Add PHPStan to QA checks

.gitattributes

@@ -8,6 +8,7 @@
 /.gitattributes            export-ignore
 /.gitignore                export-ignore
 /.phpcs.xml.dist           export-ignore
+/phpstan.neon.dist         export-ignore
 /phpunit.xml.dist          export-ignore
 /.github                   export-ignore
 /bin                       export-ignore

.github/workflows/basics.yml

@@ -76,3 +76,31 @@ jobs:
       # At a later stage the documentation check can be activated.
       - name: Check sniff feature completeness
         run: composer feature-completeness
+
+  phpstan:
+    name: "PHPStan"
+
+    runs-on: "ubuntu-latest"
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v3
+
+      - name: Install PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: '7.4'
+          coverage: none
+          tools: phpstan
+
+      # Install dependencies and handle caching in one go.
+      # Dependencies need to be installed to make sure the PHPCS and PHPUnit classes are recognized.
+      # @link https://github.com/marketplace/actions/install-composer-dependencies
+      - name: Install Composer dependencies
+        uses: "ramsey/composer-install@v2"
+        with:
+          # Bust the cache at least once a month - output format: YYYY-MM.
+          custom-cache-suffix: $(date -u "+%Y-%m")
+
+      - name: Run PHPStan
+        run: phpstan analyse

.gitignore

@@ -5,3 +5,4 @@ phpcs.xml
 .phpcs.xml
 phpunit.xml
 phpcs.cache
+phpstan.neon

phpstan.neon.dist

@@ -0,0 +1,13 @@
+parameters:
+    #phpVersion: 50400 # Needs to be 70100 or higher... sigh...
+    level: 5
+    paths:
+        - WordPressVIPMinimum
+        - tests
+    bootstrapFiles:
+        - tests/bootstrap.php
+    scanDirectories:
+        - vendor/wp-coding-standards/wpcs/WordPress
+    treatPhpDocTypesAsCertain: false
+
+    ignoreErrors: