Enhancements

[ExUnit] Add on_exit/1 callbacks that are guaranteed to run once the test process exits and always in another process

[Kernel] Store documentation in the abstract code to avoid loading them when the module is loaded

[Kernel] Add get_in/2, put_in/3, update_in/3 and get_and_update_in/3 to handle nested data structure operations

[Kernel] Add get_in/1, put_in/2, update_in/2 and get_and_update_in/2 to handle nested data structure operations via paths

[Mix] Add Mix.Config to ease definition of configuration files

[Mix] Add mix loadconfig task that can be called multiple times to load external configs

[Mix] Support --config option on mix run

[Mix] Support HTTP_PROXY and HTTPS_PROXY on Mix url commands

[Mix] Support --names options in mix help which emit only names (useful for autocompletion)

[Protocol] Add Protocol.consolidate/2, Protocol.consolidated?/1 and a mix compile.protocols task for protocol consolidation

[Protocol] Add Protocol.derive/3 for runtime deriving of a struct

[String] Add String.chunk/2

[Struct] Add support for @derive before defstruct/2 definitions

Bug fixes

[File] File.rm now consistently deletes read-only across operating systems

[Kernel] Ensure Mix _build structure works on Windows when copying projects

[Kernel] Ensure 1.0E10 (with uppercase E) is also valid syntax

[Mix] Fix mix do task for Windows' powershell users

[Path] Fix Path.absname("/") and Path.expand("/") to return the absolute path "/".

Soft deprecations (no warnings emitted)

[Kernel] size/1 is deprecated, please use byte_size/1 or tuple_size/1 instead

[ExUnit] teardown/2 and teardown_all/2 are deprecated in favor of on_exit/1 callbacks

Deprecations

[Access] Access.access/2 is deprecated in favor of Access.get/2

[Dict] Dict.Behaviour is deprecated in favor of Dict

[Kernel] Application.Behaviour, GenEvent.Behaviour, GenServer.Behaviour and Supervisor.Behaviour are deprecated in favor of Application, GenEvent, GenServer and Supervisor

[Kernel] defexception/3 is deprecated in favor of defexception/1

[Kernel] raise/3 is deprecated in favor of reraise/2

[Kernel] set_elem/3 is deprecated in favor of put_elem/3

[Kernel] Passing an atom var!/1 is deprecated, variables can be built dynamically with Macro.var/2

[Mix] Exceptions that define a :mix_error field to be compatible with Mix are no longer supported. Instead please provide a :mix field and use Mix.raise/1 and Mix.raise/2

Backwards incompatible changes

[Access] Kernel.access/2 no longer exists and the Access protocol now requires get/2 (instead of access/2) and get_and_update/3 to be implemented

[Kernel] Retrieving docs as module.__info__(:docs) is no longer supported, please use Code.get_docs/2 instead

[Kernel] Code.compiler_options/1 no longer accepts custom options, only the ones specified by Elixir (use mix config instead)

[Mix] mix new no longer generates a supevision tree by default, please pass --sup instead

[Task] Tasks are automatically linked to callers and a failure in the task will crash the caller directly