luhenry · Oct 14, 2026
diff --git a/.github/workflows/build-zccache.yml b/.github/workflows/build-zccache.yml
@@ -0,0 +1,250 @@
+# SPDX-FileCopyrightText: 2026 The RISE Project
+# SPDX-License-Identifier: MIT
+---
+# This workflow is based on the `build`, `build-wheels` and `test-wheels` jobs of
+# https://github.com/zackees/zccache/blob/1.13.21/.github/workflows/release-auto.yml
+# (with its .github/actions/build-target/action.yml) and the `native-pytest` job of
+# https://github.com/zackees/zccache/blob/1.13.21/.github/workflows/python-tests.yml
+name: Build zccache wheels (riscv64)
+
+on:
+  workflow_dispatch:
+    inputs:
+      version:
+        description: 'Version glob to (re)build; empty builds every version of docs/packages/zccache.yaml not released yet'
+        required: false
+        default: ''
+  pull_request:
+    branches: [main]
+    paths:
+      - '.github/workflows/build-zccache.yml'
+      - 'docs/packages/zccache.yaml'
+      - 'patches/zccache/**'
+  push:
+    branches: [main]
+    paths:
+      - '.github/workflows/build-zccache.yml'
+      - 'docs/packages/zccache.yaml'
+      - 'patches/zccache/**'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read  # to fetch code (actions/checkout)
+
+env:
+  MANYLINUX_RISCV64_IMAGE: quay.io/pypa/manylinux_2_39_riscv64
+
+jobs:
+  setup:
+    uses: $/.github/workflows/_setup.yml
+    with:
+      package: zccache
+      version: ${{ inputs.version }}
+
+  build_wheel:
+    needs: [setup]
+    if: needs.setup.outputs.versions != '[]'
+    strategy:
+      fail-fast: false
+      matrix:
+        version: ${{ fromJSON(needs.setup.outputs.versions) }}
+    name: Build zccache ${{ matrix.version }} py3-none-manylinux_riscv64
+    runs-on: ubuntu-24.04-riscv
+    timeout-minutes: 1440
+
+    env:
+      ZCCACHE_VERSION: ${{ matrix.version }}
+
+    steps:
+      - name: Checkout zccache ${{ env.ZCCACHE_VERSION }}
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v7.0.1
+        with:
+          repository: zackees/zccache
+          ref: ${{ env.ZCCACHE_VERSION }}
+          persist-credentials: false
+
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v7.0.1
+        with:
+          path: python-wheels
+          persist-credentials: false
+
+      - name: Apply patches
+        run: git apply --verbose python-wheels/patches/zccache/${{ env.ZCCACHE_VERSION }}/*.patch
+
+      - name: Write container script
+        run: |
+          cat > riscv64-build.sh <<'EOF'
+          #!/bin/bash
+          set -e -x
+
+          export PATH="/opt/python/cp312-cp312/bin:${PATH}"
+          TARGET=riscv64gc-unknown-linux-gnu
+
+          # Upstream cross-compiles every target from x86_64 through soldr/zig; this builds natively instead.
