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Language: read property on null must throw Error not E_WARNING (PHP 8.0+, zend_execute.c) #7431
Description
Category
language · runtime
Problem
Since PHP 8.0, reading an instance property on null ($null->prop) throws a catchable Error, not E_WARNING with execution continuing. This compiler emits a warning and returns an empty value, so catch (Error $e) never runs.
Verified on master (2026-06-07):
./script/docker-exec.sh -- bash -lc 'php bin/vm.php test/repro-maintainer/parity_null_property_read_error.php'VM today: PHP Warning: Attempt to read property "prop" on null then prints no throw.
Zend/php-src: Error: Attempt to read property "prop" on null — catchable, no continuation.
Distinct from #4851 (undefined method dispatch fatals) and #4980 (nullsafe ?-> short-circuit).
php-src reference
- php/php-src
Zend/zend_execute.c—ZEND_FETCH_OBJ_Ron null base - php/php-src
Zend/zend_types.h—IS_NULLbase handling (PHP 8.0 behavior change)
Repro
test/repro-maintainer/parity_null_property_read_error.php:
<?php
try {
$x = null;
$y = $x->prop;
echo "no throw\n";
} catch (Error $e) {
echo $e::class, ': ', $e->getMessage(), "\n";
}| Engine | Output |
|---|---|
| Zend | Error: Attempt to read property "prop" on null |
| VM | Warning + no throw |
Also verify echo $null->prop and $null->prop++ throw (not warn).
Scope (this repo)
| Layer | Path |
|---|---|
| VM | property fetch on null base in lib/VM.php / lib/VM/PropertyAccess.php — throw Error via VM exception path |
| JIT/AOT | mirror in property fetch lowering |
| Tests | test/compliance/cases/language/null_property_read_error.phpt |
PHP-in-PHP — shrink warning-only C paths if any.
Done when
- Repro prints catchable
Erroron VM - No
E_WARNINGfor this path under default error reporting - JIT/AOT
.phptgreen -
./script/ci-fast.sh --filter null_property_readgreen
Related
- Language: catchable Error for undefined method on objects — VM dispatch (zend_execute.c) #4851 · Language: isset()/empty() on nullsafe ?-> chain — short-circuit like Zend (zend_compile.c) #4980 · Language: unset() on nullsafe ?-> chain — no-op when receiver is null (zend_compile.c) #4983 · Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492
Activity
PurHur commentedon Jun 7, 2026
Maintainer repro script:
test/repro-maintainer/— see issue body; VM-verified 2026-06-07 onmaster.PurHur commentedon Jun 7, 2026
claim: worker-lane-a — starting this run
Fix null property read to throw catchable Error (#7431) (#7445)
PurHur commentedon Jun 7, 2026
Merged via #7445.
Verification
```bash
./script/docker-exec.sh -- bash -lc 'php bin/vm.php test/repro-maintainer/parity_null_property_read_error.php'
Error: Attempt to read property "prop" on null
./script/docker-exec.sh -- bash -lc 'vendor/bin/phpunit --filter null_property_read'
OK (3 tests, 3 assertions)
```
VM:
$null->prop/echo $null->prop/$null->prop++throw catchableError(inc/dec uses Zend increment/decrement message). JIT: uncaught path fatal viaErrorRaise; try/catch catchable path usesTryCatchHelper(VM phpt skipped in umbrella JITTest until MCJIT dispatch stable #98).