Xdebug is a debugging and productivity extension for PHP

Xdebug and provides a range of features to improve the PHP development
experience.

Step Debugging
A way to step through your code in your IDE or editor while the script is
executing.

Improvements to PHP's error reporting
An improved var_dump() function, stack traces for Notices, Warnings, Errors
and Exceptions to highlight the code path to the error

Tracing
Writes every function call, with arguments and invocation location to disk.
Optionally also includes every variable assignment and return value for
each function.

Profiling
Allows you, with the help of visualisation tools, to analyse the
performance of your PHP application and find bottlenecks.

Code Coverage Analysis
To show which parts of your code base are executed when running unit tests
with PHP Unit.

Wed, Dec 02, 2015 - xdebug 2.4.0RC2

= Fixed bugs:

- Fixed issue #1181: Remote debugging does not handle exceptions after using
zend_read_property
- Fixed issue #1189: Remove address attribute from remote debugging responses
- Fixed issue #1194: The error message is doubly HTML-encoded with assert()
- Fixed issue #1210: Segfault with code coverage dead code analysis and
foreach on PHP 7
- Fixed issue #1215: SIGSEGV if xdebug.trace_output_dir directory does not
exist
- Fixed issue #1217: xdebug.show_error_trace should not be enabled by default
- Fixed issue #1218: Xdebug messes with the exception code, by casting it to
int
- Fixed issue #1219: Set default value for xdebug.overload_var_dump to 2 to
include file / line numbers by default
- Use long for PHP 5, and zend_long for PHP 7 for ini settings in the globals