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| <h1 id="using-external-repositories"><a class="header" href="#using-external-repositories">Using External Repositories</a></h1> |
| <p>The <code>rust-lang/rust</code> git repository depends on several other repos in the <code>rust-lang</code> organization. |
| There are three main ways we use dependencies:</p> |
| <ol> |
| <li>As a Cargo dependency through crates.io (e.g. <code>rustc-rayon</code>)</li> |
| <li>As a git (e.g. <code>clippy</code>) or a <a href="https://josh-project.github.io/josh/intro.html">josh</a> (e.g. <code>miri</code>) subtree</li> |
| <li>As a git submodule (e.g. <code>cargo</code>)</li> |
| </ol> |
| <p>As a general rule:</p> |
| <ul> |
| <li>Use crates.io for libraries that could be useful for others in the ecosystem</li> |
| <li>Use subtrees for tools that depend on compiler internals and need to be updated if there are breaking |
| changes</li> |
| <li>Use submodules for tools that are independent of the compiler</li> |
| </ul> |
| <h2 id="external-dependencies-subtrees"><a class="header" href="#external-dependencies-subtrees">External Dependencies (subtrees)</a></h2> |
| <p>The following external projects are managed using some form of a <code>subtree</code>:</p> |
| <ul> |
| <li><a href="https://github.com/rust-lang/rust-clippy">clippy</a></li> |
| <li><a href="https://github.com/rust-lang/miri">miri</a></li> |
| <li><a href="https://github.com/rust-lang/portable-simd">portable-simd</a></li> |
| <li><a href="https://github.com/rust-lang/rustfmt">rustfmt</a></li> |
| <li><a href="https://github.com/rust-lang/rust-analyzer">rust-analyzer</a></li> |
| <li><a href="https://github.com/rust-lang/rustc_codegen_cranelift">rustc_codegen_cranelift</a></li> |
| <li><a href="https://github.com/rust-lang/rustc-dev-guide">rustc-dev-guide</a></li> |
| <li><a href="https://github.com/rust-lang/compiler-builtins">compiler-builtins</a></li> |
| <li><a href="https://github.com/rust-lang/stdarch">stdarch</a></li> |
| </ul> |
| <p>In contrast to <code>submodule</code> dependencies |
| (see below for those), the <code>subtree</code> dependencies are just regular files and directories which can |
| be updated in tree. However, if possible, enhancements, bug fixes, etc. specific |
| to these tools should be filed against the tools directly in their respective |
| upstream repositories. The exception is that when rustc changes are required to |
| implement a new tool feature or test, that should happen in one collective rustc PR.</p> |
| <p><code>subtree</code> dependencies are currently managed by two distinct approaches:</p> |
| <ul> |
| <li>Using <code>git subtree</code> |
| <ul> |
| <li><code>clippy</code> (<a href="https://doc.rust-lang.org/nightly/clippy/development/infrastructure/sync.html#performing-the-sync-from-rust-langrust-to-clippy">sync guide</a>)</li> |
| <li><code>portable-simd</code> (<a href="https://github.com/rust-lang/portable-simd/blob/master/subtree-sync.sh">sync script</a>)</li> |
| <li><code>rustfmt</code></li> |
| <li><code>rustc_codegen_cranelift</code> (<a href="https://github.com/rust-lang/rustc_codegen_cranelift/blob/113af154d459e41b3dc2c5d7d878e3d3a8f33c69/scripts/rustup.sh#L7">sync script</a>)</li> |
| </ul> |
| </li> |
| <li>Using the <a href="#synchronizing-a-josh-subtree">josh</a> tool |
| <ul> |
| <li><code>miri</code></li> |
| <li><code>rust-analyzer</code></li> |
| <li><code>rustc-dev-guide</code></li> |
| <li><code>compiler-builtins</code></li> |
| <li><code>stdarch</code></li> |
| </ul> |
| </li> |
| </ul> |
| <h3 id="josh-subtrees"><a class="header" href="#josh-subtrees">Josh subtrees</a></h3> |
| <p>The <a href="https://josh-project.github.io/josh/intro.html">josh</a> tool is an alternative to git subtrees, which manages git history in a different way and scales better to larger repositories. Specific tooling is required to work with josh. We provide a helper <a href="https://github.com/rust-lang/josh-sync"><code>rustc-josh-sync</code></a> tool to help with the synchronization, described <a href="#synchronizing-a-josh-subtree">below</a>.</p> |
