Move syncing doc to book

3 files changed, 126 insertions, 125 deletions

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 6ab2bd59137..85eb82a646c 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -21,11 +21,6 @@ All contributors are expected to follow the [Rust Code of Conduct].
     - [IntelliJ Rust](#intellij-rust)
     - [Rust Analyzer](#rust-analyzer)
   - [How Clippy works](#how-clippy-works)
-  - [Syncing changes between Clippy and `rust-lang/rust`](#syncing-changes-between-clippy-and-rust-langrust)
-    - [Patching git-subtree to work with big repos](#patching-git-subtree-to-work-with-big-repos)
-    - [Performing the sync from `rust-lang/rust` to Clippy](#performing-the-sync-from-rust-langrust-to-clippy)
-    - [Performing the sync from Clippy to `rust-lang/rust`](#performing-the-sync-from-clippy-to-rust-langrust)
-    - [Defining remotes](#defining-remotes)
   - [Issue and PR triage](#issue-and-pr-triage)
   - [Bors and Homu](#bors-and-homu)
   - [Contributions](#contributions)
@@ -205,126 +200,6 @@ 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
 
-## Syncing changes between Clippy and [`rust-lang/rust`]
-
-Clippy currently gets built with a pinned nightly version.
-
-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.
-
-We need to sync these changes back to this repository periodically, and the changes
-made to this repository in the meantime also need to be synced to the `rust-lang/rust` repository.
-
-To avoid flooding the `rust-lang/rust` PR queue, this two-way sync process is done
-in a bi-weekly basis if there's no urgent changes. This is done starting on the day of
-the Rust stable release and then every other week. That way we guarantee that we keep
-this repo up to date with the latest compiler API, and every feature in Clippy is available
-for 2 weeks in nightly, before it can get to beta. For reference, the first sync
-following this cadence was performed the 2020-08-27.
-
-This process is described in detail in the following sections. For general information
-about `subtree`s in the Rust repository see [Rust's `CONTRIBUTING.md`][subtree].
-
-### Patching git-subtree to work with big repos
-
-Currently, there's a bug in `git-subtree` that prevents it from working properly
-with the [`rust-lang/rust`] repo. There's an open PR to fix that, but it's stale.
-Before continuing with the following steps, we need to manually apply that fix to
-our local copy of `git-subtree`.
-
-You can get the patched version of `git-subtree` from [here][gitgitgadget-pr].
-Put this file under `/usr/lib/git-core` (taking a backup of the previous file)
-and make sure it has the proper permissions:
-
-```bash
-sudo cp --backup /path/to/patched/git-subtree.sh /usr/lib/git-core/git-subtree
-sudo chmod --reference=/usr/lib/git-core/git-subtree~ /usr/lib/git-core/git-subtree
-sudo chown --reference=/usr/lib/git-core/git-subtree~ /usr/lib/git-core/git-subtree
-```
-
-_Note:_ The first time running `git subtree push` a cache has to be built. This
-involves going through the complete Clippy history once. For this you have to
-increase the stack limit though, which you can do with `ulimit -s 60000`.
-Make sure to run the `ulimit` command from the same session you call git subtree.
-
-_Note:_ If you are a Debian user, `dash` is the shell used by default for scripts instead of `sh`.
-This shell has a hardcoded recursion limit set to 1000. In order to make this process work,
-you need to force the script to run `bash` instead. You can do this by editing the first
-line of the `git-subtree` script and changing `sh` to `bash`.
-
-### Performing the sync from [`rust-lang/rust`] to Clippy
-
-Here is a TL;DR version of the sync process (all of the following commands have
-to be run inside the `rust` directory):
-
-1. Clone the [`rust-lang/rust`] repository or make sure it is up to date.
-2. Checkout the commit from the latest available nightly. You can get it using `rustup check`.
-3. Sync the changes to the rust-copy of Clippy to your Clippy fork:
-    ```bash
-    # Make sure to change `your-github-name` to your github name in the following command. Also be
-    # sure to either use a net-new branch, e.g. `sync-from-rust`, or delete the branch beforehand
-    # because changes cannot be fast forwarded
-    git subtree push -P src/tools/clippy git@github.com:your-github-name/rust-clippy sync-from-rust
-    ```
-
-    _Note:_ This will directly push to the remote repository. You can also push
-    to your local copy by replacing the remote address with `/path/to/rust-clippy`
-    directory.
