Changes

2.4

Breaking changes

use-package no longer requires diminish as a dependency, allowing people to decide whether they want to use diminish or delight. This means that if you do use diminish, you'll now need to pull it into your configuration before any use of the :diminish kewyord. For example:
```
    (use-package diminish :ensure t)
```
Emacs 24.3 or higher is now a requirement.
The :defer-install keyword has been removed. It may reappear as an add-on module for use-package in a future release. See issue #442 for more details.
There is no longer a use-package-debug option, since use-package-verbose already has the possible value of debug.
The ordering of several elements of use-package-keywords have changed; if you had previously customized this (or were an extension author adding to this list), you may need to rework your changes.
For extension authors, :commands should no longer be propagated down for autoloading. See more below.

Other changes

Upgrade license to GPL 3.
If use-package-verbose is set to the symbol debug, any evaluation errors during package configuration will cause a complete report to be written to a *use-package* buffer, including: the text of the error, the use-package declaration that caused the error, the post-normalized form of this declaration, and the macro-expanded version (without verbosity-related code). Note that this still does not help if there are parsing errors, which cause Emacs to register a Lisp error at startup time.
New customization variable use-package-deferring-keywords, mainly intended for use by extension packages, indicates keywords that, if used without :demand, cause deferred loading (as if :defer t had been specified).
The :ensure keyword now accepts a specific pinning sub-keyword. For example:
```
(use-package foo
  :pin "elpa")
```
This ensure the package foo is installed from "elpa".
```
(use-package foo
  :ensure bar
  :ensure (quux :pin "melpa"))
```
This says that foo ensures that bar is installed, as well as quux from "melpa". It does not ensure that foo is installed, because explicit :ensure keywords were given.
New :hook keyword.
New :catch keyword. If t or nil, it enables (the default, see use-package-defaults) or disables catching errors at load time in use-package expansions. It can also be a function taking two arguments: the keyword being processed at the time the error was encountered, and the error object (as generated by condition-case).
New keywords :custom (foo1 bar1) (foo2 bar2) etc., and :custom-face.

NOTE: These are only for people who wish to keep customizations with their accompanying use-package declarations. Functionally, the only benefit over using setq in a :config block is that customizations might execute code when values are assigned. If you currently use M-x customize-option and save to a settings file, you do not want to use this option.
New :magic and :magic-fallback keywords.
New :defer-install keyword.
New customization variable use-package-enable-imenu-support.
New customization variable use-package-hook-name-suffix. Any symbols named in :hook, or in the CAR of cons cells passed to :hook, have this text appended to them as a convenience. If you find yourself using this keyword to add to hooks of different names, or just don't want such appending done, you can change the text to an empty string.
New customization variable use-package-compute-statistics, and an accompanying command M-x use-package-report. See the README for more details.
Allow :diminish to take no arguments.
Support multiple symbols passed to :after, and a mini-DSL using :all and :any.
:mode and :interpreter can now accept (rx ...) forms.
Using :load-path without also using :ensure now implies :ensure nil.
:bind (:map foo-map ...) now defers binding in the map until the package has been loaded.
Print key bindings for keymaps in describe-personal-keybindings.
When use-package-inject-hooks is non-nil, always fire :init and :config hooks.
Documentation added for the :after, :defer-install, :delight, :requires, :when and :unless keywords.
:requires SYM is subtly different from :if (featurep SYM), in that it happens before the :preface. This means that using :requires will cause definitions in the :preface to not be visible to the byte-compiler, leading to possible warnings about unknown functions, or functions that may not be available at run-time (which can generally be ignored, since :requires is intended as a check for basic system functionality; :after should be used to check for the presence of other modules).
New undocumented (and currently experimental) keyword :load may be used to change the name of the actual package loaded, rather than the package name, and may even add other names. For example: (use-package auctex :load tex-site). This keyword is used internally to generate the require for a package, so that deferral is simply a matter of not generating this keyword.
The source code is now broken into several files, so that certain optional features (diminish, delight, ensure) may be maintained separately from the core functionality.
When using the :after keyword, now even autoloadeds keybinding are deferred until after that other package has loaded, in order to allow convenient :bind to maps only present in that other package. Consider the following:
```
(use-package helm-descbinds
  :load-path "site-lisp/helm-descbinds"
  :after helm
  :bind ("C-h b" . helm-descbinds)
  :init
  (fset 'describe-bindings 'helm-descbinds))
```
The binding of C-h b here will not occur until helm is loaded; and after it is loaded, helm-descbinds itself is not loaded until the user presses C-h b.
For extension authors, if you add a keyword to use-package-keywords whose presence should indicate deferred loading, please also add it to use-package-deferring-keywords. Note that this is a bit of a sledgehammer, in that the mere presence of these keywords implies deferred loading. For a more subtle approach, see the new use-package-autoloads/<KEYWORD> support mentioned in the next bullet.
For extension authors, if you wish deferred loading to possibly occur, create functions named use-package-autoloads/<KEYWORD> for each keyword that you define, returning an alist of the form (SYMBOL . TYPE) of symbols to be autoloaded. SYMBOL should be an interactive function, and TYPE the smybol command, but this functionality may be extended in future. These autoloads are established if deferred loading is to happen.
If you specify a lambda form rather than a function symbol in any of the constructs that might introduce autoloads: :bind, :bind*, :interpreter, :mode, :magic, :magic-fallback, and :hook: then deferred loading will no longer be implied, since there's nothing to associate an autoload with that could later load the module. In these cases, it will be as if you'd specified :demand t, in order to ensure the lambda form is able to execute in the context of the loaded package.
For extension authors, there is a new customization variable use-package-merge-key-alist that specifies how values passed to multiple occurences of the same key should be merged into a single value, during normalization of the use-package declaration into a proper plist. The default behavior is to simply append the values together (since they are always normalized to lists).

Bug fixes

Repeating a bind no longer causes duplicates in personal-keybindings.
When byte-compiling, correctly output declare-function directives.
Append to use-package when debugging, don't clear it.
Don't allow :commands, :bind, etc., to be given an empty list.
Explicit :defer t should override use-package-always-demand.