Make finfo_open() $magic_database nullable

Empty string was interpreted as a special value here, which indicates
that the default magic database should be used. It makes more sense
to use null for this purpose.

The documentation also explicitly mentions that null can be used.

Author: nikic

ext/fileinfo/fileinfo.c

@@ -215,7 +215,7 @@ PHP_FUNCTION(finfo_open)
 	char resolved_path[MAXPATHLEN];
 	zend_error_handling zeh;
 
-	if (zend_parse_parameters(ZEND_NUM_ARGS(), "|lp", &options, &file, &file_len) == FAILURE) {
+	if (zend_parse_parameters(ZEND_NUM_ARGS(), "|lp!", &options, &file, &file_len) == FAILURE) {
 		RETURN_THROWS();
 	}
 

ext/fileinfo/fileinfo.stub.php

@@ -5,7 +5,7 @@
 class finfo
 {
     /** @alias finfo_open */
-    public function __construct(int $flags = FILEINFO_NONE, string $magic_database = "") {}
+    public function __construct(int $flags = FILEINFO_NONE, ?string $magic_database = null) {}
 
     /**
      * @param resource|null $context
@@ -29,7 +29,7 @@ public function set_flags(int $flags) {}
 }
 
 /** @return resource|false */
-function finfo_open(int $flags = FILEINFO_NONE, string $magic_database = "") {}
+function finfo_open(int $flags = FILEINFO_NONE, ?string $magic_database = null) {}
 
 /**
  * @param resource $finfo

ext/fileinfo/fileinfo_arginfo.h

@@ -1,9 +1,9 @@
 /* This is a generated file, edit the .stub.php file instead.
- * Stub hash: be858509df27550b51d8a7a51a3629eceb6d0aa6 */
+ * Stub hash: 648085986695281bd5a8fb536d5ec6c2a9f8c6e8 */
 
 ZEND_BEGIN_ARG_INFO_EX(arginfo_finfo_open, 0, 0, 0)
 	ZEND_ARG_TYPE_INFO_WITH_DEFAULT_VALUE(0, flags, IS_LONG, 0, "FILEINFO_NONE")
-	ZEND_ARG_TYPE_INFO_WITH_DEFAULT_VALUE(0, magic_database, IS_STRING, 0, "\"\"")
+	ZEND_ARG_TYPE_INFO_WITH_DEFAULT_VALUE(0, magic_database, IS_STRING, 1, "null")
 ZEND_END_ARG_INFO()
 
 ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO_EX(arginfo_finfo_close, 0, 1, _IS_BOOL, 0)