From b19dd25881b00842ba243e3d41d517420a8e8332 Mon Sep 17 00:00:00 2001
From: Matthew Brown <github@muglug.com>
Date: Sun, 6 Jan 2019 12:16:09 -0500
Subject: [PATCH] Fix #742 - infer template type from closure

---
 .../Statements/Expression/CallAnalyzer.php    | 14 ++++-
 src/Psalm/Type/Atomic.php                     |  2 +-
 src/Psalm/Type/Atomic/CallableTrait.php       |  5 +-
 src/Psalm/Type/Atomic/GenericTrait.php        |  2 +-
 src/Psalm/Type/Union.php                      |  8 ++-
 tests/TemplateTest.php                        | 57 +++++++++++++++++++
 6 files changed, 79 insertions(+), 9 deletions(-)

diff --git a/src/Psalm/Internal/Analyzer/Statements/Expression/CallAnalyzer.php b/src/Psalm/Internal/Analyzer/Statements/Expression/CallAnalyzer.php
index 42399957e..bbcb5fe72 100644
--- a/src/Psalm/Internal/Analyzer/Statements/Expression/CallAnalyzer.php
+++ b/src/Psalm/Internal/Analyzer/Statements/Expression/CallAnalyzer.php
@@ -834,9 +834,17 @@ class CallAnalyzer
             if ($class_storage && $class_storage->template_types) {
                 $template_types = array_merge($template_types, $class_storage->template_types);
             }
+
+            foreach ($template_types as $key => $type) {
+                $template_types[$key] = clone $type;
+            }
         }
 
-        $existing_generic_params_to_strings = $generic_params ?: [];
+        $existing_generic_params = $generic_params ?: [];
+
+        foreach ($existing_generic_params as $key => $type) {
+            $existing_generic_params[$key] = clone $type;
+        }
 
         foreach ($args as $argument_offset => $arg) {
             $function_param = count($function_params) > $argument_offset
@@ -952,11 +960,11 @@ class CallAnalyzer
                     }
 
                     if ($function_storage) {
-                        if ($existing_generic_params_to_strings) {
+                        if ($existing_generic_params) {
                             $empty_generic_params = [];
 
                             $param_type->replaceTemplateTypesWithStandins(
-                                $existing_generic_params_to_strings,
+                                $existing_generic_params,
                                 $empty_generic_params,
                                 $codebase,
                                 $arg->value->inferredType
diff --git a/src/Psalm/Type/Atomic.php b/src/Psalm/Type/Atomic.php
index 6d817b74e..b1e78bf1f 100644
--- a/src/Psalm/Type/Atomic.php
+++ b/src/Psalm/Type/Atomic.php
@@ -517,7 +517,7 @@ abstract class Atomic
      * @return void
      */
     public function replaceTemplateTypesWithStandins(
-        array $template_types,
+        array &$template_types,
         array &$generic_params,
         Codebase $codebase = null,
         Type\Atomic $input_type = null
diff --git a/src/Psalm/Type/Atomic/CallableTrait.php b/src/Psalm/Type/Atomic/CallableTrait.php
index 8976a0fb5..dfd975750 100644
--- a/src/Psalm/Type/Atomic/CallableTrait.php
+++ b/src/Psalm/Type/Atomic/CallableTrait.php
@@ -166,7 +166,7 @@ trait CallableTrait
      * @return void
      */
     public function replaceTemplateTypesWithStandins(
-        array $template_types,
+        array &$template_types,
         array &$generic_params,
         Codebase $codebase = null,
         Atomic $input_type = null
@@ -189,7 +189,8 @@ trait CallableTrait
                     $template_types,
                     $generic_params,
                     $codebase,
-                    $input_param_type
+                    $input_param_type,
+                    true
                 );
             }
         }
diff --git a/src/Psalm/Type/Atomic/GenericTrait.php b/src/Psalm/Type/Atomic/GenericTrait.php
index 2dd9c5596..455048d97 100644
--- a/src/Psalm/Type/Atomic/GenericTrait.php
+++ b/src/Psalm/Type/Atomic/GenericTrait.php
@@ -146,7 +146,7 @@ trait GenericTrait
      * @return void
      */
     public function replaceTemplateTypesWithStandins(
-        array $template_types,
+        array &$template_types,
         array &$generic_params,
         Codebase $codebase = null,
         Atomic $input_type = null
diff --git a/src/Psalm/Type/Union.php b/src/Psalm/Type/Union.php
index c17cd0238..a5352e590 100644
--- a/src/Psalm/Type/Union.php
+++ b/src/Psalm/Type/Union.php
@@ -789,10 +789,11 @@ class Union
      * @return void
      */
     public function replaceTemplateTypesWithStandins(
-        array $template_types,
+        array &$template_types,
         array &$generic_params,
         Codebase $codebase = null,
-        Type\Union $input_type = null
+        Type\Union $input_type = null,
+        bool $add_upper_bound = false
     ) {
         $keys_to_unset = [];
 
@@ -802,6 +803,9 @@ class Union
             ) {
                 if ($template_types[$key]->getId() !== $key) {
                     $first_atomic_type = array_values($template_types[$key]->getTypes())[0];
+                    if ($add_upper_bound && $input_type) {
+                        $template_types[$key] = clone $input_type;
+                    }
                     $this->types[$first_atomic_type->getKey()] = clone $first_atomic_type;
                     if ($first_atomic_type->getKey() !== $key) {
                         $keys_to_unset[] = $key;
diff --git a/tests/TemplateTest.php b/tests/TemplateTest.php
index 3ac506ddc..d19ae3b1f 100644
--- a/tests/TemplateTest.php
+++ b/tests/TemplateTest.php
@@ -1141,6 +1141,28 @@ class TemplateTest extends TestCase
                 'assertions' => [],
                 'error_levels' => [],
             ],
+            'bindFirstTemplatedClosureParameter' => [
+                '<?php
+                    /**
+                     * @template T
+                     *
+                     * @param Closure(T):void $t1
+                     * @param T $t2
+                     */
+                    function apply(Closure $t1, $t2) : void
+                    {
+                        $t1($t2);
+                    }
+
+                    apply(function(int $_i) : void {}, 5);
+                    apply(function(string $_i) : void {}, "hello");
+                    apply(function(stdClass $_i) : void {}, new stdClass);
+
+                    class A {}
+                    class AChild extends A {}
+
+                    apply(function(A $_i) : void {}, new AChild());',
+            ],
         ];
     }
 
@@ -1412,6 +1434,41 @@ class TemplateTest extends TestCase
                     }',
                 'error_message' => 'MixedTypeCoercion',
             ],
+            'bindFirstTemplatedClosureParameter' => [
+                '<?php
+                    /**
+                     * @template T
+                     *
+                     * @param Closure(T):void $t1
+                     * @param T $t2
+                     */
+                    function apply(Closure $t1, $t2) : void
+                    {
+                        $t1($t2);
+                    }
+
+                    apply(function(int $_i) : void {}, "hello");',
+                'error_message' => 'InvalidScalarArgument',
+            ],
+            'bindFirstTemplatedClosureParameterTypeCoercion' => [
+                '<?php
+                    /**
+                     * @template T
+                     *
+                     * @param Closure(T):void $t1
+                     * @param T $t2
+                     */
+                    function apply(Closure $t1, $t2) : void
+                    {
+                        $t1($t2);
+                    }
+
+                    class A {}
+                    class AChild extends A {}
+
+                    apply(function(AChild $_i) : void {}, new A());',
+                'error_message' => 'TypeCoercion',
+            ],
         ];
     }
 }