Bootstrap: php-cfg list-spread overlay missing — Undefined property Assign::$listSpreadRhs warnings (zend_compile.c)

[PurHur]

Category

bootstrap | language

Problem

When patches/php-cfg-list-spread.patch (overlay via script/apply-patches.sh) is not applied, every assignment through PHPCfg Op\Expr\Assign emits PHP warnings:

Undefined property: PHPCfg\Op\Expr\Assign::$listSpreadRhs in lib/Compiler.php

List destructuring with spread (#4835, #4889) was implemented assuming the overlay property exists. lib/Compiler.php reads $op->listSpreadRhs at lines ~1238, ~1381, ~4250, ~4254 without guarding property_exists().

Workers see noisy logs on any script; bootstrap/self-host compiles are especially noisy (dozens of warnings per file).

php-src reference

• php/php-src Zend/zend_compile.c — list destructuring spread lowering
• Overlay: patches/php-cfg-list-spread.patch (apply_php_cfg_list_spread_overlay() in script/apply-patches.sh)

Repro (verified 2026-06-04)

A — warning count on trivial assign

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
cd /compiler
php bin/vm.php -r "\$a=1;" 2>&1 | grep -c listSpreadRhs || echo 0
'

Patch state	grep -c listSpreadRhs on \$a=1;
After ./script/apply-patches.sh	0
Fresh composer install without overlay	≥4 (multiple compile paths)

B — list spread still compiles when patch applied

<?php
[$a, ...$rest] = [1, 2, 3];
var_export([$a, $rest]);

Scope (this repo)

Module	Path
Compiler	lib/Compiler.php — property_exists($op, 'listSpreadRhs') before all reads
Bootstrap	Ensure script/apply-patches.sh runs in Docker CI / composer install post-step (document if missing)
Tests	test/unit/ or compliance: compile \$a=1; captures stderr without listSpreadRhs

Do not add C runtime logic; patch overlay or PHP guard only.

Done when

• Repro A returns 0 warnings with and without vendor patch (guard path)
• Repro B list-spread still lowers correctly when patch is applied
• php script/bootstrap-inventory.php --check / self-host compile of lib/Compiler.php no longer spams warnings
• ./script/ci-fast.sh --filter Compiler or targeted unit green

Verification

./script/apply-patches.sh
./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php -r "\$a=1;" 2>&1 | grep listSpreadRhs && exit 1 || exit 0'
make bootstrap-selfhost-link  # no listSpreadRhs noise in log

Related

• Language: list destructuring with spread — [$a, ...$rest] = $arr (zend_compile.c) #4835, Language: keyed list destructuring with spread — ['k' => $v, ...$tail] = (zend_compile.c) #4889 list spread semantics
• Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492 self-host — clean compile logs matter for M3–M5

[PurHur]

claim: worker-lane-a — checked lane A queue; #4701 (language) claimed instead (lower eligible language issue).

[PurHur]

claim: worker-lane-a — starting this run

[PurHur]

Merged via #7577.

Status: Compiler guards were already in place (assignIsListSpread() uses property_exists() before all listSpreadRhs reads — landed in #5703/#6069). This PR adds the missing regression test for the guard path when the php-cfg overlay is absent.

Verification:

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php -r "\$a=1;" 2>&1 | grep listSpreadRhs && exit 1 || exit 0'
# exit 0

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && vendor/bin/phpunit --filter ListSpreadRhsCompileTest'
# OK (4 tests, 8 assertions)