Regression: AOT str_pad() drops pad string — prints "a" not "a...." (re-#23911, ext/standard/string.c)

Problem

str_pad() matches Zend on VM, but AOT returns the input unmodified (padding ignored). Prior AOT segfault (#23911) was closed; current symptom is silent wrong output.

Repro	Zend / VM (2026-08-02, `79a0e27de`)	AOT after `bin/compile.php`
`str_pad(\"a\", 5, \".\")`	`a....`	`a`

Reflection-only sibling: #25045 (not this AOT behavior gap).

php-src reference

php/php-src ext/standard/string.c — PHP_FUNCTION(str_pad)
php/php-src ext/standard/basic_functions.stub.php — str_pad

PHP implementation target

AOT/JIT path for str_pad in ext/standard + lib/JIT — PHP-in-PHP; pad length / pad_string assembly under thin standalone Runtime
Re-verify three-arg and STR_PAD_* variants; no new C in runtime/

Repro

./script/docker-exec.sh -- bash -lc '
cat > /tmp/aot_str_pad.php <<'"'"'PHP'"'"'
<?php
echo str_pad("a", 5, "."), "\n";
PHP
echo -n "zend="; php /tmp/aot_str_pad.php
echo -n "vm="; php bin/vm.php /tmp/aot_str_pad.php 2>/dev/null
php bin/compile.php -o /tmp/aot_str_pad /tmp/aot_str_pad.php && /tmp/aot_str_pad
'

Done when

AOT binary prints a.... matching Zend/VM
Prefer --repeat 10 on the built binary before claiming fixed
Compliance or test/repro/ guard
php-src-strict; no php-compiler-strict shortcut

claim: Lane B implementer (Composer) — starting this run

Mandatory pre-triage (this workspace):

docker info: ok
php script/bootstrap-inventory.php --check: OK 7109/7109
php script/check-selfhost-spine-coverage-sync.php: FAILED — 5 inventory files missing from spine (ext/imap/VmImapMutf7.php + 4 imap utf7/mutf7 helpers). Pillar 1 / north-star5-fast red until spine sync.
./script/release-readiness.sh --json: user_release_ready: no (first related fail: north-star5-fast → spine coverage sync)
gen0_provenance: fresh; vm-driver-probe / gen0-driver-functional: ok

Claiming #26995 (Lane B, area:compiler AOT wrong-output — not Reflection stub / not ext-owner lane). Will verify AOT str_pad("a", 5, ".") → a.... with --repeat 10.

Repro on current master (2115b36cad): already green — not the 2026-08-02 a wrong-output.

zend=a....
vm=a....
aot=a....

Also STR_PAD_LEFT / STR_PAD_BOTH / default pad, variable args, PHP_COMPILER_HELPER_RUNTIME_O=0, and --repeat 10 all match. Existing AOT fixtures str_pad.phpt + str_pad_literal_segfault.phpt pass.

Shipping a #26995-tagged guard (exact issue one-liner) and closing via PR — root cause was already addressed by the inline StrPadJitHelper path (#23911 / #23931); this filing was a silent-wrong-output recheck that now holds.

Closed — already fixed on master (verified this run on 2115b36cad).

Issue repro:

zend=a....
vm=a....
aot=a....

--repeat 10 all a....; also STR_PAD_*, variable pad_string, and PHP_COMPILER_HELPER_RUNTIME_O=0.

Root path: inline StrPadJitHelper / __compiler_str_pad (#23911 / #23931). Existing AOT guards test/fixtures/aot/cases/str_pad.phpt and str_pad_literal_segfault.phpt already cover three-arg padding.

Lane B next: claiming #27031 (AOT http_build_query segfault — confirmed red).

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Regression: AOT str_pad() drops pad string — prints "a" not "a...." (re-#23911, ext/standard/string.c) #26995

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Regression: AOT str_pad() drops pad string — prints "a" not "a...." (re-#23911, ext/standard/string.c) #26995

Description

Category

Problem

php-src reference

PHP implementation target

Repro

Done when

Activity

PurHur commented on Aug 6, 2026

PurHur commented on Aug 6, 2026

PurHur commented on Aug 6, 2026

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