CI: Speed up static checks by checking only changed files

- file_format, header_guards and clang-format benefit from this short list.
- dotnet-format, Python and JS checks don't, but they're only relevant for
  PRs changing a specific set of files, so we skip them when those files
  aren't modified.

The logic to get changed files only works reliably for:
- Pull request events
- Non-force pushed push events

So when force pushing a branch in your fork, or creating a new branch,
it will still scan all files as fallback.

Upgraded CI runner to Ubuntu 22.04 so we get clang-format 14 out of the box,
so we don't need to install a custom version (saves ~15 s). We also cache
the APT dependencies to speed up the build and avoid flaky Ubuntu/Microsoft
repos.

(cherry picked from commit 068f89307245d062bf2bf995de3726e33faef5d8)

5 files changed, 87 insertions, 37 deletions

diff --git a/.github/workflows/runner.yml b/.github/workflows/runner.yml
index 0487b1e090..be255b5468 100644
--- a/.github/workflows/runner.yml
+++ b/.github/workflows/runner.yml
@@ -7,7 +7,7 @@ concurrency:
 
 jobs:
   static-checks:
-    name: 📊 Static
+    name: 📊 Static checks
     uses: ./.github/workflows/static_checks.yml
 
   android-build:
diff --git a/.github/workflows/static_checks.yml b/.github/workflows/static_checks.yml
index b2ab913234..8ef49c4539 100644
--- a/.github/workflows/static_checks.yml
+++ b/.github/workflows/static_checks.yml
@@ -8,38 +8,58 @@ concurrency:
 
 jobs:
   static-checks:
-    name: Static Checks (clang-format, black format, file format, documentation checks)
-    runs-on: ubuntu-20.04
+    name: Code style, file formatting, and docs
+    runs-on: ubuntu-22.04
     steps:
       - name: Checkout
         uses: actions/checkout@v3
+        with:
+          fetch-depth: 2
+
+      - name: Install APT dependencies
+        uses: awalsh128/cache-apt-pkgs-action@latest
+        with:
+          packages: dos2unix libxml2-utils moreutils
 
-      - name: Install dependencies
+      - name: Install Python dependencies and general setup
         run: |
-          sudo rm -f /etc/apt/sources.list.d/microsoft-prod.list
-          wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
-          sudo apt-add-repository "deb http://apt.llvm.org/focal/ llvm-toolchain-focal-15 main"
-          sudo apt-get install -qq dos2unix clang-format-15 libxml2-utils python3-pip moreutils
-          sudo update-alternatives --remove-all clang-format || true
-          sudo update-alternatives --install /usr/bin/clang-format clang-format /usr/bin/clang-format-15 100
-          sudo pip3 install black==22.3.0 pytest==7.1.2 mypy==0.971
+          pip3 install black==22.3.0 pytest==7.1.2 mypy==0.971
           git config diff.wsErrorHighlight all
 
+      - name: Get changed files
+        id: changed-files
+        run: |
+          if [ "${{ github.event_name }}" == "pull_request" ]; then
+            files=$(git diff-tree --no-commit-id --name-only -r ${{ github.event.pull_request.base.sha }}..${{ github.event.pull_request.head.sha }} 2> /dev/null)
+          elif [ "${{ github.event_name }}" == "push" -a "${{ github.event.forced }}" == "false" -a "${{ github.event.created }}" == "false" ]; then
+            files=$(git diff-tree --no-commit-id --name-only -r ${{ github.event.before }}..${{ github.event.after }} 2> /dev/null)
+          fi
+          echo "$files" >> changed.txt
+          cat changed.txt
+
       - name: File formatting checks (file_format.sh)
         run: |
-          bash ./misc/scripts/file_format.sh
+          bash ./misc/scripts/file_format.sh changed.txt
 
       - name: Header guards formatting checks (header_guards.sh)
         run: |
-          bash ./misc/scripts/header_guards.sh
+          bash ./misc/scripts/header_guards.sh changed.txt
 
