rust-lang · RalfJung · Jul 19, 2025 · Jul 19, 2025 · Jul 21, 2025 · Jul 21, 2025
diff --git a/src/tools/miri/.github/workflows/ci.yml b/src/tools/miri/.github/workflows/ci.yml
@@ -45,11 +45,17 @@ jobs:
             os: macos-latest
           - host_target: i686-pc-windows-msvc
             os: windows-latest
+          - host_target: aarch64-pc-windows-msvc
+            os: windows-11-arm
     runs-on: ${{ matrix.os }}
     env:
       HOST_TARGET: ${{ matrix.host_target }}
     steps:
       - uses: actions/checkout@v4
+      - name: apt update
+        if: ${{ startsWith(matrix.os, 'ubuntu') }}
+        # The runners seem to have outdated apt repos sometimes
+        run: sudo apt update
       - name: install qemu
         if: ${{ matrix.qemu }}
         run: sudo apt install qemu-user qemu-user-binfmt
@@ -63,6 +69,12 @@ jobs:
           sudo apt update
           # Install needed packages
           sudo apt install $(echo "libatomic1: zlib1g-dev:" | sed 's/:/:${{ matrix.multiarch }}/g')
+      - name: Install rustup on Windows ARM
+        if: ${{ matrix.os == 'windows-11-arm' }}
+        run: |
+            curl -LOs https://static.rust-lang.org/rustup/dist/aarch64-pc-windows-msvc/rustup-init.exe
+            ./rustup-init.exe -y --no-modify-path
+            echo "$USERPROFILE/.cargo/bin" >> "$GITHUB_PATH"
       - uses: ./.github/workflows/setup
         with:
           toolchain_flags: "--host ${{ matrix.host_target }}"
@@ -147,35 +159,48 @@ jobs:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 256 # get a bit more of the history
-      - name: install josh-proxy
-        run: cargo +stable install josh-proxy --git https://github.com/josh-project/josh --tag r24.10.04
+      - name: install josh-sync
+        run: cargo +stable install --locked --git https://github.com/rust-lang/josh-sync
       - name: setup bot git name and email
         run: |
           git config --global user.name 'The Miri Cronjob Bot'
           git config --global user.email '[email protected]'
       - name: Install nightly toolchain
         run: rustup toolchain install nightly --profile minimal
-      - name: get changes from rustc
-        run: ./miri rustc-pull
       - name: Install rustup-toolchain-install-master
         run: cargo install -f rustup-toolchain-install-master
-      - name: format changes (if any)
+      - name: Push changes to a branch and create PR
         run: |
+          # Make it easier to see what happens.
+          set -x
+          # Temporarily disable early exit to examine the status code of rustc-josh-sync
+          set +e
+          rustc-josh-sync pull
+          exitcode=$?
+          set -e
+
+          # If there were no changes to pull, rustc-josh-sync returns status code 2.
+          # In that case, skip the rest of the job.
+          if [ $exitcode -eq 2 ]; then
+            echo "Nothing changed in rustc, skipping PR"
+            exit 0
+          elif [ $exitcode -ne 0 ]; then
+            # If return code was not 0 or 2, rustc-josh-sync actually failed
+            echo "error: rustc-josh-sync failed"
+            exit ${exitcode}
+          fi
+
+          # Format changes
           ./miri toolchain
           ./miri fmt --check || (./miri fmt && git commit -am "fmt")
-      - name: Push changes to a branch and create PR
-        run: |
-          # `git diff --exit-code` "succeeds" if the diff is empty.
-          if git diff --exit-code HEAD^; then echo "Nothing changed in rustc, skipping PR"; exit 0; fi
-          # The diff is non-empty, create a PR.
+
+          # Create a PR
           BRANCH="rustup-$(date -u +%Y-%m-%d)"
           git switch -c $BRANCH
           git push -u origin $BRANCH
           gh pr create -B master --title 'Automatic Rustup' --body 'Please close and re-open this PR to trigger CI, then enable auto-merge.'
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-          ZULIP_BOT_EMAIL: ${{ secrets.ZULIP_BOT_EMAIL }}
-          ZULIP_API_TOKEN: ${{ secrets.ZULIP_API_TOKEN }}
 
   cron-fail-notify:
     name: cronjob failure notification
@@ -198,7 +223,7 @@ jobs:
           It would appear that the [Miri cron job build]('"https://github.com/$GITHUB_REPOSITORY/actions/runs/$GITHUB_RUN_ID"') failed.
 
