From f40b6625ebc2525901211a1f5fa86616849e00b4 Mon Sep 17 00:00:00 2001
From: Matthew Brown <github@muglug.com>
Date: Fri, 13 Dec 2019 21:40:09 -0500
Subject: [PATCH] Fix #2431 - allow null in template defaults

---
 .../Analyzer/FunctionLikeAnalyzer.php         |  4 ++--
 src/Psalm/Internal/Analyzer/TypeAnalyzer.php  |  2 +-
 .../Internal/Visitor/ReflectorVisitor.php     |  5 ++++-
 tests/Template/FunctionTemplateTest.php       | 22 +++++++++++++++++++
 4 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/src/Psalm/Internal/Analyzer/FunctionLikeAnalyzer.php b/src/Psalm/Internal/Analyzer/FunctionLikeAnalyzer.php
index ab7c5f968..47192abcf 100644
--- a/src/Psalm/Internal/Analyzer/FunctionLikeAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/FunctionLikeAnalyzer.php
@@ -1041,9 +1041,9 @@ abstract class FunctionLikeAnalyzer extends SourceAnalyzer
                 ) {
                     if (IssueBuffer::accepts(
                         new InvalidParamDefault(
-                            'Default value type ' . $default_type . ' for argument ' . ($offset + 1)
+                            'Default value type ' . $default_type->getId() . ' for argument ' . ($offset + 1)
                                 . ' of method ' . $cased_method_id
-                                . ' does not match the given type ' . $param_type,
+                                . ' does not match the given type ' . $param_type->getId(),
                             $function_param->type_location
                         )
                     )) {
diff --git a/src/Psalm/Internal/Analyzer/TypeAnalyzer.php b/src/Psalm/Internal/Analyzer/TypeAnalyzer.php
index f8036e7fb..b1f7b1678 100644
--- a/src/Psalm/Internal/Analyzer/TypeAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/TypeAnalyzer.php
@@ -733,7 +733,7 @@ class TypeAnalyzer
             }
 
             if ($container_type_part instanceof TTemplateParam
-                && $container_type_part->as->isNullable()
+                && ($container_type_part->as->isNullable() || $container_type_part->as->isMixed())
             ) {
                 return true;
             }
diff --git a/src/Psalm/Internal/Visitor/ReflectorVisitor.php b/src/Psalm/Internal/Visitor/ReflectorVisitor.php
index b63f7d44d..89024f259 100644
--- a/src/Psalm/Internal/Visitor/ReflectorVisitor.php
+++ b/src/Psalm/Internal/Visitor/ReflectorVisitor.php
@@ -2953,7 +2953,10 @@ class ReflectorVisitor extends PhpParser\NodeVisitorAbstract implements PhpParse
             $existing_param_type_nullable = $storage_param->is_nullable;
 
             if (!$storage_param->type || $storage_param->type->hasMixed() || $storage->template_types) {
-                if ($existing_param_type_nullable && !$new_param_type->isNullable()) {
+                if ($existing_param_type_nullable
+                    && !$new_param_type->isNullable()
+                    && !$new_param_type->hasTemplate()
+                ) {
                     $new_param_type->addType(new Type\Atomic\TNull());
                 }
 
diff --git a/tests/Template/FunctionTemplateTest.php b/tests/Template/FunctionTemplateTest.php
index 9a7424367..9e861edc1 100644
--- a/tests/Template/FunctionTemplateTest.php
+++ b/tests/Template/FunctionTemplateTest.php
@@ -856,6 +856,28 @@ class FunctionTemplateTest extends TestCase
                         }
                     }'
             ],
+            'falseDefault' => [
+                '<?php
+                    /**
+                     * @template T
+                     * @param T $v
+                     * @return T
+                     */
+                    function exampleWithNullDefault($v = false) {
+                       return $v;
+                    }'
+            ],
+            'nullDefault' => [
+                '<?php
+                    /**
+                     * @template T
+                     * @param T $v
+                     * @return T
+                     */
+                    function exampleWithNullDefault($v = null) {
+                       return $v;
+                    }'
+            ],
         ];
     }