refactor: Replace 'on: pull_request: paths' by 'changed-files' action (#5728)

This PR moves the list of files from the `paths:` section in the `on: pull_request` into a separate job.

.github/scripts/strategy-matrix/generate.py

@@ -38,7 +38,7 @@ def generate_strategy_matrix(all: bool, architecture: list[dict], os: list[dict]
             # - Bookworm using GCC 13: Release and Unity on linux/arm64, set
             #   the reference fee to 500.
             # - Bookworm using GCC 15: Debug and no Unity on linux/amd64, enable
-            #   code coverage.
+            #   code coverage (which will be done below).
             # - Bookworm using Clang 16: Debug and no Unity on linux/arm64,
             #   enable voidstar.
             # - Bookworm using Clang 17: Release and no Unity on linux/amd64,
@@ -51,9 +51,6 @@ def generate_strategy_matrix(all: bool, architecture: list[dict], os: list[dict]
                         cmake_args = f'-DUNIT_TEST_REFERENCE_FEE=500 {cmake_args}'
                         skip = False
                     if f'{os['compiler_name']}-{os['compiler_version']}' == 'gcc-15' and build_type == 'Debug' and '-Dunity=OFF' in cmake_args and architecture['platform'] == 'linux/amd64':
-                        cmake_args = f'-Dcoverage=ON -Dcoverage_format=xml -DCODE_COVERAGE_VERBOSE=ON -DCMAKE_C_FLAGS=-O0 -DCMAKE_CXX_FLAGS=-O0 {cmake_args}'
-                        cmake_target = 'coverage'
-                        build_only = True
                         skip = False
                     if f'{os['compiler_name']}-{os['compiler_version']}' == 'clang-16' and build_type == 'Debug' and '-Dunity=OFF' in cmake_args and architecture['platform'] == 'linux/arm64':
                         cmake_args = f'-Dvoidstar=ON {cmake_args}'
@@ -127,6 +124,13 @@ def generate_strategy_matrix(all: bool, architecture: list[dict], os: list[dict]
         if f'{os['compiler_name']}-{os['compiler_version']}' == 'clang-20' and architecture['platform'] == 'linux/arm64':
             continue
 
+        # Enable code coverage for Debian Bookworm using GCC 15 in Debug and no
+        # Unity on linux/amd64
+        if f'{os['compiler_name']}-{os['compiler_version']}' == 'gcc-15' and build_type == 'Debug' and '-Dunity=OFF' in cmake_args and architecture['platform'] == 'linux/amd64':
+            cmake_args = f'-Dcoverage=ON -Dcoverage_format=xml -DCODE_COVERAGE_VERBOSE=ON -DCMAKE_C_FLAGS=-O0 -DCMAKE_CXX_FLAGS=-O0 {cmake_args}'
+            cmake_target = 'coverage'
+            build_only = True
+
         # Generate a unique name for the configuration, e.g. macos-arm64-debug
         # or debian-bookworm-gcc-12-amd64-release-unity.
         config_name = os['distro_name']

.github/workflows/on-pr.yml

@@ -6,29 +6,6 @@ name: PR
 
 on:
   pull_request:
-    paths:
-      - ".github/actions/build-deps/**"
-      - ".github/actions/build-test/**"
-      - ".github/scripts/levelization/**"
-      - ".github/scripts/strategy-matrix/**"
-      - ".github/workflows/build-test.yml"
-      - ".github/workflows/check-format.yml"
-      - ".github/workflows/check-levelization.yml"
-      - ".github/workflows/notify-clio.yml"
-      - ".github/workflows/on-pr.yml"
-      # Keep the list of paths below in sync with those in the `on-trigger.yml`
-      # file.
-      - "cmake/**"
-      - "conan/**"
-      - "external/**"
-      - "include/**"
-      - "src/**"
-      - "tests/**"
-      - ".clang-format"
-      - ".codecov.yml"
-      - ".pre-commit-config.yaml"
-      - "CMakeLists.txt"
-      - "conanfile.py"
     types:
       - opened
       - reopened
@@ -57,18 +34,66 @@ jobs:
       - name: No-op
         run: true
 