           This likely means that rustc changed the miri directory and
-          we now need to do a [`./miri rustc-pull`](https://github.com/rust-lang/miri/blob/master/CONTRIBUTING.md#importing-changes-from-the-rustc-repo).
+          we now need to do a [`rustc-josh-sync pull`](https://github.com/rust-lang/miri/blob/master/CONTRIBUTING.md#importing-changes-from-the-rustc-repo).
 
           Would you mind investigating this issue?
 

diff --git a/src/tools/miri/CONTRIBUTING.md b/src/tools/miri/CONTRIBUTING.md
@@ -297,25 +297,27 @@ You can also directly run Miri on a Rust source file:
 
 ## Advanced topic: Syncing with the rustc repo
 
-We use the [`josh` proxy](https://github.com/josh-project/josh) to transmit changes between the
+We use the [`josh-sync`](https://github.com/rust-lang/josh-sync) tool to transmit changes between the
 rustc and Miri repositories. You can install it as follows:
 
 ```sh
-cargo +stable install josh-proxy --git https://github.com/josh-project/josh --tag r24.10.04
+cargo install --locked --git https://github.com/rust-lang/josh-sync
 ```
 
-Josh will automatically be started and stopped by `./miri`.
+The commands below will automatically install and manage the [Josh](https://github.com/josh-project/josh) proxy that performs the actual work.
 
 ### Importing changes from the rustc repo
 
 *Note: this usually happens automatically, so these steps rarely have to be done by hand.*
 
 We assume we start on an up-to-date master branch in the Miri repo.
 
+1) First, create a branch for the pull, e.g. `git checkout -b rustup`
+2) Then run the following:
 ```sh
 # Fetch and merge rustc side of the history. Takes ca 5 min the first time.
 # This will also update the `rustc-version` file.
-./miri rustc-pull
+rustc-josh-sync pull
 # Update local toolchain and apply formatting.
 ./miri toolchain && ./miri fmt
 git commit -am "rustup"
@@ -328,12 +330,12 @@ needed.
 
 ### Exporting changes to the rustc repo
 
-We will use the josh proxy to push to your fork of rustc. Run the following in the Miri repo,
+We will use the `josh-sync` tool to push to your fork of rustc. Run the following in the Miri repo,
 assuming we are on an up-to-date master branch:
 
