Fix #1886 - allow empty array to be coerced to a mixed one

src/Psalm/Internal/Analyzer/TypeAnalyzer.php

@@ -1789,6 +1789,7 @@ class TypeAnalyzer
                     && !$container_param->hasTemplate()
                     && !$input_param->hasTemplate()
                     && !$input_param->hasLiteralValue()
+                    && !$input_param->hasEmptyArray()
                 ) {
                     $input_storage = $codebase->classlike_storage_provider->get($input_type_part->value);
 

src/Psalm/Type/Union.php

@@ -569,6 +569,16 @@ class Union
         return isset($this->types['array']);
     }
 
+    /**
+     * @return bool
+     */
+    public function hasEmptyArray()
+    {
+        return isset($this->types['array'])
+            && $this->types['array'] instanceof Atomic\TArray
+            && $this->types['array']->type_params[1]->isEmpty();
+    }
+
     /**
      * @return bool
      */

tests/Template/ClassTemplateTest.php

@@ -1601,6 +1601,23 @@ class ClassTemplateTest extends TestCase
                         return new TestPromise(true);
                     }',
             ],
+            'classTemplatedPropertyEmptyAssignment' => [
+                '<?php
+                    /** @template T */
+                    class Foo {
+                        /** @param \Closure():T $closure */
+                        public function __construct($closure) {}
+                    }
+
+                    class Bar {
+                        /** @var Foo<array> */
+                        private $FooArray;
+
+                        public function __construct() {
+                            $this->FooArray = new Foo(function(): array { return []; });
+                        }
+                    }',
+            ],
         ];
     }