       - name: Python style checks via black (black_format.sh)
         run: |
-          bash ./misc/scripts/black_format.sh
+          if grep -qE '*\.py|SConstruct|SCsub' changed.txt || [ ! -s changed.txt ]; then
+            bash ./misc/scripts/black_format.sh
+          else
+            echo "Skipping Python formatting as no Python files were changed."
+          fi
 
       - name: Python scripts static analysis (mypy_check.sh)
         run: |
-          bash ./misc/scripts/mypy_check.sh
+          if grep -qE '*\.py|SConstruct|SCsub' changed.txt || [ ! -s changed.txt ]; then
+            bash ./misc/scripts/mypy_check.sh
+          else
+            echo "Skipping Python static analysis as no Python files were changed."
+          fi
 
       - name: Python builders checks via pytest (pytest_builders.sh)
         run: |
@@ -47,10 +67,14 @@ jobs:
 
       - name: JavaScript style and documentation checks via ESLint and JSDoc
         run: |
-          cd platform/web
-          npm ci
-          npm run lint
-          npm run docs -- -d dry-run
+          if grep -q "platform/web" changed.txt || [ ! -s changed.txt ]; then
+            cd platform/web
+            npm ci
+            npm run lint
+            npm run docs -- -d dry-run
+          else
+            echo "Skipping JavaScript formatting as no Web/JS files were changed."
+          fi
 
       - name: Class reference schema checks
         run: |
@@ -62,11 +86,16 @@ jobs:
 
       - name: Style checks via clang-format (clang_format.sh)
         run: |
-          bash ./misc/scripts/clang_format.sh
+          clang-format --version
+          bash ./misc/scripts/clang_format.sh changed.txt
 
       - name: Style checks via dotnet format (dotnet_format.sh)
         run: |
-          bash ./misc/scripts/dotnet_format.sh
+          if grep -q "modules/mono" changed.txt || [ ! -s changed.txt ]; then
+            bash ./misc/scripts/dotnet_format.sh
+          else
+            echo "Skipping dotnet format as no C# files were changed."
+          fi
 
       - name: Spell checks via codespell
         uses: codespell-project/actions-codespell@v1
diff --git a/misc/scripts/clang_format.sh b/misc/scripts/clang_format.sh
index 318a78b865..74a8e1a8a3 100755
--- a/misc/scripts/clang_format.sh
+++ b/misc/scripts/clang_format.sh
@@ -5,15 +5,22 @@
 
 set -uo pipefail
 
-# Loops through all code files tracked by Git.
-git ls-files -- '*.c' '*.h' '*.cpp' '*.hpp' '*.cc' '*.hh' '*.cxx' '*.m' '*.mm' '*.inc' '*.java' '*.glsl' \
+if [ $# -eq 0 ]; then
+    # Loop through all code files tracked by Git.
+    files=$(git ls-files -- '*.c' '*.h' '*.cpp' '*.hpp' '*.cc' '*.hh' '*.cxx' '*.m' '*.mm' '*.inc' '*.java' '*.glsl' \
                 ':!:.git/*' ':!:thirdparty/*' ':!:*/thirdparty/*' ':!:platform/android/java/lib/src/com/google/*' \
-                ':!:*-so_wrap.*' ':!:tests/python_build/*' |
-while read -r f; do
-    # Run clang-format.
-    clang-format --Wno-error=unknown -i "$f"
+                ':!:*-so_wrap.*' ':!:tests/python_build/*')
+else
+    # $1 should be a file listing file paths to process. Used in CI.
+    files=$(cat "$1" | grep -v "thirdparty/" | grep -E "\.(c|h|cpp|hpp|cc|hh|cxx|m|mm|inc|java|glsl)$" | grep -v "platform/android/java/lib/src/com/google/" | grep -v "\-so_wrap\." | grep -v "tests/python_build/")
+fi
+
+if [ ! -z "$files" ]; then
+    clang-format --Wno-error=unknown -i $files
+fi
 
