SimpleXML: soft-null xpath($expression) DEP + Invalid expression + false (#31530)

[PurHur]

Summary

• Soft-null $expression on SimpleXMLElement::xpath via VmString::stringBuiltinArgForFrame(..., false) (php-src ext/simplexml/sxe.c / Regression: SimpleXMLElement::xpath(null) TypeError — Zend Deprecated + Warning + false (ext/simplexml/sxe.c) #31530) — deprecate then evaluate; empty/invalid → E_WARNING + false (not TypeError).
• JIT user-script path: null literal routes through JitStringBuiltinArg::lowerTrimFamilyString then empty-path invalid-expression fold.
• Compliance VM + JIT guards (xpath_null_soft.phpt).

Closes #31530

Test plan

• ./script/docker-exec.sh -- bash -lc 'php bin/vm.php test/repro/maintainer_gap_simplexml_xpath_null.php'
• ./script/docker-exec.sh -- bash -lc 'php bin/jit.php test/repro/maintainer_gap_simplexml_xpath_null.php'
• ./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php vendor/bin/phpunit test/compliance/SimplexmlXpathNullSoft31530VMTest.php test/compliance/SimplexmlXpathNullSoft31530JITTest.php'

Verification output

# VM
DEP:SimpleXMLElement::xpath(): Passing null to parameter #1 ($expression) of type string is deprecated
E2:SimpleXMLElement::xpath(): Invalid expression
false

# JIT
DEP:… / E2:… Invalid expression / false

# PHPUnit
OK (1 test) ×2 (VM + JIT)

php-src-strict; no new runtime/*.c.

Made with Cursor