diff --git a/README.md b/README.md index 70ec256e68..22d8e2357c 100644 --- a/README.md +++ b/README.md @@ -16,3 +16,52 @@ This repository contains two main crates: The `std::simd` component now lives in the [`packed_simd_2`](https://github.com/rust-lang/packed_simd) crate. + +## Synchronizing josh subtree with rustc + +This repository is linked to `rust-lang/rust` as a [josh](https://josh-project.github.io/josh/intro.html) subtree. You can use the following commands to synchronize the subtree in both directions. + +You'll need to install `josh-proxy` locally via + +``` +cargo install josh-proxy --git https://github.com/josh-project/josh --tag r24.10.04 +``` +Older versions of `josh-proxy` may not round trip commits losslessly so it is important to install this exact version. + +### Pull changes from `rust-lang/rust` into this repository + +1) Checkout a new branch that will be used to create a PR into `rust-lang/stdarch` +2) Run the pull command + ``` + cargo run --manifest-path josh-sync/Cargo.toml rustc-pull + ``` +3) Push the branch to your fork and create a PR into `stdarch` + +### Push changes from this repository into `rust-lang/rust` + +NOTE: If you use Git protocol to push to your fork of `rust-lang/rust`, +ensure that you have this entry in your Git config, +else the 2 steps that follow would prompt for a username and password: + +``` +[url "git@github.com:"] +insteadOf = "https://github.com/" +``` + +1) Run the push command to create a branch named `` in a `rustc` fork under the `` account + ``` + cargo run --manifest-path josh-sync/Cargo.toml rustc-push + ``` +2) Create a PR from `` into `rust-lang/rust` + +#### Minimal git config + +For simplicity (ease of implementation purposes), the josh-sync script simply calls out to system git. This means that the git invocation may be influenced by global (or local) git configuration. + +You may observe "Nothing to pull" even if you *know* rustc-pull has something to pull if your global git config sets `fetch.prunetags = true` (and possibly other configurations may cause unexpected outcomes). + +To minimize the likelihood of this happening, you may wish to keep a separate *minimal* git config that *only* has `[user]` entries from global git config, then repoint system git to use the minimal git config instead. 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crate::sync::{GitSync, RustcPullError}; + +mod sync; + +#[derive(clap::Parser)] +enum Args { + /// Pull changes from the main `rustc` repository. + /// This creates new commits that should be then merged into `stdarch`. + RustcPull, + /// Push changes from `stdarch` to the given `branch` of a `rustc` fork under the given + /// GitHub `username`. + /// The pushed branch should then be merged into the `rustc` repository. + RustcPush { branch: String, github_username: String }, +} + +fn main() -> anyhow::Result<()> { + let args = Args::parse(); + let sync = GitSync::from_current_dir()?; + match args { + Args::RustcPull => { + if let Err(error) = sync.rustc_pull(None) { + match error { + RustcPullError::NothingToPull => { + eprintln!("Nothing to pull"); + std::process::exit(2); + } + RustcPullError::PullFailed(error) => { + eprintln!("Pull failure: {error:?}"); + std::process::exit(1); + } + } + } + } + Args::RustcPush { github_username, branch } => { + sync.rustc_push(github_username, branch)?; + } + } + Ok(()) +} diff --git a/josh-sync/src/sync.rs b/josh-sync/src/sync.rs new file mode 100644 index 0000000000..f868a7b48e --- /dev/null +++ b/josh-sync/src/sync.rs @@ -0,0 +1,275 @@ +use std::io::Write; +use std::ops::Not; +use std::path::PathBuf; +use std::time::Duration; +use std::{env, net, process}; + +use anyhow::{Context, anyhow, bail}; +use xshell::{Shell, cmd}; + +/// Used for rustc syncs. +const JOSH_FILTER: &str = ":/library/stdarch"; +const JOSH_PORT: u16 = 42042; +const UPSTREAM_REPO: &str = "rust-lang/rust"; + +pub enum RustcPullError { + /// No changes are available to be pulled. + NothingToPull, + /// A rustc-pull has failed, probably a git operation error has occurred. + PullFailed(anyhow::Error), +} + +impl From for RustcPullError +where + E: Into, +{ + fn from(error: E) -> Self { + Self::PullFailed(error.into()) + } +} + +pub struct GitSync { + dir: PathBuf, +} + +/// This code was adapted from the miri repository +/// (https://github.com/rust-lang/miri/blob/6a68a79f38064c3bc30617cca4bdbfb2c336b140/miri-script/src/commands.rs#L236). +impl GitSync { + pub fn from_current_dir() -> anyhow::Result { + Ok(Self { dir: std::env::current_dir()? }) + } + + pub fn rustc_pull(&self, commit: Option) -> Result<(), RustcPullError> { + let sh = Shell::new()?; + sh.change_dir(&self.dir); + let commit = commit.map(Ok).unwrap_or_else(|| { + let rust_repo_head = + cmd!