ext/ftp: declare the false returned by ftp_nb_fget() and ftp_nb_fput()

Both answer an already busy connection with a warning and RETURN_FALSE,
the same guard ftp_nb_get() and ftp_nb_put() have, and those two already
declare int|false.

Author: lacatoire

UPGRADING

@@ -645,6 +645,11 @@ PHP 8.6 UPGRADE NOTES
     null was never returned. filter_input_array() is unaffected: it still
     returns null when the requested superglobal does not exist.
 
+- FTP:
+  . ftp_nb_fget() and ftp_nb_fput() return type has been widened from int to
+    int|false, matching ftp_nb_get() and ftp_nb_put(). All four return false
+    when the connection is already in use.
+
 - GMP:
   . gmp_fact() now throws a ValueError if $num does not fit into an unsigned
     long.

ext/ftp/ftp.stub.php

@@ -107,7 +107,7 @@ function ftp_systype(FTP\Connection $ftp): string|false {}
     function ftp_fget(FTP\Connection $ftp, $stream, string $remote_filename, int $mode = FTP_BINARY, int $offset = 0): bool {}
 
     /** @param resource $stream */
-    function ftp_nb_fget(FTP\Connection $ftp, $stream, string $remote_filename, int $mode = FTP_BINARY, int $offset = 0): int {}
+    function ftp_nb_fget(FTP\Connection $ftp, $stream, string $remote_filename, int $mode = FTP_BINARY, int $offset = 0): int|false {}
     function ftp_pasv(FTP\Connection $ftp, bool $enable): bool {}
     function ftp_get(FTP\Connection $ftp, string $local_filename, string $remote_filename, int $mode = FTP_BINARY, int $offset = 0): bool {}
     function ftp_nb_get(FTP\Connection $ftp, string $local_filename, string $remote_filename, int $mode = FTP_BINARY, int $offset = 0): int|false {}
@@ -117,7 +117,7 @@ function ftp_nb_continue(FTP\Connection $ftp): int {}
     function ftp_fput(FTP\Connection $ftp, string $remote_filename, $stream, int $mode = FTP_BINARY, int $offset = 0): bool {}
 
     /** @param resource $stream */
-    function ftp_nb_fput(FTP\Connection $ftp, string $remote_filename, $stream, int $mode = FTP_BINARY, int $offset = 0): int {}
+    function ftp_nb_fput(FTP\Connection $ftp, string $remote_filename, $stream, int $mode = FTP_BINARY, int $offset = 0): int|false {}
     function ftp_put(FTP\Connection $ftp, string $remote_filename, string $local_filename, int $mode = FTP_BINARY, int $offset = 0): bool {}
     function ftp_append(FTP\Connection $ftp, string $remote_filename, string $local_filename, int $mode = FTP_BINARY): bool {}
     function ftp_nb_put(FTP\Connection $ftp, string $remote_filename, string $local_filename, int $mode = FTP_BINARY, int $offset = 0): int|false {}

ext/ftp/ftp_arginfo.h

@@ -0,0 +1,20 @@
+--TEST--
+The non-blocking transfer functions declare the false their in_use guard returns
+--EXTENSIONS--
+ftp
+--FILE--
+<?php
+
+/* ftp_nb_fget(), ftp_nb_get(), ftp_nb_fput() and ftp_nb_put() all answer an
+ * already busy connection with false; ftp_nb_continue() has no such guard. */
+foreach (['ftp_nb_fget', 'ftp_nb_get', 'ftp_nb_fput', 'ftp_nb_put', 'ftp_nb_continue'] as $function) {
+    printf("%-17s %s\n", $function, (new ReflectionFunction($function))->getReturnType());
+}
+
+?>
+--EXPECT--
+ftp_nb_fget       int|false
+ftp_nb_get        int|false
+ftp_nb_fput       int|false
+ftp_nb_put        int|false
+ftp_nb_continue   int