Update book and templates with feature freeze

.github/ISSUE_TEMPLATE/new_lint.yml

@@ -1,5 +1,7 @@
 name: New lint suggestion
-description: Suggest a new Clippy lint.
+description: |
+  Suggest a new Clippy lint (currently not accepting new lints)
+  Check out the Clippy book for more information about the feature freeze.
 labels: ["A-lint"]
 body:
   - type: markdown

.github/PULL_REQUEST_TEMPLATE.md

@@ -32,6 +32,10 @@ order to get feedback.
 
 Delete this line and everything above before opening your PR.
 
+Note taht we are currently not taking in new PRs that add new lints. We are in a
+feature freeze. Check out the book for more information. If you open a
+feature-adding pull request, its review will be delayed.
+
 ---
 
 *Please write a short comment explaining your change (or "none" for internal only changes)*

book/src/README.md

@@ -1,5 +1,9 @@
 # Clippy
 
+[### IMPORTANT NOTE FOR CONTRIBUTORS ================](development/feature_freeze.md)
+
+----
+
 [![License: MIT OR Apache-2.0](https://img.shields.io/crates/l/clippy.svg)](https://github.com/rust-lang/rust-clippy#license)
 
 A collection of lints to catch common mistakes and improve your

book/src/SUMMARY.md

@@ -13,6 +13,7 @@
     - [GitLab CI](continuous_integration/gitlab.md)
     - [Travis CI](continuous_integration/travis.md)
 - [Development](development/README.md)
+    - [IMPORTANT: FEATURE FREEZE](development/feature_freeze.md)
     - [Basics](development/basics.md)
     - [Adding Lints](development/adding_lints.md)
     - [Defining Lints](development/defining_lints.md)

book/src/development/adding_lints.md

@@ -1,5 +1,8 @@
 # Adding a new lint
 
+[### IMPORTANT NOTE FOR CONTRIBUTORS ================](feature_freeze.md)
+
+
 You are probably here because you want to add a new lint to Clippy. If this is
 the first time you're contributing to Clippy, this document guides you through
 creating an example lint from scratch.

book/src/development/feature_freeze.md

@@ -0,0 +1,50 @@
+# IMPORTANT: FEATURE FREEZE
+
+This is a temporary notice.
+
+From May 9th, 2025 until the 1st of August, 2025 we will perform a feature freeze. Only bugfix PRs will be reviewed with the
+exception of already open ones. Every feature-adding PR open in between those dates will be moved into a milestone
+to be reviewed separately at another time.
+
+We do this because of the long backlog of bugs that need to be addressed
+in order to contiue being the state of the art linter that Clippy has become known for being.
+
+## For contributors
+
+If you are a contributor or are planning to become one, **please do not open a lint-adding PR**, we have lots of open bugs
+of all levels of difficulty that you can address instead!
+
+We currently have about 800 lints, each one posing a maintainability challenge that needs to account to every possible
+usecase of the whole ecosystem. Bugs are natural in every software, but the Clippy team considers that Clippy needs a
+refinement period.
+
+If you open a PR at this time, we will not review it but push it into a milestone until the refinement period ends,
+adding additional load into our reviewing schedules.
+
+## I want to help, what can I do
+
+Thanks a lot to everyone who wants to help Clippy become better software in this feature freeze period!
+If you'd like to help, making a bugfix, making sure that it works, and opening a PR is a great step!
+
+As a general metric and always taking into account your skill and knowledge level, you can use this guide:
+
+- 🟥 [ICEs][search_ice], these are compiler errors that causes Clippy to panic and crash. Usually involves high-level debugging,
+sometimes interacting directly with the upstream compiler. Difficult to fix but a great challenge that improves
+a lot developer workflows!
+
+- 🟧 [Suggestion causes bug][sugg_causes_bug], Clippy suggested code that changed logic in some silent way. Unacceptable, as this may have
+disastreous consequences. Easier to fix than ICEs
+
+- 🟨 [Suggestion causes error][sugg_causes_error], Clippy suggested code snippet that caused a compiler error when applied.
+We need to make sure that Clippy doesn't suggest using a variable twice at the same time or similar
+easy-to-happen occurrences.
+
+- 🟩 [False positives][false_positive], a lint should not have fired, the easiest of them all, as this is "just" identifying the root of a
+the false positive and making an exception for those cases.
+
+Note that false negatives do not have priority unless the case is very clear, as they are a feature-request in a trench coat.
+
+[search_ice]: https://github.com/rust-lang/rust-clippy/issues?q=sort%3Aupdated-desc+state%3Aopen+label%3A%22I-ICE%22
+[sugg_causes_bug]: https://github.com/rust-lang/rust-clippy/issues?q=sort%3Aupdated-desc%20state%3Aopen%20label%3AI-suggestion-causes-bug
+[sugg_causes_error]: https://github.com/rust-lang/rust-clippy/issues?q=sort%3Aupdated-desc%20state%3Aopen%20label%3AI-suggestion-causes-error%20
+[false_positive]: https://github.com/rust-lang/rust-clippy/issues?q=sort%3Aupdated-desc%20state%3Aopen%20label%3AI-false-positive