From b4f03abca627bf99706c41d109a6d15c6a0cb0b3 Mon Sep 17 00:00:00 2001
From: Matthew Brown <github@muglug.com>
Date: Fri, 5 Jul 2019 17:44:22 -0400
Subject: [PATCH] Fix #1886 - allow empty array to be coerced to a mixed one

---
 src/Psalm/Internal/Analyzer/TypeAnalyzer.php |  1 +
 src/Psalm/Type/Union.php                     | 10 ++++++++++
 tests/Template/ClassTemplateTest.php         | 17 +++++++++++++++++
 3 files changed, 28 insertions(+)

diff --git a/src/Psalm/Internal/Analyzer/TypeAnalyzer.php b/src/Psalm/Internal/Analyzer/TypeAnalyzer.php
index e12ebf474..2fa0389b4 100644
--- a/src/Psalm/Internal/Analyzer/TypeAnalyzer.php
+++ b/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);
 
diff --git a/src/Psalm/Type/Union.php b/src/Psalm/Type/Union.php
index 5fac2833e..7af6a240f 100644
--- a/src/Psalm/Type/Union.php
+++ b/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
      */
diff --git a/tests/Template/ClassTemplateTest.php b/tests/Template/ClassTemplateTest.php
index ca0f683d7..24240fee7 100644
--- a/tests/Template/ClassTemplateTest.php
+++ b/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 []; });
+                        }
+                    }',
+            ],
         ];
     }