Add configuration for PHPCS

And execute it on Travis (allowing it to fail for now to prevent a lot
of conflicts with `develop`).

.gitattributes

@@ -10,3 +10,4 @@ build.xml export-ignore
 CONTRIBUTING.md export-ignore
 phpunit.xml.dist export-ignore
 run-all.sh export-ignore
+phpcs.xml.dist export-ignore

.gitignore

@@ -13,3 +13,4 @@ lib/Doctrine/DBAL
 vendor/
 composer.lock
 /tests/Doctrine/Performance/history.db
+/.phpcs-cache

.travis.yml

@@ -78,6 +78,11 @@ jobs:
       before_script: wget https://phpbench.github.io/phpbench/phpbench.phar https://phpbench.github.io/phpbench/phpbench.phar.pubkey
       script: php phpbench.phar run -l dots --report=default
 
+    - stage: Coding standard
+      php: nightly
+      script:
+        - ./vendor/bin/phpcs
+
   allow_failures:
     - php: nightly
 

composer.json

@@ -28,7 +28,9 @@
         "symfony/console": "~3.0|~4.0"
     },
     "require-dev": {
+        "doctrine/coding-standard": "^1.0",
         "phpunit/phpunit": "^6.0",
+        "squizlabs/php_codesniffer": "^3.1",
         "symfony/yaml": "~3.4|~4.0"
     },
     "suggest": {

phpcs.xml.dist

@@ -0,0 +1,24 @@
+<?xml version="1.0"?>
+<ruleset>
+    <arg name="basepath" value="."/>
+    <arg name="extensions" value="php"/>
+    <arg name="parallel" value="80"/>
+    <arg name="cache" value=".phpcs-cache"/>
+    <arg name="colors" />
+
+    <!-- Ignore warnings and show progress of the run -->
+    <arg value="np"/>
+
+    <file>lib</file>
+    <file>tests</file>
+    <file>tools</file>
+
+    <exclude-pattern>*/tests/Doctrine/Tests/Proxies/__CG__/*</exclude-pattern>
+
+    <rule ref="Doctrine" />
+
+    <rule ref="PSR1.Classes.ClassDeclaration.MultipleClasses">
+        <exclude-pattern>*/tests/*</exclude-pattern>
+    </rule>
+</ruleset>
+