Stdlib: mb_str_pad() — multibyte string padding (ext/mbstring/mbstring.c parity)

[PurHur]

Category

stdlib · php-src-strict · spec refresh 2026-06-19

Problem

mb_str_pad() (PHP 8.3+) pads a multibyte string to a target display width. VM landed via #6081 (ext/mbstring/mb_str_pad.php, VmMbstring::mb_str_pad()), but this tracker stays open for remaining Zend gaps:

1. JIT/AOT — JitMbStrPad.php still uses in-module LLVM width logic instead of PHP SSOT (see php-in-php: ext/bcmath AOT lowering — share VmBcmath PHP path, unblock native self-host (ext/bcmath) #6100-style audit)
2. Enum/object operands — must TypeError under php-src-strict (mirror mb_strlen guards)
3. Capability matrix — ensure docs/capabilities.md notes JIT PHPT when green

Bundled duplicate: #6081 also tracks grapheme_strimwidth() (#9793); this issue is the mb_str_pad-only slice.

php-src reference

• php/php-src ext/mbstring/mbstring.c — PHP_FUNCTION(mb_str_pad)
• php/php-src ext/mbstring/mbstring.stub.php

Repro (VM OK; enum gap)

<?php
var_dump(function_exists('mb_str_pad')); // true on VM (2026-06-19)
echo mb_str_pad('あ', 4, 'x'), "\n";   // あxxx

enum E: string { case A = 'a'; }
try {
    mb_str_pad(E::A, 5);
    echo "enum FAIL\n";
} catch (Throwable $e) {
    echo get_class($e), ': ', $e->getMessage(), "\n";
}

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php bin/vm.php test/repro/maintainer_mb_str_pad.php
php bin/jit.php test/repro/maintainer_mb_str_pad.php
'

Scope

Path	Work
ext/mbstring/mb_str_pad.php	✅ VM builtin landed
ext/mbstring/VmMbstring.php	Enum TypeError guards
ext/mbstring/JitMbStrPad.php	Route through PHP helper or document VM-only
test/compliance/cases/stdlib/mb_str_pad*.phpt	STR_PAD_* + enum operand

Done when

• Enum case operand repro throws TypeError on VM/JIT/AOT (php-src-strict)
• JIT repro matches VM for width/STR_PAD_* table
• ./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && vendor/bin/phpunit --filter mb_str_pad' green
• php script/capability-matrix.php reflects JIT/AOT notes

Related

• Stdlib: grapheme_strimwidth() / mb_str_pad() — PHP 8.4 string helpers missing (ext/intl, ext/mbstring) #6081, Stdlib: grapheme_strimwidth() missing — PHP 8.4 intl width trim (ext/intl/grapheme_string.c) #9793, Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492

[PurHur]

claim: PHP Compiler STD Lib Advanced — batch (DOM managed-property fetch #14419 follow-up, #9793, #4006)

[PurHur]

Merged VM/JIT/enum slice via #15926 — supportsMbStrPad() now honors PHP_COMPILER_PROFILE=8.3/8.4. AOT LLVM verify in JitMbStrPad remains open on #4006 JIT slice.