Pin Clippy to a nightly

.github/workflows/clippy.yml

@@ -56,9 +56,6 @@ jobs:
         restore-keys: |
           ${{ runner.os }}-x86_64-unknown-linux-gnu
 
-    - name: Master Toolchain Setup
-      run: bash setup-toolchain.sh
-
     # Run
     - name: Set LD_LIBRARY_PATH (Linux)
       run: |

.github/workflows/clippy_bors.yml

@@ -105,11 +105,6 @@ jobs:
         restore-keys: |
           ${{ runner.os }}-${{ matrix.host }}
 
-    - name: Master Toolchain Setup
-      run: bash setup-toolchain.sh
-      env:
-        HOST_TOOLCHAIN: ${{ matrix.host }}
-
     # Run
     - name: Set LD_LIBRARY_PATH (Linux)
       if: runner.os == 'Linux'
@@ -192,9 +187,6 @@ jobs:
         restore-keys: |
           ${{ runner.os }}-x86_64-unknown-linux-gnu
 
-    - name: Master Toolchain Setup
-      run: bash setup-toolchain.sh
-
     # Run
     - name: Build Integration Test
       run: cargo test --test integration --features integration --no-run
@@ -273,9 +265,6 @@ jobs:
         restore-keys: |
           ${{ runner.os }}-x86_64-unknown-linux-gnu
 
-    - name: Master Toolchain Setup
-      run: bash setup-toolchain.sh
-
     # Download
     - name: Download target dir
       uses: actions/download-artifact@v1

CONTRIBUTING.md

@@ -182,18 +182,21 @@ That's why the `else_if_without_else` example uses the `register_early_pass` fun
 [early_lint_pass]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_lint/trait.EarlyLintPass.html
 [late_lint_pass]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_lint/trait.LateLintPass.html
 
-## Fixing build failures caused by Rust
+## Syncing changes from [`rust-lang/rust`] to Clippy
 
-Clippy currently gets built with `rustc` of the `rust-lang/rust` `master`
-branch. Most of the times we have to adapt to the changes and only very rarely
-there's an actual bug in Rust.
+Clippy currently gets built with a pinned nightly version.
 
-If you decide to make Clippy work again with a Rust commit that breaks it, you
-have to sync the `rust-lang/rust-clippy` repository with the `subtree` copy of
-Clippy in the `rust-lang/rust` repository.
+In the `rust-lang/rust` repository, where rustc resides, there's a copy of Clippy
+that compiler hackers modify from time to time to adapt to changes in the unstable
+API of the compiler.
 
-For general information about `subtree`s in the Rust repository see [Rust's
-`CONTRIBUTING.md`][subtree].
+We need to sync these changes back to this repository periodically. If you want
+to help with that, you have to sync the `rust-lang/rust-clippy` repository with 
+the `subtree` copy of Clippy in the `rust-lang/rust` repository, and update
+the `rustc-toolchain` file accordingly.
+
+For general information about `subtree`s in the Rust repository
+see [Rust's `CONTRIBUTING.md`][subtree].
 
 ### Patching git-subtree to work with big repos
 

doc/basics.md

@@ -1,16 +1,14 @@
 # Basics for hacking on Clippy
 
 This document explains the basics for hacking on Clippy. Besides others, this
-includes how to set-up the development environment, how to build and how to test
-Clippy. For a more in depth description on the codebase take a look at [Adding
-Lints] or [Common Tools].
+includes how to build and test Clippy. For a more in depth description on
+the codebase take a look at [Adding Lints] or [Common Tools].
 
 [Adding Lints]: https://github.com/rust-lang/rust-clippy/blob/master/doc/adding_lints.md
 [Common Tools]: https://github.com/rust-lang/rust-clippy/blob/master/doc/common_tools_writing_lints.md
 
 - [Basics for hacking on Clippy](#basics-for-hacking-on-clippy)
   - [Get the code](#get-the-code)
-  - [Setup](#setup)
   - [Building and Testing](#building-and-testing)
   - [`cargo dev`](#cargo-dev)
   - [PR](#pr)
@@ -38,29 +36,9 @@ git rebase upstream/master
 git push
 ```
 
-## Setup
-
-Next we need to setup the toolchain to compile Clippy. Since Clippy heavily
-relies on compiler internals it is build with the latest rustc master. To get
-this toolchain, you can just use the `setup-toolchain.sh` script or use
-`rustup-toolchain-install-master`:
-
-```bash
-bash setup-toolchain.sh
-# OR
-cargo install rustup-toolchain-install-master
-# For better IDE integration also add `-c rustfmt -c rust-src` (optional)
-rustup-toolchain-install-master -f -n master -c rustc-dev -c llvm-tools
-rustup override set master
-```
-
-_Note:_ Sometimes you may get compiler errors when building Clippy, even if you
-didn't change anything. Normally those will be fixed by a maintainer in a few hours. 
-
 ## Building and Testing
 
-Once the `master` toolchain is installed, you can build and test Clippy like
-every other Rust project:
+You can build and test Clippy like every other Rust project:
 
 ```bash
 cargo build  # builds Clippy

rust-toolchain

@@ -1 +1,3 @@
-nightly
+[toolchain]
+channel = "nightly-2020-11-29"
+components = ["llvm-tools-preview", "rustc-dev", "rust-src", "rustfmt"]