Merge from rust-lang/rust

Author: lnicola

.github/workflows/rustc-pull.yml

@@ -3,8 +3,8 @@ name: rustc-pull
 on:
   workflow_dispatch:
   schedule:
-    # Run at 04:00 UTC every Monday
-    - cron: '0 4 * * 1'
+    # Run at 04:00 UTC every Monday and Thursday
+    - cron: '0 4 * * 1,4'
 
 jobs:
   pull:
@@ -34,15 +34,35 @@ jobs:
           git config --global user.name 'The rustc-dev-guide Cronjob Bot'
           git config --global user.email 'github-actions@github.com'
       - name: Perform rustc-pull
-        run: cargo run --manifest-path josh-sync/Cargo.toml -- rustc-pull
+        id: rustc-pull
+        # Turn off -e to disable early exit
+        shell: bash {0}
+        run: |
+          cargo run --manifest-path josh-sync/Cargo.toml -- rustc-pull
+          exitcode=$?
+
+          # If no pull was performed, we want to mark this job as successful,
+          # but we do not want to perform the follow-up steps.
+          if [ $exitcode -eq 0 ]; then
+            echo "pull_result=pull-finished" >> $GITHUB_OUTPUT
+          elif [ $exitcode -eq 2 ]; then
+            echo "pull_result=skipped" >> $GITHUB_OUTPUT
+            exitcode=0
+          fi
+
+          exit ${exitcode}
       - name: Push changes to a branch
+        if: ${{ steps.rustc-pull.outputs.pull_result == 'pull-finished' }}
         run: |
           # Update a sticky branch that is used only for rustc pulls
           BRANCH="rustc-pull"
           git switch -c $BRANCH
           git push -u origin $BRANCH --force
       - name: Create pull request
         id: update-pr
+        if: ${{ steps.rustc-pull.outputs.pull_result == 'pull-finished' }}
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: |
           # Check if an open pull request for an rustc pull update already exists
           # If it does, the previous push has just updated it
@@ -54,26 +74,35 @@ jobs:
             echo "pr_url=$PR_URL" >> $GITHUB_OUTPUT
           else
             PR_URL=`gh pr list --author github-actions[bot] --state open -q 'map(select(.title=="Rustc pull update")) | .[0].url' --json url,title`
+            echo "Updating pull request ${PR_URL}"
             echo "pr_url=$PR_URL" >> $GITHUB_OUTPUT
           fi
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
   send-zulip-message:
     needs: [pull]
     if: ${{ !cancelled() }}
     runs-on: ubuntu-latest
     steps:
+      - uses: actions/checkout@v4
       - name: Compute message
-        id: message
+        id: create-message
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         run: |
-          if [ "${{ needs.pull.result }}" == "failure" ];
-          then
+          if [ "${{ needs.pull.result }}" == "failure" ]; then
             WORKFLOW_URL="${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}"
             echo "message=Rustc pull sync failed. Check out the [workflow URL]($WORKFLOW_URL)." >> $GITHUB_OUTPUT
           else
-            echo "message=Rustc pull sync succeeded. Check out the [PR](${{ needs.pull.outputs.pr_url }})." >> $GITHUB_OUTPUT
+            CREATED_AT=`gh pr list --author github-actions[bot] --state open -q 'map(select(.title=="Rustc pull update")) | .[0].createdAt' --json createdAt,title`
+            PR_URL=`gh pr list --author github-actions[bot] --state open -q 'map(select(.title=="Rustc pull update")) | .[0].url' --json url,title`
+            week_ago=$(date +%F -d '7 days ago')
+
+            # If there is an open PR that is at least a week old, post a message about it
+            if [[ -n $DATE_GH && $DATE_GH < $week_ago ]]; then
+              echo "message=A PR with a Rustc pull has been opened for more a week. Check out the [PR](${PR_URL})." >> $GITHUB_OUTPUT
+            fi
           fi
       - name: Send a Zulip message about updated PR
+        if: ${{ steps.create-message.outputs.message != '' }}
         uses: zulip/github-actions-zulip/send-message@e4c8f27c732ba9bd98ac6be0583096dea82feea5
         with:
           api-key: ${{ secrets.ZULIP_API_TOKEN }}