+          curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --profile minimal --default-toolchain none
+          . "${HOME}/.cargo/env"
+          rustup toolchain install
+
+          dnf install -y protobuf-compiler
+
+          export PYO3_PYTHON=python
+          cargo build --release --target "${TARGET}" -p zccache \
+            --features zccache-bin,fingerprint-bin \
+            --bin zccache --bin zccache-fp
+          cargo build --release --target "${TARGET}" -p zccache-cli --features python --lib
+          cargo build --release --target "${TARGET}" -p zccache-watcher-py --lib
+          cargo build --release --target "${TARGET}" -p zccache-fingerprint-py --lib
+
+          release="target/${TARGET}/release"
+          staging=dist/linux-riscv64-gnu
+          mkdir -p "${staging}/python/zccache/fingerprint" "${staging}/python/zccache/watcher"
+          cp "${release}/zccache" "${release}/zccache-fp" "${staging}/"
+          cp "${release}/libzccache_cli.so" "${staging}/python/zccache/_native.so"
+          cp "${release}/libzccache_fingerprint.so" "${staging}/python/zccache/fingerprint/_native.so"
+          cp "${release}/libzccache_watcher.so" "${staging}/python/zccache/watcher/_native.so"
+          for f in "${staging}/zccache" "${staging}/zccache-fp" "${staging}"/python/zccache/{,fingerprint/,watcher/}_native.so; do
+            strip --strip-debug "${f}"
+          done
+
+          now="$(date -u +%s)"
+          for bin in zccache zccache-fp; do
+            python ci/stamp_release.py \
+              --binary "${staging}/${bin}" \
+              --sha "${ZCCACHE_SHA}" \
+              --version "${ZCCACHE_VERSION}" \
+              --triple "${TARGET}" \
+              --timestamp "${now}"
+          done
+
+          for bin in zccache zccache-fp; do
+            "${staging}/${bin}" --version | grep -Eq "^${bin} [0-9]"
+          done
+          export ZCCACHE_CACHE_DIR="$(mktemp -d)/cache"
+          "${staging}/zccache" "$(rustup which rustc)" -vV | grep -q '^host: '
+          "${staging}/zccache" start
+          "${staging}/zccache" status
+          "${staging}/zccache" stop
+
+          python - <<'PY'
+          from ci.release_workflow import build_wheel, read_project_meta
+
+          build_wheel(*read_project_meta(), "linux-riscv64-gnu", ["manylinux_2_39_riscv64"])
+          PY
+          EOF
+
+      - name: Build wheel
+        run: |
+          podman run -t \
+            --log-driver=none \
+            --network=host \
+            -v "${PWD}":/zccache_src \
+            --workdir /zccache_src \
+            -e ZCCACHE_VERSION="${ZCCACHE_VERSION}" \
+            -e ZCCACHE_SHA="$(git rev-parse HEAD)" \
+            --pull=newer \
+            "${MANYLINUX_RISCV64_IMAGE}" \
+            bash /zccache_src/riscv64-build.sh
+
+      - uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a  # v7.0.1
+        with:
+          name: zccache-${{ env.ZCCACHE_VERSION }}-py3-none-manylinux_riscv64
+          path: dist/wheels/*.whl
+          if-no-files-found: error
+
+  test_wheel:
+    name: Test zccache ${{ matrix.version }} ${{ matrix.python }}
+    needs: [setup, build_wheel]
+    if: needs.setup.outputs.versions != '[]'
+    runs-on: ubuntu-24.04-riscv
+    timeout-minutes: 120
+    strategy:
+      fail-fast: false
+      matrix:
+        version: ${{ fromJSON(needs.setup.outputs.versions) }}
+        # The pyo3 extensions are abi3, which free-threaded interpreters cannot load.
+        python: ["cp312", "cp313", "cp314"]
+
+    env:
+      ZCCACHE_VERSION: ${{ matrix.version }}
+
+    steps:
+      - name: Checkout zccache ${{ env.ZCCACHE_VERSION }}
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v7.0.1
+        with:
+          repository: zackees/zccache
+          ref: ${{ env.ZCCACHE_VERSION }}
+          persist-credentials: false
+
+      - uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c  # v8.0.1
+        with:
+          name: zccache-${{ env.ZCCACHE_VERSION }}-py3-none-manylinux_riscv64
+          path: dist/wheels
+
+      - name: Write container script
+        run: |
+          cat > riscv64-test.sh <<'EOF'
+          #!/bin/bash
+          set -e -x
+
+          export PATH="/opt/python/${PYTHON_TAG}-${PYTHON_TAG}/bin:${PATH}"
+
+          python -m pip install --only-binary=:all: /zccache_src/dist/wheels/*.whl pytest
+
