Fix support for Closure(int):int annotation

src/Psalm/Type.php

@@ -292,7 +292,7 @@ abstract class Type
         if ($parse_tree instanceof ParseTree\CallableWithReturnTypeTree) {
             $callable_type = self::getTypeFromTree($parse_tree->children[0], false);
 
-            if (!$callable_type instanceof TCallable) {
+            if (!$callable_type instanceof TCallable && !$callable_type instanceof Type\Atomic\Fn) {
                 throw new \InvalidArgumentException('Parsing callable tree node should return TCallable');
             }
 
@@ -336,7 +336,7 @@ abstract class Type
                 $parse_tree->children
             );
 
-            if (in_array($parse_tree->value, ['closure', '\closure'], false)) {
+            if (in_array(strtolower($parse_tree->value), ['closure', '\closure'], true)) {
                 return new Type\Atomic\Fn('Closure', $params);
             }
 

src/Psalm/Type/Atomic/CallableTrait.php

@@ -93,4 +93,20 @@ trait CallableTrait
 
         return 'callable' . $param_string . $return_type_string;
     }
+
+    public function getId()
+    {
+        $param_string = '';
+        $return_type_string = '';
+
+        if ($this->params !== null) {
+            $param_string = '(' . implode(', ', $this->params) . ')';
+        }
+
+        if ($this->return_type !== null) {
+            $return_type_string = ' : ' . $this->return_type;
+        }
+
+        return $this->value . $param_string . $return_type_string;
+    }
 }

src/Psalm/Type/ParseTree.php

@@ -322,7 +322,7 @@ class ParseTree
                             break;
 
                         case '(':
-                            if (!in_array($type_token, ['closure', 'callable', '\closure'])) {
+                            if (!in_array(strtolower($type_token), ['closure', 'callable', '\closure'])) {
                                 throw new TypeParseTreeException(
                                     'Bracket must be preceded by “Closure” or “callable”'
                                 );

src/Psalm/Visitor/DependencyFinderVisitor.php

@@ -597,6 +597,7 @@ class DependencyFinderVisitor extends PhpParser\NodeVisitorAbstract implements P
             $function_id = strtolower($cased_function_id);
 
             if ($this->codebase->register_global_functions) {
+
                 $storage = new FunctionLikeStorage();
                 $this->codebase->functions->addStubbedFunction($function_id, $storage);
             } else {

tests/CallableTest.php

@@ -293,6 +293,19 @@ class CallableTest extends TestCase
                       [1, 2, 3]
                     );',
             ],
+            'returnsTypedClosure' => [
+                '<?php
+                    /**
+                     * @param Closure(int):int $f
+                     * @param Closure(int):int $g
+                     * @return Closure(int):int
+                     */
+                    function foo(Closure $f, Closure $g) : Closure {
+                        return function (int $x) use ($f, $g) : int {
+                            return $f($g($x));
+                        }
+                    }'
+            ],
         ];
     }