|  support |  documentation |  report a bug |  advanced search |  search howto |  statistics |  random bug |  login
Bug #79827 debug_backtrace() does not return passed args
Submitted: 2020-07-10 14:08 UTC Modified: 2020-07-10 19:09 UTC
From: michael dot vorisek at email dot cz Assigned:
Status: Duplicate Package: Scripting Engine problem
PHP Version: 7.4.8 OS: any
Private report: No CVE-ID: None
View Add Comment Developer Edit
Welcome! If you don't have a Git account, you can't do anything here.
You can add a comment by following this link or if you reported this bug, you can edit this bug over here.
Block user comment
Status: Assign to:
Bug Type:
From: michael dot vorisek at email dot cz
New email:
PHP Version: OS:


 [2020-07-10 14:08 UTC] michael dot vorisek at email dot cz
debug_backtrace() currently returns args by reference, ie. the returned args variables, not the passed values.

Very hard to debug, backtrace should always return the passed data.

Test script:
function x(string $filename) {
    $filename = realpath($filename);
    $trace = debug_backtrace();


Expected result:
array(1) {

Actual result:
array(1) {
  string(21) "non_existing_file.txt"


Add a Patch

Pull Requests

Add a Pull Request


AllCommentsChangesGit/SVN commitsRelated reports
 [2020-07-10 14:10 UTC]
-Status: Open +Status: Duplicate
 [2020-07-10 14:10 UTC]
Duplicate of bug #71547.
 [2020-07-10 16:09 UTC] michael dot vorisek at email dot cz
Any functions that rely on backtrace are currently affected.

Is the penalty of copy on write really that high and is there a will to fix this issue?
 [2020-07-10 19:00 UTC] michael dot vorisek at email dot cz
This actually violates the language definition, as

$filename = realpath($filename);

is not an assigment by reference!
 [2020-07-10 19:09 UTC]
As I have already indicated with the link above, this is an intentional behavior change in PHP 7.0, which is mentioned in

It has nothing to do with by-value / by-reference passing, it is just a question of whether the original or current values of parameter variables are provided. Not providing the original values removes the need to copy the original values for every call. Extensions like xdebug remember original values, with the associated performance cost.
PHP Copyright © 2001-2023 The PHP Group
All rights reserved.
Last updated: Mon Dec 04 22:01:28 2023 UTC