examples/rustc-driver-interacting-with-the-ast.rs

@@ -75,7 +75,7 @@ impl rustc_driver::Callbacks for MyCallbacks {
             let item = hir_krate.item(id);
             // Use pattern-matching to find a specific node inside the main function.
             if let rustc_hir::ItemKind::Fn(_, _, body_id) = item.kind {
-                let expr = &tcx.hir().body(body_id).value;
+                let expr = &tcx.hir_body(body_id).value;
                 if let rustc_hir::ExprKind::Block(block, _) = expr.kind {
                     if let rustc_hir::StmtKind::Let(let_stmt) = block.stmts[0].kind {
                         if let Some(expr) = let_stmt.init {

josh-sync/src/main.rs

@@ -1,5 +1,5 @@
 use clap::Parser;
-use crate::sync::GitSync;
+use crate::sync::{GitSync, RustcPullError};
 
 mod sync;
 
@@ -22,7 +22,18 @@ fn main() -> anyhow::Result<()> {
     let sync = GitSync::from_current_dir()?;
     match args {
         Args::RustcPull => {
-            sync.rustc_pull(None)?;
+            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)?;

josh-sync/src/sync.rs

@@ -11,6 +11,19 @@ const JOSH_FILTER: &str = ":/src/doc/rustc-dev-guide";
 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<E> From<E> for RustcPullError where E: Into<anyhow::Error> {
+    fn from(error: E) -> Self {
+        Self::PullFailed(error.into())
+    }
+}
+
 pub struct GitSync {
     dir: PathBuf,
 }
@@ -24,7 +37,7 @@ impl GitSync {
         })
     }
 
-    pub fn rustc_pull(&self, commit: Option<String>) -> anyhow::Result<()> {
+    pub fn rustc_pull(&self, commit: Option<String>) -> Result<(), RustcPullError> {
         let sh = Shell::new()?;
         sh.change_dir(&self.dir);
         let commit = commit.map(Ok).unwrap_or_else(|| {
@@ -38,7 +51,7 @@ impl GitSync {
         })?;
         // 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 performing rustc pull");
+            return Err(anyhow::anyhow!("working directory must be clean before performing rustc pull").into());
         }
         // Make sure josh is running.
         let josh = Self::start_josh()?;
@@ -47,7 +60,7 @@ impl GitSync {
 
         let previous_base_commit = sh.read_file("rust-version")?.trim().to_string();
         if previous_base_commit == commit {
-            return Err(anyhow::anyhow!("No changes since last pull"));
+            return Err(RustcPullError::NothingToPull);
         }
 
         // Update rust-version file. As a separate commit, since making it part of
@@ -94,12 +107,13 @@ impl GitSync {
             cmd!(sh, "git reset --hard HEAD^")
                 .run()
                 .expect("FAILED to clean up after creating the preparation commit");
-            return Err(anyhow::anyhow!("No merge was performed, nothing to pull. Rolled back 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 {
-            bail!("Josh created a new root commit. This is probably not the history you want.");
+            return Err(anyhow::anyhow!("Josh created a new root commit. This is probably not the history you want.").into());
         }
 
         drop(josh);

rust-version

@@ -1 +1 @@
-66d6064f9eb888018775e08f84747ee6f39ba28e
+124cc92199ffa924f6b4c7cc819a85b65e0c3984

