMaker's $Config{osname} eq … probes hit undef and every module's staging failed. Fix:
   -Dosname=linux (Kandelo is a POSIX/linux-like syscall surface) + build with
   make -k, then package lib/perl5/5.40.3 as a new perl-runtime.zip output.

2. The shipped interpreter miscompiled and panicked on any weak-ref use.
   build-perl.sh already documents -fno-strict-aliasing as load-bearing
   (clang -O2 miscompiles perl's weak-ref machinery into a magic_killbackrefs
   panic) but applied it only to HOSTCFLAGS (host miniperl), not the target
   -Dccflags. So perl.wasm panicked magic_killbackrefs/del_backref the
   moment any module traversed weak refs (use File::Spec, use Config). Fix:
   add -fno-strict-aliasing to the target ccflags.

3. XS core modules could not load. The config shipped usedl=define; XS
   modules built .sos loaded via dlopen, which Kandelo's wasm musl does not
   implement (dlerror() not implemented). So File::Spec (→ File::Spec::Unix
   → Cwd, an XS module), POSIX, Fcntl, List::Util all failed. Fix:
   -Uusedl builds extensions statically, linking their XS into perl.wasm with
   a boot table so XSLoader::load resolves them without dlopen. perl-cross
   ignores -Dnoextensions, so the statically-linked set is curated by editing
   Makefile.config's fullpath_static_ext — dropping ext/re (recompiles
   regcomp.c → duplicate symbols vs core regcomp.o) and extensions needing
   libraries absent from the wasm sysroot / threads.

Changes

• packages/registry/perl/build-perl.sh — resolver-contract output handling
  (WASM_POSIX_DEP_OUT_DIR, sdk/activate.sh); -Dosname=linux;
  -fno-strict-aliasing on target ccflags; -Uusedl + curated
  fullpath_static_ext; make -k staging + perl-runtime.zip packaging with a
  post-check that the generated files (XSLoader.pm, Config.pm, File/Spec.pm,
  File/Spec/Unix.pm, Cwd.pm) are present.
• packages/registry/perl/package.toml — declare the perl-runtime output.
• packages/registry/perl/build.toml — revision 1 → 2 (output bytes change).
• homebrew/kandelo-homebrew/Formula/perl.rb — install perl.wasm + unzip the
  runtime into lib/perl5/5.40.3; test covers File::Spec, POSIX (a module
  that bootstraps via XSLoader), and XSLoader. (Requires the tap's
  formula_support/kandelo_package.rb; bottle-test acceptance tracks kd-yuef.)
• packages/registry/perl/demo/runtime-smoke.ts — Node kernel-host smoke.

Verification

Node runCentralizedProgram (host-fs passthrough, LC_ALL=C,
PERL5LIB=staged privlib) against the built perl.wasm (~4.2M static):

RESULTS=Config=ok,XSLoader=ok,FileSpec_catfile=ok,FileSpec_rel2abs=ok,Cwd_xs=ok,POSIX_xs=ok,Fcntl_xs=ok,ListUtil_xs=ok,DataDumper_xs=ok → PERL_RUNTIME_SMOKE_PASS

• File::Spec->catfile('a','b','c.txt') → a/b/c.txt
• File::Spec->rel2abs('x','/root') → /root/x (Cwd's XS bootstraps via XSLoader)
• POSIX::floor(3.7) → 3; Fcntl O_RDONLY; List::Util::sum(1..4) → 10; Cwd::getcwd
• Data::Dumper; XSLoader 0.32; Config version 5.40.3

perl.wasm ≈ 4.2M (static XS); perl-runtime.zip ≈ 10M (711 core .pm incl unicore).

Full gate (cargo test -p kandelo … --lib, vitest, libc/posix suites,
check-abi-version) was not run: this change is package-recipe only (build script,
manifest, formula, demo) and touches no kernel/host/ABI code. Browser bottle run
tracks kd-yuef.

Known boundaries (follow-ups filed)

• kd-dvph — perl 5.40 panics at startup parsing Kandelo musl's composite
  default locale (C.UTF-8;C;C;C;C;C); tests/smoke set LC_ALL=C.
• kd-gtxa — Errno_pm.PL finds no errno constants under the wasm sysroot, so
  Errno.pm is absent (make -k keeps going past it).
• kd-14n8 — broaden the static XS set (Encode/Compress/Sys::Syslog/re) by
  wiring the needed libs into the sysroot or implementing a working wasm dlopen.

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