finfo::file(): empty $filename ValueError reports argument #2 ($flags) #24289

finfo::file() reports the wrong argument when $filename is empty.

<?php
$finfo = new finfo();
try { finfo_file($finfo, ''); } catch (Throwable $e) { echo "procedural: ", $e::class, ': ', $e->getMessage(), "\n"; }
try { $finfo->file(''); } catch (Throwable $e) { echo "method: ", $e::class, ': ', $e->getMessage(), "\n"; }

Output on PHP 8.4.x and 8.5.x:

procedural: ValueError: finfo_file(): Argument #2 ($filename) must not be empty
method: ValueError: finfo::file(): Argument #2 ($flags) must not be empty

(8.3 prints the same with "cannot be empty".)

Expected for the method: finfo::file(): Argument #1 ($filename) must not be empty.

The same C function serves both finfo_file($finfo, $filename, ...) and finfo::file($filename, $flags, ...), and the argument number is hardcoded:

• master and PHP-8.5, ext/fileinfo/fileinfo.c, PHP_FUNCTION(finfo_file): zend_argument_must_not_be_empty_error(2);
• PHP-8.4, php_finfo_get_type(): buffer_param_num = (mimetype_emu ? 1 : 2) is used for both the empty check and the null byte check, so on 8.4 the null byte TypeError of the method names $flags too.

A possible fix is to pass getThis() ? 1 : 2 (the null byte check on master and 8.5 is already correct, as it goes through zend_parse_method_parameters()). finfo_file_001.phpt only covers the procedural form.