Repository navigation
Regression: preg_match()/preg_match_all() empty pattern — $matches array not NULL (re-#12688, ext/pcre/php_pcre.c) #17597
Description
Category
Regression · php-src-strict · stdlib
Problem
Closed in #12688 (2026-06-27) but master regressed: on empty-pattern compile failure Zend leaves by-ref $matches NULL; VM/JIT initialize it to an empty array.
| Repro | Zend 8.2 | VM (2026-07-10) | JIT (2026-07-10) |
|---|---|---|---|
preg_match('', 'x', $m) after warning |
NULL |
array() |
array() |
preg_match_all('', 'x', $m) after warning |
NULL |
array() |
array() |
php-src reference
- php/php-src
ext/pcre/php_pcre.c—php_pcre_match_impl()leaves$matchesunset/NULL when compile fails - Pure-PHP path:
ext/standard/VmPregPure.php(pregMatch/pregMatchAllnull-ovector branch sets$matches = [])
PHP implementation target
ext/standard/VmPregPure.php— do not assign$matcheson empty/invalid pattern (match Zend unset semantics)ext/standard/VmPreg.php/ JIT preg lowering — same guard; share helper with duplicate-named compile-failure path (Regression: preg_match()/preg_replace() duplicate named subpatterns match — compile must fail (re-#14880, ext/pcre/php_pcre.c) #17584)
Repro
./script/docker-exec.sh -- bash -lc 'php bin/vm.php test/repro/maintainer_gap_preg_match_empty_pattern_matches_null.php'
./script/docker-exec.sh -- bash -lc 'php bin/jit.php test/repro/maintainer_gap_preg_match_empty_pattern_matches_null.php'Done when
-
maintainer_gap_preg_match_empty_pattern_matches_null.phpgreen on VM + JIT (+ AOT if wired) - Compliance guard under
test/compliance/cases/stdlib/for empty-pattern$matchesNULL - php-src-strict; no php-compiler-strict shortcut
Activity
PurHur commentedon Jul 10, 2026
claim: PHP Compiler STD Lib — starting this run
Stdlib: preg_match() empty pattern leaves $matches NULL (#17597) (#17603
PurHur commentedon Jul 10, 2026
Merged in #17603.
Root cause: VM
preg_match()execute path wrotearray()to by-ref$matchesonfalse(compile failure). Zend leaves it unset/NULL;preg_match_all()already called$target->null().Fix:
ext/standard/preg_match.php— use$target->null()on failure. JIT/AOT__compiler_preg_match_exbridge was already correct.Verification:
php bin/vm.php test/repro/maintainer_gap_preg_match_empty_pattern_matches_null.php→ okphp bin/jit.phpsame repro → okvendor/bin/phpunit --filter preg_match_empty_pattern_matches_null→ OK (VM + JIT compliance)PurHur commentedon Jul 10, 2026
claim: PHP Compiler STD Lib Advanced — batch (ext/pcre #17597 regression from #17623)
PurHur commentedon Jul 10, 2026
Merged in #17673.
Root cause: #17623 (
ed0e44cb4) regressed #17603 by writingarray()to by-ref$matcheson all compile failures; Zend leaves the out-parameter unset.Fix: skip writing
$matcheswhenpregMatch*returnsfalse(VM + JIT/AOT bridge).Verification:
maintainer_gap_preg_match_empty_pattern_matches_null.phpgreen on VM + JIT; duplicate-named repro still green.Stdlib: preg_match() compile failure leaves $matches unset (#17597) (#…