Roll stable and nightly toolchains separately (#446)

This should allow the stable toolchain to roll successfully sooner after
it's released. Previously, both toolchains were rolled together, which
meant that when the nightly roll failed (frequent thanks to most
nightlies missing at least one target architecture we use in CI), the
stable roll would fail too.

Author: joshlf

.github/workflows/roll-pinned-toolchain-versions.yml

@@ -17,8 +17,11 @@ permissions: read-all
 
 jobs:
   roll:
-    name: Roll pinned toolchain versions
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        toolchain: ["stable", "nightly"]
+    name: Roll pinned toolchain ${{ matrix.toolchain }} version
     steps:
       - name: Checkout code
         uses: actions/checkout@8ade135a41bc03ea155e62e844d188df1ea18608 # v4.1.0
@@ -30,17 +33,20 @@ jobs:
         # date has actually been published yet. This allows us to not worry
         # about what time of day this job runs.
         run: echo "ZC_TARGET_NIGHTLY=nightly-$(date -d '-1 day' +%Y-%m-%d)" >> $GITHUB_ENV
+        if: matrix.toolchain == 'nightly'
       - name: Install Rust with ${{ env.ZC_TARGET_NIGHTLY }} toolchain
         uses: dtolnay/rust-toolchain@00b49be78f40fba4e87296b2ead62868750bdd83 # stable
         with:
             toolchain: ${{ env.ZC_TARGET_NIGHTLY }}
+        if: matrix.toolchain == 'nightly'
         # Install whatever the latest stable release is. This has the side
         # effect of determining the latest stable release so that we can update
         # `Cargo.toml`.
       - name: Install Rust with stable toolchain
         uses: dtolnay/rust-toolchain@00b49be78f40fba4e87296b2ead62868750bdd83 # stable
         with:
             toolchain: stable
+        if: matrix.toolchain == 'stable'
       - name: Update files
         run: |
           set -eo pipefail
@@ -74,20 +80,24 @@ jobs:
             TRYBUILD=overwrite cargo "+$VERSION_FOR_CARGO" test --package zerocopy-derive
           }
 
-          STABLE_VERSION="$(cargo +stable version | sed -e 's/^cargo \([0-9\.]*\) .*/\1/')"
-          update-pinned-version stable  "$STABLE_VERSION"    stable               '--features __internal_use_only_features_that_work_on_stable'
-          update-pinned-version nightly "$ZC_TARGET_NIGHTLY" "$ZC_TARGET_NIGHTLY"  --all-features
+          if [ "${{ matrix.toolchain }}" == stable ]; then
+            STABLE_VERSION="$(cargo +stable version | sed -e 's/^cargo \([0-9\.]*\) .*/\1/')"
+            update-pinned-version stable "$STABLE_VERSION" stable '--features __internal_use_only_features_that_work_on_stable'
 
-          # Used as part of the branch name created by the "Submit PR" step.
-          echo "ZC_TARGET_STABLE=$STABLE_VERSION" >> $GITHUB_ENV
+            # Used as part of the branch name created by the "Submit PR" step.
+            echo "ZC_VERSION_FOR_BRANCH_NAME=$STABLE_VERSION" >> $GITHUB_ENV
+          else
+            update-pinned-version nightly "$ZC_TARGET_NIGHTLY" "$ZC_TARGET_NIGHTLY" --all-features
+            echo "ZC_VERSION_FOR_BRANCH_NAME=$ZC_TARGET_NIGHTLY" >> $GITHUB_ENV
+          fi
 
       - name: Submit PR
         uses: peter-evans/create-pull-request@153407881ec5c347639a548ade7d8ad1d6740e38 # v5.0.2
         with:
-          commit-message: "[ci] Roll pinned toolchains"
+          commit-message: "[ci] Roll pinned ${{ matrix.toolchain }} toolchain"
           author: Google PR Creation Bot <github-pull-request-creation-bot@google.com>
           committer: Google PR Creation Bot <github-pull-request-creation-bot@google.com>
-          title: "[ci] Roll pinned toolchains"
-          branch: roll-pinned-toolchain-to-${{ env.ZC_TARGET_STABLE }}-and-${{ env.ZC_TARGET_NIGHTLY }}
+          title: "[ci] Roll pinned ${{ matrix.toolchain }} toolchain"
+          branch: roll-pinned-${{ matrix.toolchain }}-toolchain-to-${{ env.ZC_VERSION_FOR_BRANCH_NAME }}
           push-to-fork: google-pr-creation-bot/zerocopy
           token: ${{ secrets.GOOGLE_PR_CREATION_BOT_TOKEN }}