Regression: XMLWriter string args (null) skip soft-null DEP + ValueError arg shape — Zend php_xmlwriter.c

[PurHur]

Category

Regression: · php-src-strict · XMLWriter null→string soft-deprecate + empty-name ValueError

Problem

XMLWriter::{startElement,writeElement,startAttribute,writeAttribute,text,writeComment,writeCdata,writeRaw,setIndentString}(null) on Zend soft-deprecates null-to-string for the string parameter, then either throws empty-name ValueError (name APIs) or succeeds (content APIs). VM coerces silently (no DEP) and name APIs throw a different ValueError shape (Argument #1 ($name) / '' / writeElement reports startElement).

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

Repro	Zend 8.2+	VM (2026-08-16)
startElement(null)	DEP $name + ValueError: … Argument #2 must be a valid element name, "" given	no DEP + Argument #1 ($name) … '' given
writeElement(null)	DEP + Argument #2 ($content) must be a valid element name, "" given	no DEP + startElement(): Argument #1 ($name) …
text(null) / writeComment(null) / writeCdata(null) / writeRaw(null) / setIndentString(null)	DEP then ok	ok, no DEP

php-src reference

• php/php-src ext/xmlwriter/php_xmlwriter.c — Z_PARAM_STR soft-null + name validation ValueError
• php/php-src ext/xmlwriter/xmlwriter.stub.php — string params

PHP implementation target

• ext/xmlwriter/XmlWriterClassMethod.php — soft-null via VmString::stringBuiltinArgForFrame(..., false) (same shape as Regression: SimpleXMLElement::addChild/addAttribute(null) TypeError — Zend Deprecated + ValueError empty (ext/simplexml/sxe.c) #31554)
• ext/xmlwriter/VmXmlWriter.php — Zend ValueError arg ordinal/message for empty names; writeElement must not surface startElement
• JIT/AOT: emit soft-null DEP for compile-time null literals where lowered
• No new runtime/*.c

Repro

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

Done when

• Repro matches Zend DEP + ValueError / ok paths on VM (and JIT where lowered)
• 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 #31613.

Fix: Soft-null Z_PARAM_STR for XMLWriter / xmlwriter_* string args via VmNullStringParamDeprecation (php-src php_xmlwriter.c); empty-name ValueError matches Zend Argument #2 quirks (startElement / writeElement / startAttribute / writeAttribute).

Verification:

./script/docker-exec.sh -- bash -lc 'php bin/vm.php test/repro/maintainer_gap_xmlwriter_null_soft.php'
# DEP + ValueError / ok — matches Zend

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

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && vendor/bin/phpunit test/compliance/XmlwriterNullStringArgsSoft31610VMTest.php'
# OK (1 test)
./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && vendor/bin/phpunit test/compliance/XmlwriterNullStringArgsSoft31610JITTest.php'
# OK (1 test)