| <h3 id="synchronizing-a-josh-subtree"><a class="header" href="#synchronizing-a-josh-subtree">Synchronizing a Josh subtree</a></h3> |
| <p>We use a dedicated tool called <a href="https://github.com/rust-lang/josh-sync"><code>rustc-josh-sync</code></a> for performing Josh subtree updates. |
| The commands below can be used for all our Josh subtrees, although note that <code>miri</code> |
| requires you to perform some <a href="https://github.com/rust-lang/miri/blob/master/CONTRIBUTING.md#advanced-topic-syncing-with-the-rustc-repo">additional steps</a> during pulls.</p> |
| <p>You can install the tool using the following command:</p> |
| <pre><code>cargo install --locked --git https://github.com/rust-lang/josh-sync |
| </code></pre> |
| <p>Both pulls (synchronize changes from rust-lang/rust into the subtree) and pushes (synchronize |
| changes from the subtree to rust-lang/rust) are performed from the subtree repository (so first |
| switch to its repository checkout directory in your terminal).</p> |
| <h4 id="performing-pull"><a class="header" href="#performing-pull">Performing pull</a></h4> |
| <ol> |
| <li>Checkout a new branch that will be used to create a PR into the subtree</li> |
| <li>Run the pull command |
| <pre><code>rustc-josh-sync pull |
| </code></pre> |
| </li> |
| <li>Push the branch to your fork and create a PR into the subtree repository |
| <ul> |
| <li>If you have <code>gh</code> CLI installed, <code>rustc-josh-sync</code> can create the PR for you.</li> |
| </ul> |
| </li> |
| </ol> |
| <h4 id="performing-push"><a class="header" href="#performing-push">Performing push</a></h4> |
| <blockquote> |
| <p>NOTE: |
| Before you proceed, look at some guidance related to Git <a href="https://github.com/rust-lang/josh-sync#git-peculiarities">on josh-sync README</a>.</p> |
| </blockquote> |
| <ol> |
| <li>Run the push command to create a branch named <code><branch-name></code> in a <code>rustc</code> fork under the <code><gh-username></code> account |
| <pre><code>rustc-josh-sync push <branch-name> <gh-username> |
| </code></pre> |
| </li> |
| <li>Create a PR from <code><branch-name></code> into <code>rust-lang/rust</code></li> |
| </ol> |
| <h3 id="creating-a-new-josh-subtree-dependency"><a class="header" href="#creating-a-new-josh-subtree-dependency">Creating a new Josh subtree dependency</a></h3> |
| <p>If you want to migrate a repository dependency from <code>git subtree</code> or <code>git submodule</code> to josh, you can check out <a href="https://hackmd.io/7pOuxnkdQDaL1Y1FQr65xg">this guide</a>.</p> |
| <h3 id="synchronizing-a-git-subtree"><a class="header" href="#synchronizing-a-git-subtree">Synchronizing a git subtree</a></h3> |
| <p>Periodically the changes made to subtree based dependencies need to be synchronized between this |
| repository and the upstream tool repositories.</p> |
| <p>Subtree synchronizations are typically handled by the respective tool maintainers. Other users |
| are welcome to submit synchronization PRs, however, in order to do so you will need to modify |
| your local git installation and follow a very precise set of instructions. |
| These instructions are documented, along with several useful tips and tricks, in the |
| <a href="https://doc.rust-lang.org/nightly/clippy/development/infrastructure/sync.html">syncing subtree changes</a> section in Clippy's Contributing guide. |
| The instructions are applicable for use with any subtree based tool, just be sure to |
| use the correct corresponding subtree directory and remote repository.</p> |
| <p>The synchronization process goes in two directions: <code>subtree push</code> and <code>subtree pull</code>.</p> |
| <p>A <code>subtree push</code> takes all the changes that happened to the copy in this repo and creates commits |
| on the remote repo that match the local changes. Every local |
