Regression: ext/standard string builtins (null) coerce — Zend TypeError under PROFILE=8.4 (ext/standard/string.stub.php)

[PurHur]

Category

Stdlib · php-src-strict · PROFILE≥8.4 · sibling of #28686 (mbstring)

Problem

Under PHP_COMPILER_PROFILE=8.4, classic ext/standard string APIs still coerce null to "" (with E_DEPRECATED) instead of throwing TypeError like Zend/php-src 8.4 stubs (string not ?string).

Verified 2026-08-07 on master @45744edb07 (VM + JIT) inside ./script/docker-exec.sh. Host reference engine is 8.2 (deprecate+coerce); done-when is php-src 8.4 TypeError.

Call	Zend 8.4+	VM/JIT PROFILE=8.4 (2026-08-07)
str_contains(null, 'x')	TypeError	Deprecated + false
str_starts_with(null, 'x') / str_ends_with(null, 'x')	TypeError	Deprecated + coerce
trim/ltrim/rtrim(null)	TypeError	Deprecated + ''
strtolower/strtoupper/ucfirst/lcfirst/ucwords(null)	TypeError	Deprecated + ''
str_pad(null, n) / str_repeat(null, n) / strrev(null)	TypeError	Deprecated + coerce
strlen(null)	TypeError	Deprecated + 0
addslashes/stripslashes/htmlspecialchars/htmlentities/nl2br/wordwrap(null)	TypeError	Deprecated + ''
explode(',', null)	TypeError	Deprecated + ['']

php-src reference

• php/php-src ext/standard/string.stub.php — string parameters (not nullable) on listed APIs
• php/php-src ext/standard/string.c — ZPP string rejection of null since 8.1 deprecation → 8.4 TypeError

PHP implementation target

• Shared null→string builtin arg guards under PROFILE≥8.4 in ext/standard + VM/JIT (VmString::coerceStringBuiltinArg / JitStringBuiltinArg / TypeCheck) — not new C in runtime/
• Same fix pattern as Regression: mb_ucfirst/mb_trim/mb_str_pad(null) coerce — Zend TypeError under PROFILE=8.4 (re-#27941, ext/mbstring) #28686 for mbstring

Repro

./script/docker-exec.sh -- bash -lc 'PHP_COMPILER_PROFILE=8.4 php bin/vm.php /tmp/std_string_null84.php'
# also: PHP_COMPILER_PROFILE=8.4 php bin/jit.php /tmp/std_string_null84.php

<?php
error_reporting(E_ALL);
foreach (['trim', 'str_contains', 'htmlspecialchars', 'strlen', 'explode'] as $f) {
    try {
        $r = match ($f) {
            'str_contains' => str_contains(null, 'x'),
            'explode' => explode(',', null),
            'strlen' => strlen(null),
            default => $f(null),
        };
        echo "$f => ";
        var_export($r);
        echo "\n";
    } catch (Throwable $e) {
        echo "$f EX ", get_class($e), ':', $e->getMessage(), "\n";
    }
}

Done when

• Under PROFILE≥8.4, listed string APIs throw TypeError on null (VM + JIT; AOT if in scope) matching Zend 8.4
• Default/≤8.3 profile keeps Zend-compatible deprecate-or-coerce where php-src still does
• Compliance .phpt under test/compliance/cases/stdlib/ (or string/) asserting TypeError
• php-src-strict; no php-compiler-strict shortcut

[PurHur]

Maintainer gate probe (2026-08-07) @ 45744edb07

Posted here because #10533 comments are disabled (2500+ cap; same as #1492).

Gate	Status	Symptom
php script/bootstrap-inventory.php --check	green	OK 7209/7209 (optional doc drift: ClosureBindHelper.php method count)
./script/release-readiness.sh --json	red	user_release_ready: no
First failing command	check-selfhost-spine-coverage-sync	missing ext/dom/JitDomReplaceChildLiveSlots.php
north-star5-verify-fast	red	same spine gap
bootstrap-selfhost-vm-driver-execute-probe	green
bootstrap-gen0-driver-functional-smoke	green
gen-0 provenance	stale	7012b46bd + 34 lowering commits since

Pillar 1 blocker: spine include for JitDomReplaceChildLiveSlots.php — next php script/bootstrap-selfhost-next-includes.php --bundle=test/selfhost/compiler_lib_spine_smoke/main.php --limit=1.

Filed this run: #28689 (this), #28690, #28691, #28692. Open PR queue: 0. implementation-ready queue: stocked (200+).

[PurHur]

claim: PHP Compiler STD Lib — starting this run

Focus: PROFILE≥8.4 null→TypeError for ext/standard string builtins via shared VmString/JitStringBuiltinArg guards (php-src-strict; sibling pattern #28686).

[PurHur]

abandon: not a Zend 8.4 TypeError gap (php-src-strict)

Verified against the RFC + in-tree guards before implementing:

• RFC deprecate_null_to_scalar_internal_arg: DEP in 8.1+, TypeError in PHP 9.0 — not 8.4.
• Host/Zend 8.2 and the repo’s own soft-null path (VmString::coerceTrimFamilyStringArg / JitStringBuiltinArg::lowerTrimFamilyString, requiresForwardProfileStrictStringNull() === false) already match that: deprecate + coerce null → "".
• Many prior TypeError flips were reverted for exactly this reason (Regression: trim()/ltrim()/rtrim(null) TypeError under PROFILE=8.4 — Zend DEP+coerce (ext/standard/string.c) #21404, Regression: str_contains()/str_starts_with()/str_ends_with(null) TypeError under PROFILE=8.4 — Zend DEP+coerce (ext/standard/string.c, re-#20611) #21187, Regression: ucfirst()/lcfirst()/ucwords()/str_shuffle()/str_repeat(null) TypeError under PROFILE=8.4 — Zend DEP+coerce (re-#21428, ext/standard/string.c) #24598, Regression: mb_trim/mb_ucfirst/mb_lcfirst/mb_str_pad(null) TypeError under PROFILE=8.4 — Zend 8.4 DEP+coerce (ext/mbstring) #24176, …).

Suggest closing as not-a-bug / retarget to PROFILE≥9.0 when that forward profile exists. Not claiming further work here.

[PurHur]

Not a regression vs Zend — closing without code change.

Re-verified 2026-08-07 against php:8.4-cli (8.4.24): listed string args still deprecate + coerce null (soft-null). They do not throw TypeError.

Stub typed string ≠ ZPP TypeError on 8.4 — same finding as #28686 / #24176 / closed #28738/#28739. VM PROFILE=8.4 already matches Zend.

Gate for future filings: confirm against docker run --rm -i php:8.4-cli php, not stubs alone.