ci: run coverage jobs in pull_request_target context (#4483)

Author: davidhewitt

.github/workflows/ci.yml

@@ -385,46 +385,6 @@ jobs:
           components: rust-src
       - run: cargo rustdoc --lib --no-default-features --features full -Zunstable-options --config "build.rustdocflags=[\"--cfg\", \"docsrs\"]"
 
-  coverage:
-    needs: [fmt]
-    name: coverage ${{ matrix.os }}
-    strategy:
-      matrix:
-        os: ["windows-latest", "macos-14", "ubuntu-latest"]  # first available arm macos runner
-    runs-on: ${{ matrix.os }}
-    steps:
-      - if: ${{ github.event_name == 'pull_request' && matrix.os != 'ubuntu-latest' }}
-        id: should-skip
-        shell: bash
-        run: echo 'skip=true' >> $GITHUB_OUTPUT
-      - uses: actions/checkout@v4
-        if: steps.should-skip.outputs.skip != 'true'
-      - uses: actions/setup-python@v5
-        if: steps.should-skip.outputs.skip != 'true'
-        with:
-          python-version: '3.12'
-      - uses: Swatinem/rust-cache@v2
-        if: steps.should-skip.outputs.skip != 'true'
-        with:
-          save-if: ${{ github.event_name != 'merge_group' }}
-      - uses: dtolnay/rust-toolchain@stable
-        if: steps.should-skip.outputs.skip != 'true'
-        with:
-          components: llvm-tools-preview,rust-src
-      - name: Install cargo-llvm-cov
-        if: steps.should-skip.outputs.skip != 'true'
-        uses: taiki-e/install-action@cargo-llvm-cov
-      - run: python -m pip install --upgrade pip && pip install nox
-        if: steps.should-skip.outputs.skip != 'true'
-      - run: nox -s coverage
-        if: steps.should-skip.outputs.skip != 'true'
-      - uses: codecov/codecov-action@v4
-        if: steps.should-skip.outputs.skip != 'true'
-        with:
-          file: coverage.json
-          name: ${{ matrix.os }}
-          token: ${{ secrets.CODECOV_TOKEN }}
-
   emscripten:
     name: emscripten
     if: ${{ contains(github.event.pull_request.labels.*.name, 'CI-build-full') || github.event_name != 'pull_request' }}
@@ -673,7 +633,6 @@ jobs:
       - valgrind
       - careful
       - docsrs
-      - coverage
       - emscripten
       - test-debug
       - test-free-threaded

.github/workflows/coverage.yml

@@ -0,0 +1,54 @@
+name: Coverage
+
+on:
+  push:
+    branches:
+      - main
+  pull_request_target:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref_name }}-coverage
+  cancel-in-progress: true
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  coverage:
+    name: coverage ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: ["windows-latest", "macos-14", "ubuntu-latest"]  # first available arm macos runner
+    runs-on: ${{ matrix.os }}
+    steps:
+      - if: ${{ github.event_name == 'pull_request' && matrix.os != 'ubuntu-latest' }}
+        id: should-skip
+        shell: bash
+        run: echo 'skip=true' >> $GITHUB_OUTPUT
+      - uses: actions/checkout@v4
+        if: steps.should-skip.outputs.skip != 'true'
+      - uses: actions/setup-python@v5
+        if: steps.should-skip.outputs.skip != 'true'
+        with:
+          python-version: '3.12'
+      - uses: Swatinem/rust-cache@v2
+        if: steps.should-skip.outputs.skip != 'true'
+        with:
+          save-if: ${{ github.event_name != 'merge_group' }}
+      - uses: dtolnay/rust-toolchain@stable
+        if: steps.should-skip.outputs.skip != 'true'
+        with:
+          components: llvm-tools-preview,rust-src
+      - name: Install cargo-llvm-cov
+        if: steps.should-skip.outputs.skip != 'true'
+        uses: taiki-e/install-action@cargo-llvm-cov
+      - run: python -m pip install --upgrade pip && pip install nox
+        if: steps.should-skip.outputs.skip != 'true'
+      - run: nox -s coverage
+        if: steps.should-skip.outputs.skip != 'true'
+      - uses: codecov/codecov-action@v4
+        if: steps.should-skip.outputs.skip != 'true'
+        with:
+          file: coverage.json
+          name: ${{ matrix.os }}
+          token: ${{ secrets.CODECOV_TOKEN }}