src/appendix/bibliography.md

@@ -82,7 +82,7 @@ Rust, as well as publications about Rust.
 * [Ownership is Theft: Experiences Building an Embedded OS in Rust - Amit Levy, et. al.](https://amitlevy.com/papers/tock-plos2015.pdf)
 * [You can't spell trust without Rust](https://faultlore.com/blah/papers/thesis.pdf). Aria Beingessner's master's thesis.
 * [Rust-Bio: a fast and safe bioinformatics library](https://rust-bio.github.io/). Johannes Köster
-* [Safe, Correct, and Fast Low-Level Networking](https://octarineparrot.com/assets/msci_paper.pdf). Robert Clipsham's master's thesis.
+* [Safe, Correct, and Fast Low-Level Networking](https://csperkins.org/research/thesis-msci-clipsham.pdf). Robert Clipsham's master's thesis.
 * [Formalizing Rust traits](https://open.library.ubc.ca/cIRcle/collections/ubctheses/24/items/1.0220521). Jonatan Milewski's master's thesis.
 * [Rust as a Language for High Performance GC Implementation](https://dl.acm.org/doi/pdf/10.1145/3241624.2926707)
 * [Simple Verification of Rust Programs via Functional Purification](https://github.com/Kha/electrolysis). Sebastian Ullrich's master's thesis.

src/building/bootstrapping/debugging-bootstrap.md

@@ -76,6 +76,14 @@ $ BOOTSTRAP_TRACING=CONFIG_HANDLING=TRACE ./x build library --stage 1
 
 [tracing-env-filter]: https://docs.rs/tracing-subscriber/0.3.19/tracing_subscriber/filter/struct.EnvFilter.html
 
+##### FIXME(#96176): specific tracing for `compiler()` vs `compiler_for()`
+
+The additional targets `COMPILER` and `COMPILER_FOR` are used to help trace what
+`builder.compiler()` and `builder.compiler_for()` does. They should be removed
+if [#96176][cleanup-compiler-for] is resolved.
+
+[cleanup-compiler-for]: https://github.com/rust-lang/rust/issues/96176
+
 ### Using `tracing` in bootstrap
 
 Both `tracing::*` macros and the `tracing::instrument` proc-macro attribute need to be gated behind `tracing` feature. Examples:
@@ -121,6 +129,14 @@ For `#[instrument]`, it's recommended to:
 - Explicitly pick an instrumentation name via `name = ".."` to distinguish between e.g. `run` of different steps.
 - Take care to not cause diverging behavior via tracing, e.g. building extra things only when tracing infra is enabled.
 
+### Profiling bootstrap
+
+You can use the `COMMAND` tracing target to trace execution of most commands spawned by bootstrap. If you also use the `BOOTSTRAP_PROFILE=1` environment variable, bootstrap will generate a Chrome JSON trace file, which can be visualized in Chrome's `chrome://tracing` page or on https://ui.perfetto.dev.
+
+```bash
+$ BOOTSTRAP_TRACING=COMMAND=trace BOOTSTRAP_PROFILE=1 ./x build library
+```
+
 ### rust-analyzer integration?
 
 Unfortunately, because bootstrap is a `rust-analyzer.linkedProjects`, you can't ask r-a to check/build bootstrap itself with `tracing` feature enabled to get relevant completions, due to lack of support as described in <https://github.com/rust-lang/rust-analyzer/issues/8521>.

src/building/suggested.md

@@ -135,24 +135,24 @@ and follow the same instructions as above.
 ### Emacs
 
 Emacs provides support for rust-analyzer with project-local configuration
-through [Eglot](https://www.gnu.org/software/emacs/manual/html_node/eglot/).  
+through [Eglot](https://www.gnu.org/software/emacs/manual/html_node/eglot/).
 Steps for setting up Eglot with rust-analyzer can be [found
-here](https://rust-analyzer.github.io/manual.html#eglot).  
+here](https://rust-analyzer.github.io/manual.html#eglot).
 Having set up Emacs & Eglot for Rust development in general, you can run
 `./x setup editor` and select `emacs`, which will prompt you to create
 `.dir-locals.el` with the recommended configuration for Eglot.
-The recommended settings live at [`src/etc/rust_analyzer_eglot.el`].  
+The recommended settings live at [`src/etc/rust_analyzer_eglot.el`].
 For more information on project-specific Eglot configuration, consult [the
 manual](https://www.gnu.org/software/emacs/manual/html_node/eglot/Project_002dspecific-configuration.html).
 