+          zccache --version
+          zccache-fp --version
+          python -c 'import zccache._native, zccache.fingerprint._native, zccache.watcher._native'
+          python - <<'PY'
+          import importlib.metadata as md
+
+          shipped = {p.name for p in md.files("zccache") if ".dist-info/" in str(p)}
+          assert "LICENSE" in shipped, sorted(shipped)
+          PY
+
+          python ci/test_exec_cached_wheel.py
+
+          export ZCCACHE_CACHE_DIR="$(mktemp -d)/cache"
+          export ZCCACHE_DAEMON_NAMESPACE=native-python-tests
+          zccache start
+          for attempt in $(seq 1 30); do
+            zccache status && break
+            sleep 1
+          done
+          zccache status
+          python -m pytest python/tests -q -rs --durations=10
+          python -m pytest crates/zccache-watcher/python/tests -q -rs --durations=10
+          python -m pytest crates/zccache-fingerprint/python/tests -q -rs --durations=10
+          zccache stop
+          EOF
+
+      - name: Test wheel
+        run: |
+          podman run -t \
+            --log-driver=none \
+            --network=host \
+            -v "${PWD}":/zccache_src \
+            --workdir /zccache_src \
+            -e PYTHON_TAG="${{ matrix.python }}" \
+            -e PIP_EXTRA_INDEX_URL=https://pypi.riseproject.dev/simple/ \
+            --pull=newer \
+            "${MANYLINUX_RISCV64_IMAGE}" \
+            bash /zccache_src/riscv64-test.sh
+
+  publish:
+    name: Publish zccache ${{ matrix.version }}
+    needs: [setup, build_wheel, test_wheel]
+    if: needs.setup.outputs.versions != '[]'
+    strategy:
+      fail-fast: false
+      matrix:
+        version: ${{ fromJSON(needs.setup.outputs.versions) }}
+    permissions:
+      contents: write
+      pull-requests: write
+    uses: $/.github/workflows/_publish-wheel.yml
+    secrets:
+      app-private-key: ${{ secrets.RISEPROJECT_APP_PRIVATE_KEY }}
+    with:
+      artifact-pattern: zccache-${{ matrix.version }}-*-manylinux_riscv64
diff --git a/docs/packages/zccache.yaml b/docs/packages/zccache.yaml
@@ -0,0 +1,6 @@
+package-name: zccache
+source-code: https://github.com/zackees/zccache
+license: AGPL-3.0-only
+versions:
+- version: 1.13.21
+  patched: true
diff --git a/patches/zccache/1.13.21/0001-protocol-fall-back-to-prost-build-s-own-protoc-looku.patch b/patches/zccache/1.13.21/0001-protocol-fall-back-to-prost-build-s-own-protoc-looku.patch
@@ -0,0 +1,43 @@
+From 813a874854534eb6bbb9be60184312215ccf66bd Mon Sep 17 00:00:00 2001
+From: Ludovic Henry <git@ludovic.dev>
+Date: Wed, 14 Oct 2026 14:27:20 +0000
+Subject: [PATCH] protocol: fall back to prost-build's own protoc lookup on
+ riscv64
+
+Upstream-Status: Inappropriate [protoc-bin-vendored ships no riscv64 binary; prost_build already defaults to its own PROTOC-env/PATH lookup, so not overriding it on unsupported platforms is the whole fix]
+
+protoc_bin_vendored::protoc_bin_path() returns Err on any host outside
+its small set of prebuilt targets (x86, x86_64, aarch64, ppc64le, s390x,
+macOS, Windows), and build.rs turned that into a panic before
+prost_build ever got a chance to look for a protoc on PATH or via
+$PROTOC. Only exporting PROTOC when the vendored lookup succeeds
+restores that fallback, which prost-build documents in its "Sourcing
+protoc" section.
+
+Signed-off-by: Ludovic Henry <git@ludovic.dev>
+---
+ crates/zccache-protocol/build.rs | 8 +++++---
+ 1 file changed, 5 insertions(+), 3 deletions(-)
+
+diff --git a/crates/zccache-protocol/build.rs b/crates/zccache-protocol/build.rs
+index 7179f40..aba99f4 100644
+--- a/crates/zccache-protocol/build.rs
++++ b/crates/zccache-protocol/build.rs
+@@ -7,9 +7,11 @@ fn main() {
+     println!("cargo:rerun-if-changed=build.rs");
+     println!("cargo:rerun-if-changed=proto/zccache_v1.proto");
+
+-    let protoc = protoc_bin_vendored::protoc_bin_path()
+-        .expect("vendored protoc is available for zccache wire protobufs");
+-    std::env::set_var("PROTOC", protoc);
++    // protoc-bin-vendored ships no riscv64 binary; falling through leaves
++    // prost_build's own PROTOC-env/PATH lookup in charge there.
++    if let Ok(protoc) = protoc_bin_vendored::protoc_bin_path() {
++        std::env::set_var("PROTOC", protoc);
++    }
+
+     prost_build::Config::new()
+         .compile_protos(&["proto/zccache_v1.proto"], &["proto"])
+-- 
+2.43.0
+