Regression: file/path builtins null filename — TypeError not empty-string coerce (re-#13354, ext/standard/filestat.c) #15067

Category

stdlib · php-src-strict · regression (closed #13354, repro red again)

Problem

Without declare(strict_types=1), Zend coerces null path/filename operands to "" and continues. VM rejects with TypeError on the first call.

Use shared internal-arg coercion (VmString::coerceStringBuiltinArg / JitStringBuiltinArg) — same family as touch(null) regressions (#13343).

php-src reference

• php/php-src ext/standard/filestat.c — php_stat, file_exists
• php/php-src ext/standard/basic_functions.c — pathinfo, basename, dirname

PHP implementation target

• ext/standard/file_exists.php, is_file.php, is_dir.php, filesize.php, rename.php, pathinfo.php, basename.php, dirname.php
• Reuse existing null→"" guards used by other file builtins

Repro (verified 2026-07-02)

./script/docker-exec.sh -- php bin/vm.php test/repro/maintainer_gap_file_stat_null_coerce.php
# TypeError: file_exists(): Argument #1 ($filename) must be of type string, null given

./script/docker-exec.sh -- php test/repro/maintainer_gap_file_stat_null_coerce.php
# ok

Compliance guard: test/compliance/cases/stdlib/file_stat_null_coerce.phpt

Done when

• All builtins in repro coerce null → "" and match Zend warnings/output
• file_stat_null_coerce.phpt green on VM (+ JIT guard if applicable)
• No new C in runtime/ — PHP builtins + shared coercion helpers only