Self-host M2: php-cfg UnionType parser — compiler_lib_spine_smoke compile fails

[PurHur]

Problem

BOOTSTRAP_LIB_SPINE_SMOKE=1 make bootstrap-selfhost-lib-spine-smoke is red on master (Docker php-compiler:22.04-dev, May 2026):

PHP Fatal error: Uncaught LogicException: Unknown type node: UnionType
  in vendor/ircmaxell/php-cfg/lib/PHPCfg/Parser.php:206
  … Runtime->parse() → bin/compile.php during spine bundle compile

php bin/compile.php -l test/selfhost/compiler_lib_spine_smoke/main.php fails with the same error.

Docs still claim M2 native link ✅ (docs/self-host-target.md, docs/bootstrap-selfhost.md). make bootstrap-loop-probe --dry-run fails at the M2 prerequisite step.

We already ship patches/php-cfg-intersection-type.patch for IntersectionType; union return/parameter types are not parsed.

First offender (spine bundle)

File	Symbol	Syntax
ext/standard/VmString.php	VmString::str_word_count	): int|array (line ~1931)

Audit other inventory paths after the patch lands (grep -E '\): [A-Za-z_\\]+\|' ext/ lib/).

Goal

Spine bundle compiles and links natively without Zend:

BOOTSTRAP_LIB_SPINE_SMOKE=1 make bootstrap-selfhost-lib-spine-smoke
# stdout: compiler_lib_spine_smoke bundle OK
./script/bootstrap-loop-probe.sh --dry-run   # M2 step passes

Implementation hints

Piece	Path	Notes
Vendor patch	patches/php-cfg-union-type.patch	Mirror php-cfg-intersection-type.patch: Op\Type\Union, parseTypeNode() for Node\UnionType
Apply	script/apply-patches.sh	Composer patches entry if needed
CFG types	lib/Compiler.php / lib/JIT.php	Only if lowering gaps appear after parse (separate PR)
Spine	test/selfhost/compiler_lib_spine_smoke/main.php	No shim removal required for this slice

Done when

• BOOTSTRAP_LIB_SPINE_SMOKE=1 make bootstrap-selfhost-lib-spine-smoke exits 0 on harness
• php bin/compile.php -l test/selfhost/compiler_lib_spine_smoke/main.php exits 0
• docs/bootstrap-selfhost.md M2 row matches reality (no false green)
• Epic Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492 / ROADMAP 🗺️ ROADMAP: Self-host + web-capable PHP subset (living) #78 M2 status updated

Repro (local / Docker only)

script/apply-patches.sh
./script/docker-exec.sh -- bash -lc 'BOOTSTRAP_LIB_SPINE_SMOKE=1 make bootstrap-selfhost-lib-spine-smoke'

No GitHub Actions (#394 ✅).

Dependencies / links

• Blocks Self-host M2: native-link bin/vm.php + lib/AOT/Linker.php in spine smoke #2134 (bin/vm.php promotion), Self-host M2: BootstrapVmDriver native execute smoke (post-#2134 bin/vm.php link) #2201 VM driver execute, M4: Bootstrap loop — native binary rebuilds next compiler revision #1498 / Self-host M4: Native gen-2 AOT emit without Zend fallback (post-#1498) #2075 M4 loop
• Parallel: Self-host M3: native emit-TU binaries run without startup crash #2442 M3 emit-TU (orthogonal)
• Epic Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492 · Dependencies: php-parser token map for PHP 8.2+ host runs #113 host parser token map (orthogonal)

[PurHur]

Verified green on harness after #2502–#2504 land:

script/apply-patches.sh
php bin/compile.php -l test/selfhost/compiler_lib_spine_smoke/main.php  # exit 0
BOOTSTRAP_LIB_SPINE_SMOKE=1 make bootstrap-selfhost-lib-spine-smoke       # bundle OK

#2134 updated — next M2 work is bin/vm.php promotion only.