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.

Tue, Mar 22, 2011 - xdebug 2.1.1rc1

= Fixed bugs:

= Debugger
- Fixed bug #518: Removed CLASSNAME pseudo-property optional.
- Fixed bug #592: Xdebug crashes with run after detach.
- Fixed bug #596: Call breakpoint never works with instance methods, only
static methods.
- Fixed JIT mode in the debugger so that it works for xdebug_break() too.

= Profiler
- Fixed bug #631: Summary not written when script ended with "exit()".
- Fixed bug #639: Xdebug profiling: output not correct - missing 'cfl='.
- Fixed bug #642: Fixed line numbers for offsetGet, offsetSet,
__get/__set/__isset/__unset and __call in profile files and stack
traces/function traces.
- Fixed bug #643: Profiler gets line numbers wrong.
- Fixed bug #653: XDebug profiler crashes with %H in file name and non
standard port.

= Others
- Fixed bug #651: Incorrect code coverage after empty() in conditional.
- Fixed bug #654: Xdebug hides error message in CLI.
- Fixed bug #665: Xdebug does not respect display_errors=stderr.
Patch by Ben Spencer <dangerous.ben@gmail.com>
- Fixed bug #670: Xdebug crashes with broken "break x" code.