-
-    _Note:_ Most of the time you have to create a merge commit in the
-    `rust-clippy` repo (this has to be done in the Clippy repo, not in the
-    rust-copy of Clippy):
-    ```bash
-    git fetch origin && git fetch upstream
-    git checkout sync-from-rust
-    git merge upstream/master
-    ```
-4. Open a PR to `rust-lang/rust-clippy` and wait for it to get merged (to
-   accelerate the process ping the `@rust-lang/clippy` team in your PR and/or
-   ~~annoy~~ ask them in the [Zulip] stream.)
-
-### Performing the sync from Clippy to [`rust-lang/rust`]
-
-All of the following commands have to be run inside the `rust` directory.
-
-1. Make sure Clippy itself is up-to-date by following the steps outlined in the previous
-section if necessary.
-
-2. Sync the `rust-lang/rust-clippy` master to the rust-copy of Clippy:
-    ```bash
-    git checkout -b sync-from-clippy
-    git subtree pull -P src/tools/clippy https://github.com/rust-lang/rust-clippy master
-    ```
-3. Open a PR to [`rust-lang/rust`]
-
-### Defining remotes
-
-You may want to define remotes, so you don't have to type out the remote
-addresses on every sync. You can do this with the following commands (these
-commands still have to be run inside the `rust` directory):
-
-```bash
-# Set clippy-upstream remote for pulls
-$ git remote add clippy-upstream https://github.com/rust-lang/rust-clippy
-# Make sure to not push to the upstream repo
-$ git remote set-url --push clippy-upstream DISABLED
-# Set clippy-origin remote to your fork for pushes
-$ git remote add clippy-origin git@github.com:your-github-name/rust-clippy
-# Set a local remote
-$ git remote add clippy-local /path/to/rust-clippy
-```
-
-You can then sync with the remote names from above, e.g.:
-
-```bash
-$ git subtree push -P src/tools/clippy clippy-local sync-from-rust
-```
-
-[gitgitgadget-pr]: https://github.com/gitgitgadget/git/pull/493
-[subtree]: https://rustc-dev-guide.rust-lang.org/contributing.html#external-dependencies-subtree
-[`rust-lang/rust`]: https://github.com/rust-lang/rust
-
 ## Issue and PR triage
 
 Clippy is following the [Rust triage procedure][triage] for issues and pull
diff --git a/book/src/SUMMARY.md b/book/src/SUMMARY.md
index 5d10101d637..200b0cb29ff 100644
--- a/book/src/SUMMARY.md
+++ b/book/src/SUMMARY.md
@@ -22,6 +22,7 @@
     - [Adding Lints](development/adding_lints.md)
     - [Common Tools](development/common_tools_writing_lints.md)
 - [Infrastructure](infrastructure/README.md)
+    - [Syncing changes between Clippy and rust-lang/rust](infrastructure/sync.md)
     - [Backporting Changes](infrastructure/backport.md)
     - [Updating the Changelog](infrastructure/changelog_update.md)
     - [Release a New Version](infrastructure/release.md)
diff --git a/book/src/infrastructure/sync.md b/book/src/infrastructure/sync.md
new file mode 100644
index 00000000000..981e63cfdda
--- /dev/null
+++ b/book/src/infrastructure/sync.md
@@ -0,0 +1,125 @@
+# Syncing changes between Clippy and [`rust-lang/rust`]
+
+Clippy currently gets built with a pinned nightly version.
+
+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.
+
+We need to sync these changes back to this repository periodically, and the
+changes made to this repository in the meantime also need to be synced to the
+`rust-lang/rust` repository.
+
+To avoid flooding the `rust-lang/rust` PR queue, this two-way sync process is
+done in a bi-weekly basis if there's no urgent changes. This is done starting on
+the day of the Rust stable release and then every other week. That way we
+guarantee that we keep this repo up to date with the latest compiler API, and
+every feature in Clippy is available for 2 weeks in nightly, before it can get
+to beta. For reference, the first sync following this cadence was performed the
+2020-08-27.
+
+This process is described in detail in the following sections. For general
+information about `subtree`s in the Rust repository see [Rust's
+`CONTRIBUTING.md`][subtree].
+
+## Patching git-subtree to work with big repos
+
+Currently, there's a bug in `git-subtree` that prevents it from working properly
+with the [`rust-lang/rust`] repo. There's an open PR to fix that, but it's
+stale. Before continuing with the following steps, we need to manually apply
+that fix to our local copy of `git-subtree`.