(sh, "git ls-remote https://github.com/{UPSTREAM_REPO}/ HEAD").read()?; + rust_repo_head + .split_whitespace() + .next() + .map(|front| front.trim().to_owned()) + .ok_or_else(|| anyhow!("Could not obtain Rust repo HEAD from remote.")) + })?; + // Make sure the repo is clean. + if cmd!(sh, "git status --untracked-files=no --porcelain").read()?.is_empty().not() { + return Err(anyhow::anyhow!( + "working directory must be clean before performing rustc pull" + ) + .into()); + } + // Make sure josh is running. + let josh = Self::start_josh()?; + let josh_url = + format!("http://localhost:{JOSH_PORT}/{UPSTREAM_REPO}.git@{commit}{JOSH_FILTER}.git"); + + let previous_base_commit = sh.read_file("rust-version")?.trim().to_string(); + if previous_base_commit == commit { + return Err(RustcPullError::NothingToPull); + } + + // Update rust-version file. As a separate commit, since making it part of + // the merge has confused the heck out of josh in the past. + // We pass `--no-verify` to avoid running git hooks. + // We do this before the merge so that if there are merge conflicts, we have + // the right rust-version file while resolving them. + sh.write_file("rust-version", format!("{commit}\n"))?; + const PREPARING_COMMIT_MESSAGE: &str = "Preparing for merge from rustc"; + cmd!(sh, "git commit rust-version --no-verify -m {PREPARING_COMMIT_MESSAGE}") + .run() + .context("FAILED to commit rust-version file, something went wrong")?; + + // Fetch given rustc commit. + cmd!(sh, "git fetch {josh_url}") + .run() + .inspect_err(|_| { + // Try to un-do the previous `git commit`, to leave the repo in the state we found it. + cmd!(sh, "git reset --hard HEAD^") + .run() + .expect("FAILED to clean up again after failed `git fetch`, sorry for that"); + }) + .context("FAILED to fetch new commits, something went wrong (committing the rust-version file has been undone)")?; + + // This should not add any new root commits. So count those before and after merging. + let num_roots = || -> anyhow::Result { + Ok(cmd!(sh, "git rev-list HEAD --max-parents=0 --count") + .read() + .context("failed to determine the number of root commits")? + .parse::()?) + }; + let num_roots_before = num_roots()?; + + let sha = + cmd!(sh, "git rev-parse HEAD").output().context("FAILED to get current commit")?.stdout; + + // Merge the fetched commit. + const MERGE_COMMIT_MESSAGE: &str = "Merge from rustc"; + cmd!(sh, "git merge FETCH_HEAD --no-verify --no-ff -m {MERGE_COMMIT_MESSAGE}") + .run() + .context("FAILED to merge new commits, something went wrong")?; + + let current_sha = + cmd!(sh, "git rev-parse HEAD").output().context("FAILED to get current commit")?.stdout; + if current_sha == sha { + cmd!(sh, "git reset --hard HEAD^") + .run() + .expect("FAILED to clean up after creating the preparation commit"); + eprintln!( + "No merge was performed, no changes to pull were found. Rolled back the preparation commit." + ); + return Err(RustcPullError::NothingToPull); + } + + // Check that the number of roots did not increase. + if num_roots()? != num_roots_before { + return Err(anyhow::anyhow!( + "Josh created a new root commit. This is probably not the history you want." + ) + .into()); + } + + drop(josh); + Ok(()) + } + + pub fn rustc_push(&self, github_user: String, branch: String) -> anyhow::Result<()> { + let sh = Shell::new()?; + sh.change_dir(&self.dir); + let base = sh.read_file("rust-version")?.trim().to_owned(); + // Make sure the repo is clean. + if cmd!(sh, "git status --untracked-files=no --porcelain").read()?.is_empty().not() { + bail!("working directory must be clean before running `rustc-push`"); + } + // Make sure josh is running. + let josh = Self::start_josh()?; + let josh_url = + format!("http://localhost:{JOSH_PORT}/{github_user}/rust.git{JOSH_FILTER}.git"); + + // Find a repo we can do our preparation in. + if let Ok(rustc_git) = env::var("RUSTC_GIT") { + // If rustc_git is `Some`, we'll use an existing fork for the branch updates. + sh.change_dir(rustc_git); + } else { + // Otherwise, do this in the local repo. + println!