Regression: SimpleXMLElement::xpath(null) TypeError — Zend Deprecated + Warning + false (ext/simplexml/sxe.c)

[PurHur]

Category

Regression: · php-src-strict · SimpleXMLElement::xpath null expression coerce

Problem

SimpleXMLElement::xpath(null) on Zend soft-deprecates null-to-string for $expression, emits Warning: … Invalid expression, and returns false. VM hard-TypeErrors: Argument #1 ($expression) must be of type string (no deprecation, no warning path). Distinct from ctor null gap #31514 and from invalid-expression [] vs false history (#22720).

Probed 2026-08-16 — host Zend PHP 8.2.32 vs php bin/vm.php.

Repro	Zend 8.2+	VM (2026-08-16)
$x = new SimpleXMLElement('<a><b/></a>'); $x->xpath(null)	Deprecated $expression + Warning Invalid expression + false	TypeError: … Argument #1 ($expression) must be of type string

php-src reference

• php/php-src ext/simplexml/sxe.c — xpath string coerce + libxml evaluate → false + warning on invalid
• php/php-src ext/simplexml/simplexml.stub.php — xpath(string $expression): array|false

PHP implementation target

• ext/simplexml/ SimpleXMLElement::xpath — soft-deprecate null→string under php-src-strict, then invalid-expression warning + false
• Reuse shared string-arg soft-null guards where possible; no new runtime/*.c

Repro

./script/docker-exec.sh -- bash -lc 'php test/repro/maintainer_gap_simplexml_xpath_null.php'
./script/docker-exec.sh -- bash -lc 'php bin/vm.php test/repro/maintainer_gap_simplexml_xpath_null.php'

Done when

• xpath(null) emits Zend deprecation + Invalid expression warning and returns false
• Targeted compliance/PHPUnit guard
• php-src-strict; no php-compiler-strict shortcut

[PurHur]

claim: PHP Compiler Ext — DOM & XML — starting this run

[PurHur]

Merged via PR #31541.

Fix: Soft-null $expression on SimpleXMLElement::xpath via VmString::stringBuiltinArgForFrame(..., false) (php-src sxe.c); empty/invalid still warns + returns false. JIT null literal routes through soft-null lower then Invalid expression fold.

Verification:

./script/docker-exec.sh -- bash -lc 'php bin/vm.php test/repro/maintainer_gap_simplexml_xpath_null.php'
# DEP:…Passing null… deprecated
# E2:…Invalid expression
# false

./script/docker-exec.sh -- bash -lc 'php bin/jit.php test/repro/maintainer_gap_simplexml_xpath_null.php'
# same

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php vendor/bin/phpunit test/compliance/SimplexmlXpathNullSoft31530VMTest.php test/compliance/SimplexmlXpathNullSoft31530JITTest.php'
# OK (1 test) ×2