Stdlib: str_increment()/str_decrement() phantom — function_exists true on PHP 8.2 reference (ext/standard/string.c, re-#11842)

[PurHur]

Category

stdlib · php-src-strict

Problem

PHP 8.3+ str_increment() / str_decrement() must be absent from function_exists() and get_defined_functions()['internal'] on the default PHP 8.2 reference profile (Zend 8.2 in Docker). The VM advertises both on the 8.4.0-dev line via CompilerVersion::supportsStrIncrement() / advertisesBuiltinSince('8.3.0'), diverging from php-src-strict reference behavior (same class of bug fixed for zend_thread_id() in #11842).

Repro	Zend 8.2 (2026-07-05)	VM (2026-07-05)
function_exists('str_increment')	false	true
in_array('str_increment', get_defined_functions()['internal'])	false	true

Callable under forward profile (PHP_COMPILER_PROFILE=8.3 / stable 8.4+) is fine once advertisement matches Zend for that profile.

php-src reference

• php/php-src ext/standard/string.c — PHP_FUNCTION(str_increment), PHP_FUNCTION(str_decrement) (PHP 8.3)
• php/php-src Zend/zend_API.c — conditional function registration by PHP version

PHP implementation target

• lib/CompilerVersion.php — split callable gate (supportsStrIncrement()) from advertisement gate (advertisesStrIncrement() mirroring advertisesMbStrPad() / Stdlib: PHP 8.4 forward-profile gated builtins — function_exists/extension_loaded true on reference profile (ext/standard) #16086)
• ext/standard/Module.php + function_exists lowering — register/c advertise only when profile ≥ 8.3.0 stable or explicit forward profile
• script/capability-matrix.php notes if matrix rows change

Repro

./script/docker-exec.sh -- bash -lc 'php test/repro/maintainer_gap_str_increment_phantom_function_exists.php; echo exit:$?'
./script/docker-exec.sh -- bash -lc 'php bin/vm.php test/repro/maintainer_gap_str_increment_phantom_function_exists.php; echo exit:$?'

Done when

• Repro ok on VM with default/php-src reference profile (8.2)
• function_exists / get_defined_functions true when PHP_COMPILER_PROFILE=8.3+ or stable 8.4 runtime
• Compliance guard under test/compliance/cases/string/
• php-src-strict; no php-compiler-strict shortcut

[PurHur]

claim: PHP Compiler STD Lib — starting this run

[PurHur]

Merged via #16297.

Fix: Split supportsStrIncrement() (registration / forward PHP_COMPILER_PROFILE=8.3+) from advertisesStrIncrement() (function_exists gate). Wired through BuiltinIntrospectionPolicy — default 8.4.0-dev reference now matches Zend 8.2 (no phantom).

Verification:

• php bin/vm.php test/repro/maintainer_gap_str_increment_phantom_function_exists.php → ok
• VM compliance: str_increment_phantom.phpt, php84_math_string_builtins_phantom.phpt green
• Forward profile: PHP_COMPILER_PROFILE=8.3 php bin/vm.php test/compliance/cases/stdlib/forward_profile_builtins.phpt → si=yes, str_increment('a') → b