+
+You can get the patched version of `git-subtree` from [here][gitgitgadget-pr].
+Put this file under `/usr/lib/git-core` (making a backup of the previous file)
+and make sure it has the proper permissions:
+
+```bash
+sudo cp --backup /path/to/patched/git-subtree.sh /usr/lib/git-core/git-subtree
+sudo chmod --reference=/usr/lib/git-core/git-subtree~ /usr/lib/git-core/git-subtree
+sudo chown --reference=/usr/lib/git-core/git-subtree~ /usr/lib/git-core/git-subtree
+```
+
+> _Note:_ The first time running `git subtree push` a cache has to be built.
+> This involves going through the complete Clippy history once. For this you
+> have to increase the stack limit though, which you can do with `ulimit -s
+> 60000`. Make sure to run the `ulimit` command from the same session you call
+> git subtree.
+
+> _Note:_ If you are a Debian user, `dash` is the shell used by default for
+> scripts instead of `sh`. This shell has a hardcoded recursion limit set to
+> 1000. In order to make this process work, you need to force the script to run
+> `bash` instead. You can do this by editing the first line of the `git-subtree`
+> script and changing `sh` to `bash`.
+
+## Performing the sync from [`rust-lang/rust`] to Clippy
+
+Here is a TL;DR version of the sync process (all of the following commands have
+to be run inside the `rust` directory):
+
+1. Clone the [`rust-lang/rust`] repository or make sure it is up to date.
+2. Checkout the commit from the latest available nightly. You can get it using
+   `rustup check`.
+3. Sync the changes to the rust-copy of Clippy to your Clippy fork:
+    ```bash
+    # Make sure to change `your-github-name` to your github name in the following command. Also be
+    # sure to either use a net-new branch, e.g. `sync-from-rust`, or delete the branch beforehand
+    # because changes cannot be fast forwarded and you have to run this command again.
+    git subtree push -P src/tools/clippy git@github.com:your-github-name/rust-clippy sync-from-rust
+    ```
+
+    > _Note:_ This will directly push to the remote repository. You can also
+    > push to your local copy by replacing the remote address with
+    > `/path/to/rust-clippy` directory.
+
+    > _Note:_ Most of the time you have to create a merge commit in the
+    > `rust-clippy` repo (this has to be done in the Clippy repo, not in the
+    > rust-copy of Clippy):
+    ```bash
+    git fetch upstream  # assuming upstream is the rust-lang/rust remote
+    git checkout sync-from-rust
+    git merge upstream/master
+    ```
+4. Open a PR to `rust-lang/rust-clippy` and wait for it to get merged (to
+   accelerate the process ping the `@rust-lang/clippy` team in your PR and/or
+   ask them in the [Zulip] stream.)
+
+[Zulip]: https://rust-lang.zulipchat.com/#narrow/stream/clippy
+
+## Performing the sync from Clippy to [`rust-lang/rust`]
+
+All of the following commands have to be run inside the `rust` directory.
+
+1. Make sure you have checked out the latest `master` of `rust-lang/rust`.
+2. Sync the `rust-lang/rust-clippy` master to the rust-copy of Clippy:
+    ```bash
+    git checkout -b sync-from-clippy
+    git subtree pull -P src/tools/clippy https://github.com/rust-lang/rust-clippy master
+    ```
+3. Open a PR to [`rust-lang/rust`]
+
+## Defining remotes
+
+You may want to define remotes, so you don't have to type out the remote
+addresses on every sync. You can do this with the following commands (these
+commands still have to be run inside the `rust` directory):
+
+```bash
+# Set clippy-upstream remote for pulls
+$ git remote add clippy-upstream https://github.com/rust-lang/rust-clippy
+# Make sure to not push to the upstream repo
+$ git remote set-url --push clippy-upstream DISABLED
+# Set clippy-origin remote to your fork for pushes
+$ git remote add clippy-origin git@github.com:your-github-name/rust-clippy
+# Set a local remote
+$ git remote add clippy-local /path/to/rust-clippy
+```
+
+You can then sync with the remote names from above, e.g.:
+
+```bash
+$ git subtree push -P src/tools/clippy clippy-local sync-from-rust
+```
+
+[gitgitgadget-pr]: https://github.com/gitgitgadget/git/pull/493
+[subtree]: https://rustc-dev-guide.rust-lang.org/contributing.html#external-dependencies-subtree
+[`rust-lang/rust`]: https://github.com/rust-lang/rust