From 357b5f9ed868e96b42d5ddd2e6db319bdfff693a Mon Sep 17 00:00:00 2001
From: Sebastian Ullrich <sebasti@nullri.ch>
Date: Thu, 3 Jul 2025 22:55:14 +0200
Subject: [PATCH] chore: CI: restore cache in `update-stage0` (#9179)

Avoid rebuilding stage 0 all the time
---
 .github/workflows/build-template.yml |  4 ++--
 .github/workflows/update-stage0.yml  | 12 ++++++++++++
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/build-template.yml b/.github/workflows/build-template.yml
index 23145f971b..39e6760e64 100644
--- a/.github/workflows/build-template.yml
+++ b/.github/workflows/build-template.yml
@@ -97,11 +97,11 @@ jobs:
           sudo apt-get update
           sudo apt-get install -y gcc-multilib g++-multilib ccache libuv1-dev:i386 pkgconf:i386
         if: matrix.cmultilib
-      - name: Cache
+      - name: Restore Cache
         id: restore-cache
         uses: actions/cache/restore@v4
         with:
-          # NOTE: must be in sync with `save` below
+          # NOTE: must be in sync with `save` below and with `restore-cache` in `update-stage0.yml`
           path: |
             .ccache
             ${{ matrix.name == 'Linux Lake' && false && 'build/stage1/**/*.trace
diff --git a/.github/workflows/update-stage0.yml b/.github/workflows/update-stage0.yml
index 95473d085e..5d72debe66 100644
--- a/.github/workflows/update-stage0.yml
+++ b/.github/workflows/update-stage0.yml
@@ -52,6 +52,18 @@ jobs:
       run: |
         echo "NPROC=$(nproc 2>/dev/null || sysctl -n hw.logicalcpu 2>/dev/null || echo 4)" >> $GITHUB_ENV
       shell: 'nix develop -c bash -euxo pipefail {0}'
+    - name: Restore Cache
+      if: env.should_update_stage0 == 'yes'
+      uses: actions/cache/restore@v4
+      with:
+        # NOTE: must be in sync with `restore-cache` in `build-template.yml`
+        # TODO: actually switch to USE_LAKE once it caches more; for now it just caches more often than any other build type so let's use its cache
+        path: |
+          .ccache
+        key: Linux Lake-build-v3-${{ github.sha }}
+        # fall back to (latest) previous cache
+        restore-keys: |
+          Linux Lake-build-v3
     - if: env.should_update_stage0 == 'yes'
       run: cmake --preset release
       shell: 'nix develop -c bash -euxo pipefail {0}'