Regression: PHP 8.4 builtins advertised via function_exists on 8.2 reference profile (re-#16292, ext/standard)

[PurHur]

Category

stdlib · php-src-strict · version-gate regression

Problem

On the default PHP 8.2 reference profile, function_exists() must be false for PHP 8.4-only symbols. This compiler returns true for several gated builtins Zend does not expose.

Symbol	Zend 8.2+	VM (2026-07-05)
str_increment	false	true
str_decrement	false	true
zend_thread_id	false	true
readonly	false	true

php-src reference

• php/php-src ext/standard/basic_functions.c — registration gated by PHP_VERSION_ID
• php/php-src ext/standard/string.c — str_increment/str_decrement

PHP implementation target

• lib/CompilerVersion.php + ext/standard/BuiltinIntrospectionPolicy.php — align function_exists() advertisement with supports*() gates (re-Stdlib: PHP 8.4 forward-profile gated builtins — function_exists/extension_loaded true on reference profile (ext/standard) #16086, Stdlib: str_increment/str_decrement/fpow phantom on 8.2 reference (ext/standard/string.c, math.c) #11846, Stdlib: str_increment()/str_decrement() phantom — function_exists true on PHP 8.2 reference (ext/standard/string.c, re-#11842) #16292)

Repro

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

Done when

• All four symbols false on 8.2 reference profile (still callable only when profile/version gate allows)
• Unit guard in CompilerVersionBuiltinAdvertisementTest or equivalent
• php-src-strict

[PurHur]

claim: cursor-agent-lane-b — starting this run

[PurHur]

Merged via #16362.

Fix: Added advertisesZendThreadId() / advertisesReadonlyBuiltin() (stable 8.4.0+ only) and wired BuiltinIntrospectionPolicy so function_exists() matches Zend 8.2 reference for all four symbols (str_increment, str_decrement, zend_thread_id, readonly). Forward profile keeps callability while introspection stays withheld until stable 8.4.

Verification:

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php bin/vm.php test/repro/maintainer_gap_profile_phantom_function_exists.php  # ok
./vendor/bin/phpunit --filter "CompilerVersionBuiltinAdvertisementTest|ForwardProfilePhantomIntrospectionTest"  # OK (69 tests)
'