Merge pull request #979 from ehuss/rls-deprecation

Post about RLS deprecation.

Author: rylev

posts/2022-07-01-RLS-deprecation.md

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+---
+layout: post
+title: "RLS Deprecation"
+author: The Rust Dev Tools Team
+---
+
+The Rust Language Server (RLS) is being deprecated in favor of [rust-analyzer](https://rust-analyzer.github.io/).
+Current users of RLS should migrate to using rust-analyzer instead.
+Builds of RLS will continue to be released until at least the Rust 1.64 release (2022-09-22), after which no new releases will be made.
+This timeline may change if any issues arise.
+
+RLS is an implementation of the [Language Server Protocol](https://microsoft.github.io/language-server-protocol/) (LSP) which provides enhanced features with any editor that supports the protocol, such as code-checking and refactoring.
+RLS was introduced by [RFC 1317](https://rust-lang.github.io/rfcs/1317-ide.html) and development was very active from 2016 through 2019.
+However, the architecture of RLS has several limitations that can make it difficult to provide low-latency and high-quality responses needed for an interactive environment.
+
+Development of rust-analyzer began near the beginning of 2018 to provide an alternate LSP implementation for Rust.
+rust-analyzer uses a fundamentally different approach that does not rely on using `rustc`.
+In [RFC 2912](https://rust-lang.github.io/rfcs/2912-rust-analyzer.html) rust-analyzer was adopted as the official replacement for RLS.
+
+How you migrate to rust-analyzer will depend on which editor you are using.
+If you are using VSCode, you should uninstall the `rust-lang.rust` extension and install the official [`rust-lang.rust-analyzer` extension](https://marketplace.visualstudio.com/items?itemName=rust-lang.rust-analyzer).
+For other editors, please consult the [rust-analyzer manual](https://rust-analyzer.github.io/manual.html) for instructions on how to install it.
+
+Should you have any issues migrating to rust-analyzer, the [Editors and IDEs category](https://users.rust-lang.org/c/ide/14) on the Rust Users forum is available for help with installation and usage.
+
+We will soon be marking the official `rust-lang.rust` VSCode extension as deprecated, and will be implementing notifications that will inform users about the transition.
+After the end of release builds of RLS, we plan to replace the `rls` executable in official Rust releases with a small LSP implementation that informs the user that RLS is no longer available.
+
+We would like to thank everyone who has worked on RLS and rust-analyzer.
+These options would not exist without the tremendous effort of all the contributors to these projects.