 ### Helix
 
-Helix comes with built-in LSP and rust-analyzer support.  
+Helix comes with built-in LSP and rust-analyzer support.
 It can be configured through `languages.toml`, as described
-[here](https://docs.helix-editor.com/languages.html).  
+[here](https://docs.helix-editor.com/languages.html).
 You can run `./x setup editor` and select `helix`, which will prompt you to
 create `languages.toml` with the recommended configuration for Helix. The
-recommended settings live at [`src/etc/rust_analyzer_helix.toml`].  
+recommended settings live at [`src/etc/rust_analyzer_helix.toml`].
 
 ## Check, check, and check again
 
@@ -181,7 +181,7 @@ example, running `tidy` and `linkchecker` is useful when editing Markdown files,
 whereas UI tests are much less likely to be helpful. While `x suggest` is a
 useful tool, it does not guarantee perfect coverage (just as PR CI isn't a
 substitute for bors). See the [dedicated chapter](../tests/suggest-tests.md) for
-more information and contribution instructions. 
+more information and contribution instructions.
 
 Please note that `x suggest` is in a beta state currently and the tests that it
 will suggest are limited.
@@ -332,29 +332,22 @@ git worktree add -b my-feature ../rust2 master
 You can then use that rust2 folder as a separate workspace for modifying and
 building `rustc`!
 
-## Using nix-shell
+## Working with nix
 
-If you're using nix, you can use the following nix-shell to work on Rust:
+Several nix configurations are defined in `src/tools/nix-dev-shell`.
 
-```nix
-{ pkgs ? import <nixpkgs> {} }:
-pkgs.mkShell {
-  name = "rustc";
-  nativeBuildInputs = with pkgs; [
-    binutils cmake ninja pkg-config python3 git curl cacert patchelf nix
-  ];
-  buildInputs = with pkgs; [
-    openssl glibc.out glibc.static
-  ];
-  # Avoid creating text files for ICEs.
-  RUSTC_ICE = "0";
-  # Provide `libstdc++.so.6` for the self-contained lld.
-  LD_LIBRARY_PATH = "${with pkgs; lib.makeLibraryPath [
-    stdenv.cc.cc.lib
-  ]}";
-}
+If you're using direnv, you can create a symbol link to `src/tools/nix-dev-shell/envrc-flake` or `src/tools/nix-dev-shell/envrc-shell`
+
+```bash
+ln -s ./src/tools/nix-dev-shell/envrc-flake ./.envrc # Use flake
+```
+or
+```bash
+ln -s ./src/tools/nix-dev-shell/envrc-shell ./.envrc # Use nix-shell
 ```
 
+### Note
+
 Note that when using nix on a not-NixOS distribution, it may be necessary to set
 **`patch-binaries-for-nix = true` in `config.toml`**. Bootstrap tries to detect
 whether it's running in nix and enable patching automatically, but this

src/diagnostics.md

@@ -601,8 +601,8 @@ The trait implementation allows you to check certain syntactic constructs
 as the linter walks the AST. You can then choose to emit lints in a
 very similar way to compile errors.
 
-You also declare the metadata of a particular lint via the `declare_lint!`
-macro. [This macro](https://doc.rust-lang.org/nightly/nightly-rustc/rustc_lint_defs/macro.declare_lint.html) includes the name, the default level, a short description, and some
+You also declare the metadata of a particular lint via the [`declare_lint!`]
+macro. This macro includes the name, the default level, a short description, and some
 more details.
 
 Note that the lint and the lint pass must be registered with the compiler.
@@ -671,6 +671,8 @@ example-use-loop = denote infinite loops with `loop {"{"} ... {"}"}`
   .suggestion = use `loop`
 ```
 
+[`declare_lint!`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_lint_defs/macro.declare_lint.html
+
 ### Edition-gated lints
 
 Sometimes we want to change the behavior of a lint in a new edition. To do this,

src/getting-started.md

@@ -101,7 +101,6 @@ it's easy to pick up work without a large time commitment:
 - [Rustdoc Askama Migration](https://github.com/rust-lang/rust/issues/108868)
 - [Diagnostic Translation](https://github.com/rust-lang/rust/issues/100717)
 - [Move UI tests to subdirectories](https://github.com/rust-lang/rust/issues/73494)
-- [Port run-make tests from Make to Rust](https://github.com/rust-lang/rust/issues/121876)
 