( + "This will pull a copy of the rust-lang/rust history into this checkout, growing it by about 1GB." + ); + print!( + "To avoid that, abort now and set the `RUSTC_GIT` environment variable to an existing rustc checkout. Proceed? [y/N] " + ); + std::io::stdout().flush()?; + let mut answer = String::new(); + std::io::stdin().read_line(&mut answer)?; + if answer.trim().to_lowercase() != "y" { + std::process::exit(1); + } + }; + // Prepare the branch. Pushing works much better if we use as base exactly + // the commit that we pulled from last time, so we use the `rust-version` + // file to find out which commit that would be. + println!("Preparing {github_user}/rust (base: {base})..."); + if cmd!(sh, "git fetch https://github.com/{github_user}/rust {branch}") + .ignore_stderr() + .read() + .is_ok() + { + println!( + "The branch '{branch}' seems to already exist in 'https://github.com/{github_user}/rust'. Please delete it and try again." + ); + std::process::exit(1); + } + cmd!(sh, "git fetch https://github.com/{UPSTREAM_REPO} {base}").run()?; + cmd!(sh, "git push https://github.com/{github_user}/rust {base}:refs/heads/{branch}") + .ignore_stdout() + .ignore_stderr() // silence the "create GitHub PR" message + .run()?; + println!(); + + // Do the actual push. + sh.change_dir(&self.dir); + println!("Pushing changes..."); + cmd!(sh, "git push {josh_url} HEAD:{branch}").run()?; + println!(); + + // Do a round-trip check to make sure the push worked as expected. + cmd!(sh, "git fetch {josh_url} {branch}").ignore_stderr().read()?; + let head = cmd!(sh, "git rev-parse HEAD").read()?; + let fetch_head = cmd!(sh, "git rev-parse FETCH_HEAD").read()?; + if head != fetch_head { + bail!( + "Josh created a non-roundtrip push! Do NOT merge this into rustc!\n\ + Expected {head}, got {fetch_head}." + ); + } + println!( + "Confirmed that the push round-trips back to stdarch properly. Please create a rustc PR:" + ); + println!( + // Open PR with `subtree update` title to silence the `no-merges` triagebot check + " https://github.com/{UPSTREAM_REPO}/compare/{github_user}:{branch}?quick_pull=1&title=stdarch+subtree+update&body=r?+@ghost" + ); + + drop(josh); + Ok(()) + } + + fn start_josh() -> anyhow::Result { + // Determine cache directory. + let local_dir = { + let user_dirs = + directories::ProjectDirs::from("org", "rust-lang", "stdarch-josh").unwrap(); + user_dirs.cache_dir().to_owned() + }; + + // Start josh, silencing its output. + let mut cmd = process::Command::new("josh-proxy"); + cmd.arg("--local").arg(local_dir); + cmd.arg("--remote").arg("https://github.com"); + cmd.arg("--port").arg(JOSH_PORT.to_string()); + cmd.arg("--no-background"); + cmd.stdout(process::Stdio::null()); + cmd.stderr(process::Stdio::null()); + let josh = cmd.spawn().context("failed to start josh-proxy, make sure it is installed")?; + + // Create a wrapper that stops it on drop. + struct Josh(process::Child); + impl Drop for Josh { + fn drop(&mut self) { + #[cfg(unix)] + { + // Try to gracefully shut it down. + process::Command::new("kill") + .args(["-s", "INT", &self.0.id().to_string()]) + .output() + .expect("failed to SIGINT josh-proxy"); + // Sadly there is no "wait with timeout"... so we just give it some time to finish. + std::thread::sleep(Duration::from_millis(100)); + // Now hopefully it is gone. + if self.0.try_wait().expect("failed to wait for josh-proxy").is_some() { + return; + } + } + // If that didn't work (or we're not on Unix), kill it hard. + eprintln!( + "I have to kill josh-proxy the hard way, let's hope this does not break anything." + ); + self.0.kill().expect("failed to SIGKILL josh-proxy"); + } + } + + // Wait until the port is open. We try every 10ms until 1s passed. + for _ in 0..100 { + // This will generally fail immediately when the port is still closed. + let josh_ready = net::TcpStream::connect_timeout( + &net::SocketAddr::from(([127, 0, 0, 1], JOSH_PORT)), + Duration::from_millis(1), + ); + if josh_ready.is_ok() { + return Ok(Josh(josh)); + } + // Not ready yet. + std::thread::sleep(Duration::from_millis(10)); + } + bail!("Even after waiting for 1s, josh-proxy is still not available.") + } +} diff --git a/rust-version b/rust-version new file mode 100644 index 0000000000..e69de29bb2