 ```sh
 # Push the Miri changes to your rustc fork (substitute your github handle for YOUR_NAME).
-./miri rustc-push YOUR_NAME miri
+rustc-josh-sync push miri YOUR_NAME
 ```
 
 This will create a new branch called `miri` in your fork, and the output should include a link that

diff --git a/src/tools/miri/cargo-miri/src/phases.rs b/src/tools/miri/cargo-miri/src/phases.rs
@@ -1,9 +1,9 @@
 //! Implements the various phases of `cargo miri run/test`.
 
 use std::env;
-use std::fs::{self, File};
+use std::fs::File;
 use std::io::BufReader;
-use std::path::{Path, PathBuf};
+use std::path::{self, Path, PathBuf};
 use std::process::Command;
 
 use rustc_version::VersionMeta;
@@ -222,12 +222,12 @@ pub fn phase_cargo_miri(mut args: impl Iterator<Item = String>) {
     // that to be the Miri driver, but acting as rustc, in host mode.
     //
     // In `main`, we need the value of `RUSTC` to distinguish RUSTC_WRAPPER invocations from rustdoc
-    // or TARGET_RUNNER invocations, so we canonicalize it here to make it exceedingly unlikely that
+    // or TARGET_RUNNER invocations, so we make it absolute to make it exceedingly unlikely that
     // there would be a collision with other invocations of cargo-miri (as rustdoc or as runner). We
     // explicitly do this even if RUSTC_STAGE is set, since for these builds we do *not* want the
     // bootstrap `rustc` thing in our way! Instead, we have MIRI_HOST_SYSROOT to use for host
     // builds.
-    cmd.env("RUSTC", fs::canonicalize(find_miri()).unwrap());
+    cmd.env("RUSTC", path::absolute(find_miri()).unwrap());
     // In case we get invoked as RUSTC without the wrapper, let's be a host rustc. This makes no
     // sense for cross-interpretation situations, but without the wrapper, this will use the host
     // sysroot, so asking it to behave like a target build makes even less sense.

diff --git a/src/tools/miri/ci/ci.sh b/src/tools/miri/ci/ci.sh
@@ -142,7 +142,6 @@ case $HOST_TARGET in
     # Host
     GC_STRESS=1 MIR_OPT=1 MANY_SEEDS=64 TEST_BENCH=1 CARGO_MIRI_ENV=1 run_tests
     # Extra tier 1
-    MANY_SEEDS=64 TEST_TARGET=i686-unknown-linux-gnu run_tests
     MANY_SEEDS=64 TEST_TARGET=x86_64-apple-darwin run_tests
     MANY_SEEDS=64 TEST_TARGET=x86_64-pc-windows-gnu run_tests
     ;;
@@ -161,8 +160,6 @@ case $HOST_TARGET in
   aarch64-unknown-linux-gnu)
     # Host
     GC_STRESS=1 MIR_OPT=1 MANY_SEEDS=64 TEST_BENCH=1 CARGO_MIRI_ENV=1 run_tests
-    # Extra tier 1 candidate
-    MANY_SEEDS=64 TEST_TARGET=aarch64-pc-windows-msvc run_tests
     # Extra tier 2
     MANY_SEEDS=16 TEST_TARGET=arm-unknown-linux-gnueabi run_tests # 32bit ARM
     MANY_SEEDS=16 TEST_TARGET=aarch64-pc-windows-gnullvm run_tests # gnullvm ABI
@@ -189,13 +186,20 @@ case $HOST_TARGET in
     ;;
   i686-pc-windows-msvc)
     # Host
-    # Without GC_STRESS as this is the slowest runner.
+    # Without GC_STRESS as this is a very slow runner.
     MIR_OPT=1 MANY_SEEDS=64 TEST_BENCH=1 run_tests
     # Extra tier 1
     # We really want to ensure a Linux target works on a Windows host,
     # and a 64bit target works on a 32bit host.
     TEST_TARGET=x86_64-unknown-linux-gnu run_tests
     ;;
+  aarch64-pc-windows-msvc)
+    # Host
+    # Without GC_STRESS as this is a very slow runner.
+    MIR_OPT=1 MANY_SEEDS=64 TEST_BENCH=1 CARGO_MIRI_ENV=1 run_tests
+    # Extra tier 1
+    MANY_SEEDS=64 TEST_TARGET=i686-unknown-linux-gnu run_tests
+    ;;
   *)
     echo "FATAL: unknown host target: $HOST_TARGET"
     exit 1

diff --git a/src/tools/miri/josh-sync.toml b/src/tools/miri/josh-sync.toml
@@ -0,0 +1,2 @@
+repo = "miri"
+filter = ":rev(75dd959a3a40eb5b4574f8d2e23aa6efbeb33573:prefix=src/tools/miri):/src/tools/miri"
diff --git a/src/tools/miri/miri-script/Cargo.lock b/src/tools/miri/miri-script/Cargo.lock
@@ -116,27 +116,6 @@ version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b05b61dc5112cbb17e4b6cd61790d9845d13888356391624cbe7e41efeac1e75"
 
-[[package]]
-name = "directories"
