Stdlib: extension_loaded('gd') true — imagecreate() stub without ext/gd (ext/gd/gd.c) #11675

Summary

extension_loaded('gd') returns true and function_exists('imagecreate') is true on VM while Zend (no ext/gd) reports both false. Calling imagecreate() throws Error — a phantom extension probe that misleads feature detection.

Mirrors #11669 / #11654 curl registry mismatches: skeleton ext/gd/Module.php registers as a full extension before libgd parity (#3496, #7407).

php-src reference

• php/php-src ext/gd/gd.c — module init + imagecreate
• php/php-src ext/standard/info.c — extension_loaded / get_loaded_extensions

Repro

test/repro/maintainer_gap_extension_loaded_gd_phantom.php

./script/docker-exec.sh -- bash -lc 'php test/repro/maintainer_gap_extension_loaded_gd_phantom.php; php bin/vm.php test/repro/maintainer_gap_extension_loaded_gd_phantom.php'

Zend: loaded=no, imagecreate=no, probe=absent

VM: loaded=yes, imagecreate=yes, probe=Error

Expected (php-src-strict)

Until ext/gd is fully implemented, extension_loaded('gd'), function_exists('imagecreate'), and defined('IMG_*') must all agree (absent/false). Follow curl deferral pattern: register under standard or withhold module until #3496 ships.

Implementation hints

• ext/gd/Module.php — getExtensionName(): 'standard' until real gd (Stdlib: extension_loaded('curl') true but curl_init() LogicException — phantom ext registration (ext/standard/info.c) #11627 pattern)
• Withhold imagecreate stubs from builtin table until extension probe is true
• PHP-in-PHP in ext/gd/; no new C runtime

Done when

• Repro matches Zend probe output on VM
• No extension_loaded('gd') true while image functions unavailable