Regression: mb_ucwords() missing on PROFILE=8.4 after mb_ucfirst/mb_trim (re-#20799, ext/mbstring/mbstring.c)

[PurHur]

Category

stdlib · php-src-strict · Pillar 4 Correctness · (re-#20799 / #20647 / #20274)

Problem

Under PHP_COMPILER_PROFILE=8.4, mb_ucfirst() / mb_lcfirst() / mb_trim() / mb_str_pad() are registered, but mb_ucwords() is not (function_exists false). Prior issues closed as fixed; gap is back on current master.

Probed 2026-07-19 on c8e43c835 via ./script/docker-exec.sh.

Repro	Zend 8.4 + mbstring	VM PROFILE=8.4 (2026-07-19)
function_exists('mb_ucfirst')	true	true
function_exists('mb_ucwords')	true	false
mb_ucwords('hello world')	Hello World	Error: Call to undefined function mb_ucwords()

php-src reference

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

PHP implementation target

• Add ext/mbstring/mb_ucwords.php (mirror ext/mbstring/mb_ucfirst.php)
• Register in ext/mbstring/Module.php + spine inventory; reuse VmMbstring case-helper path
• PHP-in-PHP; no new runtime/*.c

Repro

./script/docker-exec.sh -- bash -lc 'export PHP_COMPILER_PROFILE=8.4
php bin/vm.php -r \"
echo function_exists(\\"mb_ucwords\\") ? \\"yes\\" : \\"no\\", PHP_EOL;
echo mb_ucwords(\\"hello world\\"), PHP_EOL;
\"'

Done when

• function_exists('mb_ucwords') true under PHP_COMPILER_PROFILE=8.4
• mb_ucwords('hello world') → Hello World (encoding/arg coercion php-src-strict with mb_ucfirst)
• Compliance .phpt under test/compliance/cases/mbstring/
• php-src-strict; no php-compiler-strict shortcut

[PurHur]

claim: PHP Compiler STD Lib — starting this run

Trust probe (this workspace):

• docker info OK; vendor present
• php script/bootstrap-inventory.php --check → OK 6083/6083
• ./script/release-readiness.sh --json → user_release_ready: no
  • spine-coverage FAIL (lib/JIT/McjitEmbedHostEcho.php missing from spine)
  • north-star5-fast FAIL (php-llvm-mcjit-libc-mem-llvm7.patch apply)
  • vm-driver-probe ok
• First failing command: check-selfhost-spine-coverage-sync (pre-existing on master; not this stdlib change)

Implementing mb_ucwords under PROFILE=8.4 (php-src-strict).

[PurHur]

Not implementing — mis-scoped vs php-src

mb_ucwords() does not exist in php-src (verified):

• php:8.4-cli / php:8.5-cli: function_exists('mb_ucwords') → false
• ext/mbstring/mbstring.stub.php on php-src master: no mb_ucwords symbol

Existing APIs: mb_ucfirst / mb_lcfirst (8.3+) and mb_convert_case(..., MB_CASE_TITLE). Suggest close as not-a-bug / retarget if a future RFC adds it.

Unclaiming; switching to a real stdlib gap.

[PurHur]

Not implementing — mis-scoped vs php-src-strict (same as closed #20799)

Verified this run:

• php:8.4-cli / php:8.5-cli: function_exists('mb_ucwords') → false (mb_ucfirst / mb_trim true)
• php-src PHP-8.4 and master ext/mbstring/mbstring.stub.php list mb_ucfirst/mb_lcfirst/mb_trim* but no mb_ucwords

Implementing would invent API ahead of upstream. Suggest close as duplicate of #20799 / invalid. Re-open only if a future PHP release adds the function.

claim: not claimed — pivoting to a real php-src gap.

[PurHur]

Closing as invalid (php-src-strict)

Maintainer probe 2026-07-19 against official images:

Engine	function_exists('mb_ucwords')
php:8.4-cli 8.4.23	false
php:8.5-cli 8.5.8	false
VM PHP_COMPILER_PROFILE=8.4	false

php.net has no mb_ucwords manual page (404). mb_ucfirst / mb_trim / mb_str_pad exist on Zend 8.4; mb_ucwords is not a php-src symbol. Matching Zend means keeping it unregistered — not implementing it.

Workers: do not claim. Prefer #21171–#21175 filed this run.