-version = "6.0.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "16f5094c54661b38d03bd7e50df373292118db60b585c08a411c6d840017fe7d"
-dependencies = [
- "dirs-sys",
-]
-
-[[package]]
-name = "dirs-sys"
-version = "0.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e01a3366d27ee9890022452ee61b2b63a67e6f13f58900b651ff5665f0bb1fab"
-dependencies = [
- "libc",
- "option-ext",
- "redox_users",
- "windows-sys 0.60.2",
-]
-
 [[package]]
 name = "dunce"
 version = "1.0.5"
@@ -165,17 +144,6 @@ version = "2.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "37909eebbb50d72f9059c3b6d82c0463f2ff062c9e95845c43a6c9c0355411be"
 
-[[package]]
-name = "getrandom"
-version = "0.2.16"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "335ff9f135e4384c8150d6f27c6daed433577f86b4750418338c01a1a2528592"
-dependencies = [
- "cfg-if",
- "libc",
- "wasi 0.11.1+wasi-snapshot-preview1",
-]
-
 [[package]]
 name = "getrandom"
 version = "0.3.3"
@@ -185,7 +153,7 @@ dependencies = [
  "cfg-if",
  "libc",
  "r-efi",
- "wasi 0.14.2+wasi-0.2.4",
+ "wasi",
 ]
 
 [[package]]
@@ -221,16 +189,6 @@ version = "0.2.174"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1171693293099992e19cddea4e8b849964e9846f4acee11b3948bcc337be8776"
 
-[[package]]
-name = "libredox"
-version = "0.1.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1580801010e535496706ba011c15f8532df6b42297d2e471fec38ceadd8c0638"
-dependencies = [
- "bitflags",
- "libc",
-]
-
 [[package]]
 name = "linux-raw-sys"
 version = "0.9.4"
@@ -249,7 +207,6 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "clap",
- "directories",
  "dunce",
  "itertools",
  "path_macro",
@@ -275,12 +232,6 @@ version = "1.70.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a4895175b425cb1f87721b59f0f286c2092bd4af812243672510e1ac53e2e0ad"
 
-[[package]]
-name = "option-ext"
-version = "0.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "04744f49eae99ab78e0d5c0b603ab218f515ea8cfe5a456d7629ad883a3b6e7d"
-
 [[package]]
 name = "path_macro"
 version = "1.0.0"
@@ -311,17 +262,6 @@ version = "5.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "69cdb34c158ceb288df11e18b4bd39de994f6657d83847bdffdbd7f346754b0f"
 
-[[package]]
-name = "redox_users"
-version = "0.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dd6f9d3d47bdd2ad6945c5015a226ec6155d0bcdfd8f7cd29f86b71f8de99d2b"
-dependencies = [
- "getrandom 0.2.16",
- "libredox",
- "thiserror",
-]
-
 [[package]]
 name = "rustc_version"
 version = "0.4.1"
@@ -427,32 +367,12 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e8a64e3985349f2441a1a9ef0b853f869006c3855f2cda6862a94d26ebb9d6a1"
 dependencies = [
  "fastrand",
- "getrandom 0.3.3",
+ "getrandom",
  "once_cell",
  "rustix",
  "windows-sys 0.59.0",
 ]
 
-[[package]]
-name = "thiserror"
-version = "2.0.12"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "567b8a2dae586314f7be2a752ec7474332959c6460e02bde30d702a66d488708"
-dependencies = [
- "thiserror-impl",
-]
-
-[[package]]
-name = "thiserror-impl"
-version = "2.0.12"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7f7cf42b4507d8ea322120659672cf1b9dbb93f8f2d4ecfd6e51350ff5b17a1d"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn",
-]
-
 [[package]]
 name = "unicode-ident"
 version = "1.0.18"
@@ -475,12 +395,6 @@ dependencies = [
  "winapi-util",
 ]
 
-[[package]]
-name = "wasi"
-version = "0.11.1+wasi-snapshot-preview1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ccf3ec651a847eb01de73ccad15eb7d99f80485de043efb2f370cd654f4ea44b"
-
 [[package]]
 name = "wasi"
 version = "0.14.2+wasi-0.2.4"

diff --git a/src/tools/miri/miri-script/Cargo.toml b/src/tools/miri/miri-script/Cargo.toml
@@ -22,7 +22,6 @@ anyhow = "1.0"
 xshell = "0.2.6"
 rustc_version = "0.4"
 dunce = "1.0.4"
-directories = "6"
 serde = "1"
 serde_json = "1"
 serde_derive = "1"
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		repo = "miri"
		filter = ":rev(75dd959a3a40eb5b4574f8d2e23aa6efbeb33573:prefix=src/tools/miri):/src/tools/miri"