Add `\f` as a whitespace character in `trim`

[LamentXU123]

Description

Hi.
The trim function will remove whitespaces in the parameters. The default characters are \n\r\t\v\0, source.
I think maybe \f is missing here? In most of the cases in php (such as is_numeric, source) we recognized \f as a whitespace. Also in libc isspace.c we too include \f as whitespaces:

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 2005,2007 Oracle.  All rights reserved.
 *
 * $Id: myisspace.c,v 1.4 2007/05/17 15:14:54 bostic Exp $
 */

 /*
  * myisspace --
  *
  * PUBLIC: #ifndef HAVE_ISSPACE
  * PUBLIC: int myisspace __P((int));
  * PUBLIC: #endif
  */
int
myisspace(c)
int c;
{
	return (c == '\t' || c == '\n' ||
		c == '\v' || c == '\f' || c == '\r' || c == ' ' ? 1 : 0);
}

Since the document indicate that trim would "Strip whitespace (or other characters) from the beginning and end of a string", I think \f may be an unexpected case here as it is usually treated as whitespaces. Thanks.

PHP Version

all version

Operating System

No response

[devnexen]

python, rust ... to mention a handful, trim whitspaces, form feed included. it sounds legit to expect the same here.

[devnexen]

btw since you understood well the problem, feel free to open a PR ;)

[Girgias]

While I agree this makes sense, you may still want to send a quick email to the Internals mailing list to make sure nobody complains, as it is technically a BC break.