docs(prop): document the Exception::getMessage refcount leak#737
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ptondereau wants to merge 1 commit into
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docs(prop): document the Exception::getMessage refcount leak#737ptondereau wants to merge 1 commit into
ptondereau wants to merge 1 commit into
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Hit this while building a PHPStan rule on top of biscuit-php and noticing memory growing on every datalog parse error. Tracking it down: any `#[php(prop)]` field holding an owned refcounted type (String, Vec, etc.) leaks one zend_string per call when PHP's Exception::getMessage reads it. Direct property access (`$obj->prop`) is unaffected — only the `zval_get_string + RETURN_STR` pattern used by Exception's final C methods triggers the orphaned refcount. Adds a regression test (marked `#[ignore]` so CI stays green) and documentation on the `#[php(prop)]` attribute with two workarounds: either rename the shadow field, or mirror to the parent's real slot via `zend_update_property_stringl`. Proper fix needs either an upstream PHP patch or a deeper change to how field props store their value.
Coverage Report for CI Build 25812964747Coverage remained the same at 66.23%Details
Uncovered ChangesNo uncovered changes found. Coverage RegressionsNo coverage regressions found. Coverage Stats
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Bencher Report| Branch | fix/string-prop-getter-zend-string-leak |
| Testbed | PHP 8.4.21 (cli) (built: May 8 2026 04:58:07) (NTS) |
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Description
Spotted this while building a PHPStan rule on top of biscuit-php and watching memory grow on every datalog parse error. Drilling in: any
#[php(prop)]field holding an owned refcounted type leaks onezend_stringeach time PHP'sException::getMessagereads it. Direct property access from PHP code is unaffected; the leak only fires through Exception's final C methods, which assume real property storage and orphan the refcount we put in thervslot.This PR ships the regression test (marked
#[ignore]so CI stays green) and adds docs on the#[php(prop)]attribute with two workarounds: rename the shadow field or mirror the value into the parent's real slot viazend_update_property_stringl. The proper fix is bigger and out of scope here, either an upstream PHP patch to dtor thervslot or a deeper change to how field props store their value.Opening as a draft for visibility while we settle the long-term direction.
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