Language: #[AllowDynamicProperties] on parameter must compile-time fatal (zend_attributes.c)

[PurHur]

Category

language | php-src-strict

Problem

#[AllowDynamicProperties] is only valid on classes in PHP 8.2+. Zend rejects it on parameters with a compile-time fatal. This compiler accepts the attribute on a parameter (with spurious CFG deprecation noise) instead of failing like php-src.

Related umbrella: #4392 (attributes), #5124 (#[\DelayedTargetValidation]). This issue is the specific AllowDynamicProperties disallowed target slice — not promoted-parameter delayed validation (valid in PHP 8.4 via #5124).

php-src reference

• php/php-src Zend/zend_attributes.c — zend_validate_attribute_target(), allowed target bitmask
• php/php-src Zend/zend_compile.c — attribute attachment on zend_argument_info
• Builtin registration: php/php-src ext/standard/basic_functions.c / zend_attributes.stub.php — AllowDynamicProperties targets TARGET_CLASS only

Repro (failure today — probed 2026-06-07)

<?php
function f(#[AllowDynamicProperties] int $x) {}
echo "compiled\n";

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php -r "function f(#[AllowDynamicProperties] int \$x) {} echo \"compiled\";" 2>&1 | head -1
php bin/vm.php -r "function f(#[AllowDynamicProperties] int \$x) {} echo \"compiled\";" 2>&1
'

Runtime	Result
Zend PHP 8.2	Fatal error: Attribute "AllowDynamicProperties" cannot target parameter (allowed targets: class)
bin/vm.php	prints compiled (compile succeeds)

Additional invalid targets (same fix)

Snippet	Zend
#[AllowDynamicProperties] function g() {}	cannot target function
class C { #[AllowDynamicProperties] public int $p; }	cannot target property
const X = 1; #[AllowDynamicProperties] /* on const */	cannot target class constant

Add at least parameter + function cases to compliance PHPT.

Scope (this repo)

Layer	Path
Early guard	lib/Compiler/AttributeNames.php — assertAllowDynamicPropertiesClassTargetOnly() already called for some decls; extend to parameters and functions
Compile hook	lib/Compiler.php — parameter/method/function attribute validation passes (~lines calling AttributeNames::assertAllowDynamicPropertiesClassTargetOnly)
Builtin class	ext/standard/BuiltinAttributes.php — AllowDynamicProperties registered with TARGET_CLASS only (#7145)
JIT/AOT	Compile-time only — invalid targets must fail before codegen (no runtime fallback)
Tests	test/compliance/cases/language/allow_dynamic_properties_param_target.phpt

Do not add C runtime checks — reject in PHP compile path.

Done when

• VM compile of parameter repro fails before runtime with message equivalent to Zend (cannot target parameter, allowed targets: class)
• No successful echo "compiled" on VM for parameter repro
• Function-target repro also fails at compile time
• ./script/ci-fast.sh --filter allow_dynamic_properties_param green
• No unrelated deprecation noise on the repro file when compile fails

Verification

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && vendor/bin/phpunit --filter allow_dynamic_properties_param'

Links

• North star: Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492
• Delayed validation (promoted param → property is valid in 8.4): Language: #[\DelayedTargetValidation] attribute — validate attribute targets at compile time (PHP 8.4, zend_attributes.c) #5124
• Builtin attribute registration: php-in-php: #[\Deprecated] builtin attribute — register in ext/standard not lib/VM/AttributeSupport (zend_attributes.stub.php) #7145

[PurHur]

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

[PurHur]

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

[PurHur]

Merged via #5808

Verification: VM compile of function f(#[\AllowDynamicProperties] int $x) {} now fails with Attribute "AllowDynamicProperties" cannot target parameter (allowed targets: class) and exit 255 (no compiled output). PHPUnit: allow_dynamic_properties_param_target + AttributeNamesDuplicateTest::testRejectsAllowDynamicPropertiesOnParameter green in Docker.