Language: keyed list destructuring with spread — ['k' => $v, ...$tail] = (zend_compile.c)

[PurHur]

Category

language

Problem

Numeric list spread [$a, ...$rest] = $arr is VM-complete (#4835). Keyed list destructuring with a spread arm — e.g. ['label' => $label, ...$others] = $assoc — is not covered by compliance tests and may use the wrong tail offset: php-cfg spread lowering uses listSpreadFromIndex counting only positional slots, while Zend merges remaining elements after consuming keyed assignments.

Workers should not assume keyed+spread works because numeric spread PHPT passes.

php-src reference

• php/php-src Zend/zend_compile.c — zend_compile_list_assign keyed + unpack
• php/php-src Zend/zend_execute.c — list assign runtime

Repro

<?php
$src = ['label' => 'L', 'a' => 1, 'b' => 2];
['label' => $label, ...$rest] = $src;
ksort($rest);
var_export($label);
echo "\n";
var_export($rest);

php repro_keyed_list_spread.php
./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php repro_keyed_list_spread.php'

Record Zend output as authoritative; today VM may assign wrong keys into $rest or fail compile.

Stretch: string-key spread tail must still error when remainder is not a list (same as #4835).

Scope

Area	Files
php-cfg patch	script/apply-patches.sh — parseListAssignment spread index for keyed arms
Compiler	lib/Compiler.php — TYPE_LIST_SPREAD_ASSIGN offset semantics
VM	lib/VM.php — merge keyed slots then append list tail
Tests	test/compliance/cases/language/list_destructuring_keyed_spread.phpt
JIT	Follow #4885 after VM green

Done when

• Repro var_export output matches Zend on VM
• Compliance PHPT added; ci-fast --filter list_destructuring_keyed green
• Document interaction with Language: list destructuring spread — JIT/AOT TYPE_LIST_SPREAD_ASSIGN (phase 2 of #4835) #4885 (JIT spread) in PR

Links

• Language: list destructuring with spread — [$a, ...$rest] = $arr (zend_compile.c) #4835 numeric spread · Language: list destructuring spread — JIT/AOT TYPE_LIST_SPREAD_ASSIGN (phase 2 of #4835) #4885 JIT spread · Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492

[PurHur]

claim: cursor-agent-lane-c — starting this run

[PurHur]

Merged via #4896

Verification

• VM repro: ['label' => $label, ...$rest] = $src → 'L' + array('a'=>1,'b'=>2)
• ./vendor/bin/phpunit --filter list_destructuring_keyed_spread test/compliance/VMTest.php — OK (1 test)
• Related: list_destructuring_spread, keyed_list_destruct — OK (3 tests)

JIT spread for keyed tails tracked separately in #4885.