| commit that touched the subtree causes a commit on the remote repo, but |
| is modified to move the files from the specified directory to the tool repo root.</p> |
| <p>A <code>subtree pull</code> takes all changes since the last <code>subtree pull</code> |
| from the tool repo and adds these commits to the rustc repo along with a merge commit that moves |
| the tool changes into the specified directory in the Rust repository.</p> |
| <p>It is recommended that you always do a push first and get that merged to the default branch of the tool. |
| Then, when you do a pull, the merge works without conflicts. |
| While it's definitely possible to resolve conflicts during a pull, you may have to redo the conflict |
| resolution if your PR doesn't get merged fast enough and there are new conflicts. Do not try to |
| rebase the result of a <code>git subtree pull</code>, rebasing merge commits is a bad idea in general.</p> |
| <p>You always need to specify the <code>-P</code> prefix to the subtree directory and the corresponding remote |
| repository. If you specify the wrong directory or repository |
| you'll get very fun merges that try to push the wrong directory to the wrong remote repository. |
| Luckily you can just abort this without any consequences by throwing away either the pulled commits |
| in rustc or the pushed branch on the remote and try again. It is usually fairly obvious |
| that this is happening because you suddenly get thousands of commits that want to be synchronized.</p> |
| <h3 id="creating-a-new-subtree-dependency"><a class="header" href="#creating-a-new-subtree-dependency">Creating a new subtree dependency</a></h3> |
| <p>If you want to create a new subtree dependency from an existing repository, call (from this |
| repository's root directory!)</p> |
| <pre><code>git subtree add -P src/tools/clippy https://github.com/rust-lang/rust-clippy.git master |
| </code></pre> |
| <p>This will create a new commit, which you may not rebase under any circumstances! Delete the commit |
| and redo the operation if you need to rebase.</p> |
| <p>Now you're done, the <code>src/tools/clippy</code> directory behaves as if Clippy were |
| part of the rustc monorepo, so no one but you (or others that synchronize |
| subtrees) actually needs to use <code>git subtree</code>.</p> |
| <h2 id="external-dependencies-submodules"><a class="header" href="#external-dependencies-submodules">External Dependencies (submodules)</a></h2> |
| <p>Building Rust will also use external git repositories tracked using <a href="https://git-scm.com/book/en/v2/Git-Tools-Submodules">git |
| submodules</a>. The complete list may be found in the <a href="https://github.com/rust-lang/rust/blob/HEAD/.gitmodules"><code>.gitmodules</code></a> file. Some |
| of these projects are required (like <code>stdarch</code> for the standard library) and |
| some of them are optional (like <code>src/doc/book</code>).</p> |
| <p>Usage of submodules is discussed more in the <a href="git.html#git-submodules">Using Git chapter</a>.</p> |
| <p>Some of the submodules are allowed to be in a "broken" state where they |
| either don't build or their tests don't pass, e.g. the documentation books |
| like <a href="https://github.com/rust-lang/reference/">The Rust Reference</a>. Maintainers of these projects will be notified |
| when the project is in a broken state, and they should fix them as soon |
| as possible. The current status is tracked on the <a href="https://rust-lang-nursery.github.io/rust-toolstate/">toolstate website</a>. |
| More information may be found on the Forge <a href="https://forge.rust-lang.org/infra/toolstate.html">Toolstate chapter</a>. |
| In practice, it is very rare for documentation to have broken toolstate.</p> |
| <p>Breakage is not allowed in the beta and stable channels, and must be addressed |
| before the PR is merged. They are also not allowed to be broken on <code>main</code> in |
| the week leading up to the beta cut.</p> |
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