 If you find more recurring work, please feel free to add it here!
 

src/implementing_new_features.md

@@ -9,7 +9,11 @@ smoothly.
 **NOTE: this section is for *language* features, not *library* features,
 which use [a different process].**
 
+See also [the Rust Language Design Team's procedures][lang-propose] for
+proposing changes to the language.
+
 [a different process]: ./stability.md
+[lang-propose]: https://lang-team.rust-lang.org/how_to/propose.html
 
 ## The @rfcbot FCP process
 

src/mir/index.md

@@ -304,9 +304,9 @@ The most important rule for
 this representation is that every value must be uniquely represented. In other
 words: a specific value must only be representable in one specific way. For example: there is only
 one way to represent an array of two integers as a `ValTree`:
-`ValTree::Branch(&[ValTree::Leaf(first_int), ValTree::Leaf(second_int)])`.
+`Branch([Leaf(first_int), Leaf(second_int)])`.
 Even though theoretically a `[u32; 2]` could be encoded in a `u64` and thus just be a
-`ValTree::Leaf(bits_of_two_u32)`, that is not a legal construction of `ValTree`
+`Leaf(bits_of_two_u32)`, that is not a legal construction of `ValTree`
 (and is very complex to do, so it is unlikely anyone is tempted to do so).
 
 These rules also mean that some values are not representable. There can be no `union`s in type

src/parallel-rustc.md

@@ -46,8 +46,6 @@ are implemented differently depending on whether `parallel-compiler` is true.
 
 | data structure                   | parallel                                            | non-parallel |
 | -------------------------------- | --------------------------------------------------- | ------------ |
-| Weak                             | std::sync::Weak                                     | std::rc::Weak |
-| Atomic{Bool}/{Usize}/{U32}/{U64} | std::sync::atomic::Atomic{Bool}/{Usize}/{U32}/{U64} | (std::cell::Cell<bool/usize/u32/u64>) |
 | OnceCell                         | std::sync::OnceLock                                 | std::cell::OnceCell |
 | Lock\<T> | (parking_lot::Mutex\<T>) | (std::cell::RefCell) |
 | RwLock\<T> | (parking_lot::RwLock\<T>) | (std::cell::RefCell) |
@@ -58,7 +56,6 @@ are implemented differently depending on whether `parallel-compiler` is true.
 | WriteGuard | parking_lot::RwLockWriteGuard | std::cell::RefMut |
 | MappedWriteGuard | parking_lot::MappedRwLockWriteGuard | std::cell::RefMut |
 | LockGuard | parking_lot::MutexGuard | std::cell::RefMut |
-| MappedLockGuard | parking_lot::MappedMutexGuard | std::cell::RefMut |
 
 - These thread-safe data structures are interspersed during compilation which
   can cause lock contention resulting in degraded performance as the number of
@@ -173,12 +170,10 @@ Here are some resources that can be used to learn more:
 - [This list of interior mutability in the compiler by nikomatsakis][imlist]
 
 [`rayon`]: https://crates.io/crates/rayon
-[Arc]: https://doc.rust-lang.org/std/sync/struct.Arc.html
 [imlist]: https://github.com/nikomatsakis/rustc-parallelization/blob/master/interior-mutability-list.md
 [irlo0]: https://internals.rust-lang.org/t/parallelizing-rustc-using-rayon/6606
 [irlo1]: https://internals.rust-lang.org/t/help-test-parallel-rustc/11503
 [monomorphization]: backend/monomorph.md
 [parallel-rustdoc]: https://github.com/rust-lang/rust/issues/82741
-[Rc]: https://doc.rust-lang.org/std/rc/struct.Rc.html
 [rustc-rayon]: https://github.com/rust-lang/rustc-rayon
 [tracking]: https://github.com/rust-lang/rust/issues/48685