Rework CONTRIBUTING guidelines

Give better recommendations for contributors on how to propose start the
work, write commit messages, and handle review by explicitly stating
expectations, however make it clear that maintainers will help you if
you have issues.

Write down the guidelines for maintainers on how they should handle
contributions and interact with other maintainers to help maintaining
good code quality level by listing maintainers responsibilities and
providing suggestions on how to handle various situations.

CONTRIBUTING.md

@@ -1,57 +1,169 @@
-# Winit Contributing Guidelines
+# Contribution Guidelines
 
-## Scope
-[See `FEATURES.md`](./FEATURES.md). When requesting or implementing a new Winit feature, you should
-consider whether or not it's directly related to window creation or input handling. If it isn't, it
-may be worth creating a separate crate that extends Winit's API to add that functionality.
+This document contains guidelines for contributing code to winit. It has to be
+followed in order for your patch to be approved and applied.
 
+## Contributing
 
-## Reporting an issue
+Anyone can contribute to winit, however given that it's a cross platform
+windowing toolkit getting certain changes incorporated upstream could be
+challenging.
 
-When reporting an issue, in order to help the maintainers understand what the problem is, please make
-your description of the issue as detailed as possible:
+To save your time it's wise to check already opened [pull requests][prs] and
+[issues][issues]. In general, bug fixes and missing implementations are always
+accepted, however new API proposals should go into the issue first. When in
+doubt contact us on [matrix][matrix] or via opening an issue.
 
-- if it is a bug, please provide a clear explanation of what happens, what should happen, and how to
-  reproduce the issue, ideally by providing a minimal program exhibiting the problem
-- if it is a feature request, please provide a clear argumentation about why you believe this feature
-  should be supported by winit
+### Submitting your work and handling review
 
-## Making a pull request
+All patches have to be sent on Github as [pull requests][prs]. To simplify your
+life during review it's recommended to check the "give contributors write access
+to the branch" checkbox.
 
-When making a code contribution to winit, before opening your pull request, please make sure that:
+#### Creating commits
 
-- your patch builds with Winit's minimal supported rust version - Rust 1.70.
-- you tested your modifications on all the platforms impacted, or if not possible, detail which platforms
-  were not tested, and what should be tested, so that a maintainer or another contributor can test them
-- you updated any relevant documentation in winit
-- you left comments in your code explaining any part that is not straightforward, so that the
-  maintainers and future contributors don't have to try to guess what your code is supposed to do
-- your PR adds an entry to the changelog file if the introduced change is relevant to winit users.
+When creating a commit, follow these general rules:
+  - Try to limit the first line (title) of the commit message to 50 characters,
+    but not more than 60 characters.
+  - The commit starts with an uppercase latter and everything else must be
+    lowercase, unless you quote a symbol, like `Window`.
+  - Use the body of the commit message to actually explain what your patch does
+    and why it is useful. Even if your patch is a one line fix, the description
+    is not limited in length and may span over multiple paragraphs. Use proper
+    English syntax, grammar and punctuation. The body is generally wrapped
+    at 72 characters.
+  - If you're a downstream user and your fixing your issue, consider to link it
+    like `Links: URL` in the end of the commit message.
+  - Try to address only one issue/topic per commit.
+  - Prefer describing your changes in imperative mood, e.g. *"make xyzzy do
+    frotz"* instead of *"[This patch] makes xyzzy do frotz"* or *"[I] changed
+    xyzzy to do frotz"*, as if you are giving orders to the codebase to change
+    its behaviour.
+  - When fixing an issue from https://github.com/rust-windowing/winit/issues,
+    ensure to have it include in the end of the commit. See other commits
+    on how it's done.
+  - When in doubt, follow the format and layout of the recent existing commits.
 
-  You needn't worry about the added entry causing conflicts, the maintainer that merges the PR will
-  handle those for you when merging (see below).
-- if your PR affects the platform compatibility of one or more features or adds another feature, the
-  relevant sections in [`FEATURES.md`](https://github.com/rust-windowing/winit/blob/master/FEATURES.md#features)
-  should be updated.
+The maintainers will fixup your commit message when applying the patch, but it's
+still recommended to follow the rules above to make the life of maintainers
+easier.
 
-Once your PR is open, you can ask for a review by a maintainer of your platform. Winit's merging policy
-is that a PR must be approved by at least two maintainers of winit before being merged, including
-at least a maintainer of the platform (a maintainer making a PR themselves counts as approving it).
+If you want to communicate something to reviewers, but it doesn't belong to
+the commit message, write that under `--` on PR body. Your PR could look like:
 
