Fix infinite loop when fully qualified callback is supplied

This seemed to only cause a problem when running the code on PHP 7
and where the same file contained a native call to the same callback
function.

Example:

  <?php
  \array_filter([1], '\\is_int');
  \is_int(1);

src/Type/Php/ArrayFilterFunctionReturnTypeReturnTypeExtension.php

@@ -33,6 +33,7 @@
 use function count;
 use function is_string;
 use function strtolower;
+use function substr;
 
 class ArrayFilterFunctionReturnTypeReturnTypeExtension implements DynamicFunctionReturnTypeExtension
 {
@@ -83,7 +84,7 @@ public function getTypeFromFunctionCall(FunctionReflection $functionReflection,
 				return $this->filterByTruthyValue($scope, $callbackArg->params[0]->var, $arrayArgType, null, $callbackArg->expr);
 			} elseif ($callbackArg instanceof String_) {
 				$itemVar = new Variable('item');
-				$expr = new FuncCall(new Name($callbackArg->value), [new Arg($itemVar)]);
+				$expr = new FuncCall(self::createFunctionName($callbackArg->value), [new Arg($itemVar)]);
 				return $this->filterByTruthyValue($scope, $itemVar, $arrayArgType, null, $expr);
 			}
 		}
@@ -98,7 +99,7 @@ public function getTypeFromFunctionCall(FunctionReflection $functionReflection,
 				return $this->filterByTruthyValue($scope, null, $arrayArgType, $callbackArg->params[0]->var, $callbackArg->expr);
 			} elseif ($callbackArg instanceof String_) {
 				$keyVar = new Variable('key');
-				$expr = new FuncCall(new Name($callbackArg->value), [new Arg($keyVar)]);
+				$expr = new FuncCall(self::createFunctionName($callbackArg->value), [new Arg($keyVar)]);
 				return $this->filterByTruthyValue($scope, null, $arrayArgType, $keyVar, $expr);
 			}
 		}
@@ -114,7 +115,7 @@ public function getTypeFromFunctionCall(FunctionReflection $functionReflection,
 			} elseif ($callbackArg instanceof String_) {
 				$itemVar = new Variable('item');
 				$keyVar = new Variable('key');
-				$expr = new FuncCall(new Name($callbackArg->value), [new Arg($itemVar), new Arg($keyVar)]);
+				$expr = new FuncCall(self::createFunctionName($callbackArg->value), [new Arg($itemVar), new Arg($keyVar)]);
 				return $this->filterByTruthyValue($scope, $itemVar, $arrayArgType, $keyVar, $expr);
 			}
 		}
@@ -234,4 +235,13 @@ private function processKeyAndItemType(MutatingScope $scope, Type $keyType, Type
 		];
 	}
 
+	private static function createFunctionName(string $funcName): Name
+	{
+		if ($funcName[0] === '\\') {
+			return new Name\FullyQualified(substr($funcName, 1));
+		}
+
+		return new Name($funcName);
+	}
+
 }

tests/PHPStan/Analyser/AnalyserIntegrationTest.php

@@ -1025,6 +1025,12 @@ public function testBug7110(): void
 		$this->assertSame(30, $errors[0]->getLine());
 	}
 
+	public function testBug8376(): void
+	{
+		$errors = $this->runAnalyse(__DIR__ . '/data/bug-8376.php');
+		$this->assertNoErrors($errors);
+	}
+
 	public function testAssertDocblock(): void
 	{
 		$errors = $this->runAnalyse(__DIR__ . '/data/assert-docblock.php');

tests/PHPStan/Analyser/data/bug-8376.php

@@ -0,0 +1,11 @@
+<?php declare(strict_types=1);
+
+namespace Bug8376;
+
+function (array $arr): array {
+    return array_filter($arr, '\\is_int');
+};
+
+function ($var): void {
+    \assert(\is_int($var));
+};