From 052599192ab53ea522b9d9deb50c7dba2a47a912 Mon Sep 17 00:00:00 2001
From: Matthew Brown <github@muglug.com>
Date: Sat, 25 May 2019 12:44:47 -0400
Subject: [PATCH] Fix #1680 - narrow nullable templated matching

---
 src/Psalm/Type/Union.php        |  6 ++++++
 tests/Template/TemplateTest.php | 22 ++++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/src/Psalm/Type/Union.php b/src/Psalm/Type/Union.php
index 2c5aff139..fb9740d59 100644
--- a/src/Psalm/Type/Union.php
+++ b/src/Psalm/Type/Union.php
@@ -1009,10 +1009,16 @@ class Union
 
                         if ($input_type) {
                             $generic_param = clone $input_type;
+
+                            if ($this->isNullable() && $generic_param->isNullable()) {
+                                $generic_param->removeType('null');
+                            }
+
                             $generic_param->setFromDocblock();
 
                             if (isset($generic_params[$key][$atomic_type->defining_class ?: ''][0])) {
                                 $existing_depth = $generic_params[$key][$atomic_type->defining_class ?: ''][1] ?? -1;
+
                                 if ($existing_depth > $depth) {
                                     continue;
                                 }
diff --git a/tests/Template/TemplateTest.php b/tests/Template/TemplateTest.php
index f6405e6c6..158604ec6 100644
--- a/tests/Template/TemplateTest.php
+++ b/tests/Template/TemplateTest.php
@@ -2572,6 +2572,28 @@ class TemplateTest extends TestCase
                         return get(B::class, $mapB, $id);
                     }'
             ],
+            'dontGeneraliseBoundParamWithWiderCallable' => [
+                '<?php
+                    class C {
+                        public function foo() : void {}
+                    }
+
+                    /**
+                     * @psalm-template T
+                     * @psalm-param T $t
+                     * @psalm-param callable(?T):void $callable
+                     * @return T
+                     */
+                    function makeConcrete($t, callable $callable) {
+                        $callable(rand(0, 1) ? $t : null);
+                        return $t;
+                    }
+
+                    $c = makeConcrete(new C(), function (?C $c) : void {});',
+                [
+                    '$c' => 'C',
+                ]
+            ],
         ];
     }