-Once your PR is deemed ready, the merging maintainer will take care of resolving conflicts in
-`CHANGELOG.md` (but you must resolve other conflicts yourself). Doing this requires that you check the
-"give contributors write access to the branch" checkbox when creating the PR.
+  ```
+  TITLE (matches commit title)
+
+  Body (matches commit body)
+
+  --
+
+  Your arbitrary message goes here.
+
+  Various checkboxes PR template required you to fill.
+  ```
+
+#### Handling review
+
+During the review process certain events could require an action from your side,
+to communication more efficient the common patterns and reactions are described
+below.
+
+_Event:_ The CI fails to build, but it looks like not your fault. Not
+communicating so, could result into maintainers not looking into your patch,
+unless they CI that CI pass.\
+_Desired behavior:_ Write a message saying roughly the following "The CI failure
+is unrelated", so maintainers will fix it for you.
+
+_Event:_ Collaborator requested review on your PR.\
+_Desired behavior:_ Once you address the request, you _should_ re-request review
+with the github's UI. If you don't agree with what maintainer suggested, you
+should object that and re-request the review. That will indicate that the
+_ball_ is on maintainer's side.
+
+_Event:_ You've opened a PR, but maintainer shortly after commented that they
+want to work on that _themselves_.\
+_Desired behavior:_ Discusses with maintainer their plans if they were not
+outlined in the initial response, because such response means that they
+are not interested in reviewing your code. Such thing could happen when
+underestimating complexity of the task you're solving or when your patch
+mandate certain downstream designs.
+
+[prs]: https://github.com/rust-windowing/winit/pulls
+[issues]: https://github.com/rust-windowing/winit/issues
+[matrix]: https://matrix.to/#/#rust-windowing:matrix.org
 
 ## Maintainers
 
-The current maintainers for each platform are listed in the [CODEOWNERS](.github/CODEOWNERS) file.
+Winit has plenty of maintainers with different backgrounds, experience level,
+and reasons to be winit maintainer in the first place. To ensure that winit's
+code quality is not decreasing over time and to make it easier to teach new
+maintainers the _winit way of doing things_ the common policies and routines
+are defined in this section.
 
-## Release process
+The current maintainers for each platform are listed in [this file][CODEOWNERS].
+
+### Contributions handling
+
+The maintainer must ensure that the external contributions meet the winit's
+quality standards. If it's not, it **is maintainer's responsibility** to bring
+it on par, which includes:
+
+  - Decline the patch if it tries to achieve short term goals instead of solving
+    the problem in general. In such case maintainer must communicate that **as
+    early as possible**, so contributors don't spend their time on something
+    that won't be accepted in the end.
+  - Ensure that formatting is consistent and `CHANGELOG` messages are clear
+    for the end users.
+  - Improve the commit message, so it'll be easier for other maintainers to
+    understand the motivation without going through all the discussions on the
+    particular patch/PR.
+  - Ensure that the proposed patch doesn't break platform parity. If the
+    breakage is desired by contributor, an issue should be opened to discuss
+    with other maintainers before merging.
+  - Always fix CI issues before merging if they don't originate from the
+    submitted work.
+
+However, maintainer must always give a leeway for external contributors, so they
+don't feel discouraged contributing, for example:
+
+  - Suggest a patch to resolve style issues, if it's the only issue with the
+    submitted work. Keep in mind that pushing the resolution yourself is not
+    desired, because contributor might not agree with what you did.
+  - Be more explicit on how things should be done if you doesn't like the
+    approach.
+  - Suggest to finish PR for them if they're absent for a while and you need the
+    proposed changes to move forward with something. In such case maintainer
+    must preserve attribution with `Co-authored-by`, `Suggested-by`, or keep
+    the original commiter.
+  - Rebase their work for them when massive changes to winit codebase were
+    introduced.
+
+When reviewing code of other maintainers all of the above is on the maintainer
+who submitted the patch. Interested maintainers could help push the work over
+the finish line, but teaching other maintainers should be preferred.
+
+When contributor is _regular_ in winit, the maintainer should slowly start
+requiring contributor to match *maintainer* quality standards when writing
+patches and commit messages.
+
+### Contributing
+
+When submitting a patch maintainer should follow the general contributing
+guidelines, however all soft rules (e.g `Try to`), become strict.
+
+To make life simpler for other maintainers it's suggested to create your branch
+under the project repository instead of your own fork. The naming scheme is
+`github_user_name/branch_name`. Doing so will make your work easier to rebase
+for other maintainers when you're absent.
+
+### Release process
 
 Given that winit is a widely used library, we should be able to make a patch
 releases at any time we want without blocking the development of new features.
 
-To achieve these goals, a new branch is created for every new release. Releases and later patch releases are committed and tagged in this branch.
+To achieve these goals, a new branch is created for every new release. Releases
+and later patch releases are committed and tagged in this branch.
 
 The exact steps for an exemplary `0.2.0` release might look like this:
   1. Initially, the version on the latest master is `0.1.0`
@@ -67,3 +179,5 @@ When doing a patch release, the process is similar:
   2. Checkout the `v0.2.x` branch
   3. Cherry-pick the required non-breaking changes into the `v0.2.x`
   4. Follow steps 3-7 of the regular release example
+
+[CODEOWNERS]: .github/CODEOWNERS