-  check-format:
+  # This job checks whether any files have changed that should cause the next
+  # jobs to run. We do it this way rather than using `paths` in the `on:`
+  # section, because all required checks must pass, even for changes that do not
+  # modify anything that affects those checks. We would therefore like to make
+  # the checks required only if the job runs, but GitHub does not support that
+  # directly. By always executing the workflow on new commits and by using the
+  # changed-files action below, we ensure that Github considers any skipped jobs
+  # to have passed, and in turn the required checks as well.
+  any-changed:
     needs: should-run
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@08eba0b27e820071cde6df949e0beb9ba4906955 # v4.3.0
+      - name: Determine changed files
+        id: changes
+        uses: tj-actions/changed-files@ed68ef82c095e0d48ec87eccea555d944a631a4c # v46.0.5
+        with:
+          files: |
+            # These paths are unique to `on-pr.yml`.
+            .github/scripts/levelization/**
+            .github/workflows/check-format.yml
+            .github/workflows/check-levelization.yml
+            .github/workflows/notify-clio.yml
+            .github/workflows/on-pr.yml
+            .clang-format
+            .pre-commit-config.yaml
+
+            # Keep the paths below in sync with those in `on-trigger.yml`.
+            .github/actions/build-deps/**
+            .github/actions/build-test/**
+            .github/scripts/strategy-matrix/**
+            .github/workflows/build-test.yml
+            .codecov.yml
+            cmake/**
+            conan/**
+            external/**
+            include/**
+            src/**
+            tests/**
+            CMakeLists.txt
+            conanfile.py
+    outputs:
+      changed: ${{ steps.changes.outputs.any_changed }}
+
+  check-format:
+    needs: any-changed
+    if: needs.any-changed.outputs.changed == 'true'
     uses: ./.github/workflows/check-format.yml
 
   check-levelization:
-    needs: should-run
+    needs: any-changed
+    if: needs.any-changed.outputs.changed == 'true'
     uses: ./.github/workflows/check-levelization.yml
 
   # This job works around the limitation that GitHub Actions does not support
   # using environment variables as inputs for reusable workflows.
   generate-outputs:
-    needs: should-run
+    needs: any-changed
+    if: needs.any-changed.outputs.changed == 'true'
     runs-on: ubuntu-latest
     steps:
       - name: No-op

.github/workflows/on-trigger.yml

@@ -13,31 +13,33 @@ on:
       - release
       - master
     paths:
+      # These paths are unique to `on-trigger.yml`.
+      - ".github/workflows/check-missing-commits.yml"
+      - ".github/workflows/on-trigger.yml"
+      - ".github/workflows/publish-docs.yml"
+
+      # Keep the paths below in sync with those in `on-pr.yml`.
       - ".github/actions/build-deps/**"
       - ".github/actions/build-test/**"
       - ".github/scripts/strategy-matrix/**"
       - ".github/workflows/build-test.yml"
-      - ".github/workflows/check-missing-commits.yml"
-      - ".github/workflows/on-trigger.yml"
-      - ".github/workflows/publish-docs.yml"
-      # Keep the list of paths below in sync with those in `on-pr.yml`.
+      - ".codecov.yml"
       - "cmake/**"
       - "conan/**"
       - "external/**"
       - "include/**"
       - "src/**"
       - "tests/**"
-      - ".clang-format"
-      - ".codecov.yml"
-      - ".pre-commit-config.yaml"
       - "CMakeLists.txt"
       - "conanfile.py"
+
   # Run at 06:32 UTC on every day of the week from Monday through Friday. This
   # will force all dependencies to be rebuilt, which is useful to verify that
   # all dependencies can be built successfully. Only the dependencies that
   # are actually missing from the remote will be uploaded.
   schedule:
     - cron: "32 6 * * 1-5"
+
   # Run when manually triggered via the GitHub UI or API. If `force_upload` is
   # true, then the dependencies that were missing (`force_rebuild` is false) or
   # rebuilt (`force_rebuild` is true) will be uploaded, overwriting existing