Update to Psalm 4

Author: sebastianbergmann

.github/workflows/ci.yml

@@ -32,7 +32,7 @@ jobs:
         run: "php7.3 ./tools/composer update --no-ansi --no-interaction --no-progress"
 
       - name: "Run vimeo/psalm"
-        run: "php7.3 ./tools/psalm --config=psalm.xml --no-progress --shepherd --show-info=false --stats"
+        run: "php7.3 ./tools/psalm --config=.psalm/config.xml --no-progress --shepherd --show-info=false --stats"
 
   backward-compatibility:
     name: Backward Compatibility

.phive/phars.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <phive xmlns="https://phar.io/phive">
   <phar name="php-cs-fixer" version="^2.16" installed="2.16.4" location="./tools/php-cs-fixer" copy="true"/>
-  <phar name="psalm" version="^3.8" installed="3.18.2" location="./tools/psalm" copy="true"/>
+  <phar name="psalm" version="^4.0" installed="4.0.1" location="./tools/psalm" copy="true"/>
   <phar name="roave/backwardcompatibilitycheck" version="^5.0.0" installed="5.0.0" location="./tools/roave-backward-compatibility-check" copy="true"/>
 </phive>

.psalm/baseline.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<files psalm-version="4.0.1@b1e2e30026936ef8d5bf6a354d1c3959b6231f44">
+  <file src="src/Enumerator.php">
+    <DocblockTypeContradiction occurrences="2">
+      <code>!is_array($variable) &amp;&amp; !is_object($variable)</code>
+      <code>is_object($variable)</code>
+    </DocblockTypeContradiction>
+  </file>
+</files>

.psalm/config.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0"?>
+<psalm
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xmlns="https://getpsalm.org/schema/config"
+    xsi:schemaLocation="https://getpsalm.org/schema/config vendor/vimeo/psalm/config.xsd"
+    resolveFromConfigFile="false"
+    totallyTyped="false"
+    errorBaseline=".psalm/baseline.xml"
+>
+    <projectFiles>
+        <directory name="src" />
+        <ignoreFiles>
+            <directory name="vendor" />
+        </ignoreFiles>
+    </projectFiles>
+</psalm>