Maintenance

During the lifetime of a minor version, new releases (patch versions) are

published on a monthly basis. This document describes the boundaries of

acceptable changes.

**Bug fixes** are accepted under the following conditions:

* The change does not break valid unit tests;

* New unit tests cover the bug fix;

* The current buggy behavior is not widely used as a "feature".

..note::

When documentation (or phpdoc) is not in sync with the code, code behavior

should always be considered as being the correct one.

Besides bug fixes, other minor changes can be accepted in a patch version:

* **Performance improvement**: Performance improvement should only be accepted

if the changes are local (located in one class) and only for algorithmic

issues (any such patches must come with numbers that show a significant

improvement on real-world code);

* **Newer versions of PHP/HHVM**: Fixes that add support for newer versions of

PHP or HHVM are acceptable if they don't break the unit test suite;

* **Newer versions of popular OSes**: Fixes that add support for newer versions

of popular OSes (Linux, MacOS and Windows) are acceptable if they don't break

the unit test suite;

* **Translations**: Translation updates and additions are accepted;

* **External data**: Updates for external data included in Symfony can be

updated (like ICU for instance);

* **Version updates for Composer dependencies**: Changing the minimal version

of a dependency is possible, bumping to a major one or increasing PHP

minimal version is not;

* **Coding standard and refactoring**: Coding standard fixes or code

refactoring are not recommended but can be accepted for consistency with the

existing code base, if they are not too invasive, and if merging them on

master would not lead to complex branch merging;

* **Tests**: Tests that increase the code coverage can be added.

Anything not explicitly listed above should be done on the next minor or major

version instead (aka the *master* branch). For instance, the following changes

are never accepted in a patch version:

* **New features**;

* **Backward compatibility breaks**: Note that backward compatibility breaks

can be done when fixing a security issue if it would not be possible to fix

it otherwise;

* **Support for external platforms**: Adding support for new platforms (like

Google App Engine) cannot be done in patch versions;

* **Exception messages**: Exception messages must not be changed as some

automated systems might rely on them (even if this is not recommended);

* **Adding new Composer dependencies**;

* **Support for newer major versions of Composer dependencies**: Taking into

account support for newer versions of an existing dependency is not

acceptable.

* **Web design**: Changing the web design of built-in pages like exceptions,

the toolbar or the profiler is not allowed.

..note::

This policy is designed to enable a continuous upgrade path that allows one

to move forward with newest Symfony versions in the safest way. One should

be able to move PHP versions, OS or Symfony versions almost independently.

That's the reason why supporting the latest PHP versions or OS features is

considered as bug fixes.

Before working on a patch, you must determine on which branch you need to

work:

* ``2.3``, if you are fixing a bug for an existing feature (you may have

to choose a higher branch if the feature you are fixing was introduced

in a later version);

* ``master``, if you are adding a new feature.

* ``2.3``, if you are fixing a bug for an existing feature or want to make a

change that falls into the:doc:`list of acceptable changes in patch versions

</contributing/code/maintenance>` (you may have to choose a higher branch if

the feature you are fixing was introduced in a later version);

* ``master``, if you are adding a new feature.

..note::

be fixed. The end of this period is referenced as being the *end of life* of

a release.

..note::

The:doc:`maintenance document</contributing/code/maintenance>` describes

the boundaries of acceptable changes during maintenance.

Symfony Versions

* :doc:`Bugs</contributing/code/bugs>`

* :doc:`Patches</contributing/code/patches>`

* :doc:`Reviewing Issues and Patches</contributing/community/reviews>`

* :doc:`Maintenance</contributing/code/maintenance>`

* :doc:`The Core Team</contributing/code/core_team>`

* :doc:`Security</contributing/code/security>`

* :doc:`Tests</contributing/code/tests>`