-    # Fix copyright headers, but not all files get them.
+# Fix copyright headers, but not all files get them.
+for f in $files; do
     if [[ "$f" == *"inc" ]]; then
         continue
     elif [[ "$f" == *"glsl" ]]; then
diff --git a/misc/scripts/file_format.sh b/misc/scripts/file_format.sh
index f394c4ad3f..94a3affbd7 100755
--- a/misc/scripts/file_format.sh
+++ b/misc/scripts/file_format.sh
@@ -7,14 +7,20 @@
 # We need dos2unix and isutf8.
 if [ ! -x "$(command -v dos2unix)" -o ! -x "$(command -v isutf8)" ]; then
     printf "Install 'dos2unix' and 'isutf8' (moreutils package) to use this script.\n"
+    exit 1
 fi
 
 set -uo pipefail
-IFS=$'\n\t'
 
-# Loops through all text files tracked by Git.
-git grep -zIl '' |
-while IFS= read -rd '' f; do
+if [ $# -eq 0 ]; then
+    # Loop through all code files tracked by Git.
+    mapfile -d '' files < <(git grep -zIl '')
+else
+    # $1 should be a file listing file paths to process. Used in CI.
+    mapfile -d ' ' < <(cat "$1")
+fi
+
+for f in "${files[@]}"; do
     # Exclude some types of files.
     if [[ "$f" == *"csproj" ]]; then
         continue
diff --git a/misc/scripts/header_guards.sh b/misc/scripts/header_guards.sh
index a063ff4b9c..1f8aa6151c 100755
--- a/misc/scripts/header_guards.sh
+++ b/misc/scripts/header_guards.sh
@@ -5,9 +5,17 @@ if [ ! -f "version.py" ]; then
   echo "Some of the paths checks may not work as intended from a different folder."
 fi
 
+if [ $# -eq 0 ]; then
+    # Loop through all code files tracked by Git.
+    files=$(find -name "thirdparty" -prune -o -name "*.h" -print | sed "s@^\./@@g")
+else
+    # $1 should be a file listing file paths to process. Used in CI.
+    files=$(cat "$1" | grep -v "thirdparty/" | grep -E "\.h$" | sed "s@^\./@@g")
+fi
+
 files_invalid_guard=""
 
-for file in $(find -name "thirdparty" -prune -o -name "*.h" -print); do
+for file in $files; do
   # Skip *.gen.h and *-so_wrap.h, they're generated.
   if [[ "$file" == *".gen.h" || "$file" == *"-so_wrap.h" ]]; then continue; fi
   # Has important define before normal header guards.
@@ -20,16 +28,16 @@ for file in $(find -name "thirdparty" -prune -o -name "*.h" -print); do
   # Add custom prefix or suffix for generic filenames with a well-defined namespace.
 
   prefix=
-  if [[ "$file" == "./modules/"*"/register_types.h" ]]; then
+  if [[ "$file" == "modules/"*"/register_types.h" ]]; then
     module=$(echo $file | sed "s@.*modules/\([^/]*\).*@\1@")
     prefix="${module^^}_"
   fi
-  if [[ "$file" == "./platform/"*"/api/api.h" || "$file" == "./platform/"*"/export/"* ]]; then
+  if [[ "$file" == "platform/"*"/api/api.h" || "$file" == "platform/"*"/export/"* ]]; then
     platform=$(echo $file | sed "s@.*platform/\([^/]*\).*@\1@")
     prefix="${platform^^}_"
   fi
-  if [[ "$file" == "./modules/mono/utils/"* && "$bname" != *"mono"* ]]; then prefix="MONO_"; fi
-  if [[ "$file" == "./servers/rendering/storage/utilities.h" ]]; then prefix="RENDERER_"; fi
+  if [[ "$file" == "modules/mono/utils/"* && "$bname" != *"mono"* ]]; then prefix="MONO_"; fi
+  if [[ "$file" == "servers/rendering/storage/utilities.h" ]]; then prefix="RENDERER_"; fi
 
   suffix=
   if [[ "$file" == *"dummy"* && "$bname" != *"dummy"* ]]; then suffix="_DUMMY"; fi