From 3dfe74f70d60be7fc00879b1fd35640e45a8b980 Mon Sep 17 00:00:00 2001
From: phpstan-bot <79867460+phpstan-bot@users.noreply.github.com>
Date: Tue, 28 Apr 2026 17:41:16 +0000
Subject: [PATCH] Preserve conditional expressions in `invalidateExpression`
 when `requireMoreCharacters` is true

- In `MutatingScope::invalidateExpression()`, the target expression check for
  conditional expressions was hardcoded to `requireMoreCharacters=false`, causing
  conditional expressions to be removed even when the expression type itself was
  preserved (e.g. after a method call on the variable)
- Pass the caller's `$requireMoreCharacters` flag to the `shouldInvalidateExpression`
  check for conditional expression targets, consistent with the expression type check
- This fixes stored `instanceof` results losing their type narrowing after the first
  use when the if-block body contains impure calls (method calls, var_dump, etc.)
- The bug only manifested for concrete class types (e.g. `ObjectClass`) where
  `createConditionalExpressions` could not reconstruct the conditional from type
  differences, unlike abstract `object` types where it could
---
 src/Analyser/MutatingScope.php            |   2 +-
 tests/PHPStan/Analyser/nsrt/bug-14545.php | 112 ++++++++++++++++++++++
 2 files changed, 113 insertions(+), 1 deletion(-)
 create mode 100644 tests/PHPStan/Analyser/nsrt/bug-14545.php

diff --git a/src/Analyser/MutatingScope.php b/src/Analyser/MutatingScope.php
index 79d4be017bf..64e46074738 100644
--- a/src/Analyser/MutatingScope.php
+++ b/src/Analyser/MutatingScope.php
@@ -2869,7 +2869,7 @@ public function invalidateExpression(Expr $expressionToInvalidate, bool $require
 				continue;
 			}
 			$firstExpr = $holders[array_key_first($holders)]->getTypeHolder()->getExpr();
-			if ($this->shouldInvalidateExpression($exprStringToInvalidate, $expressionToInvalidate, $firstExpr, $this->getNodeKey($firstExpr), false, $invalidatingClass)) {
+			if ($this->shouldInvalidateExpression($exprStringToInvalidate, $expressionToInvalidate, $firstExpr, $this->getNodeKey($firstExpr), $requireMoreCharacters, $invalidatingClass)) {
 				$invalidated = true;
 				continue;
 			}
diff --git a/tests/PHPStan/Analyser/nsrt/bug-14545.php b/tests/PHPStan/Analyser/nsrt/bug-14545.php
new file mode 100644
index 00000000000..e12b2e9df1b
--- /dev/null
+++ b/tests/PHPStan/Analyser/nsrt/bug-14545.php
@@ -0,0 +1,112 @@
+<?php
+
+declare(strict_types = 1);
+
+namespace Bug14545;
+
+use function PHPStan\Testing\assertType;
+
+interface SomeInterface {
+	public function test(): void;
+}
+
+class ObjectClass {
+}
+
+class OtherClass {
+}
+
+/**
+ * @template T of object
+ * @param class-string<T> $class_name
+ * @return T
+ */
+function getObject1(string $class_name): object {
+	return new $class_name;
+}
+
+function testStoredInstanceofWithGenericMethodCall(): void {
+	$obj = getObject1(ObjectClass::class);
+	$is_interface = $obj instanceof SomeInterface;
+	if($is_interface) {
+		assertType('Bug14545\ObjectClass&Bug14545\SomeInterface', $obj);
+		$obj->test();
+	}
+
+	if($is_interface) {
+		assertType('Bug14545\ObjectClass&Bug14545\SomeInterface', $obj);
+		$obj->test();
+	}
+}
+
+function testStoredInstanceofWithGenericFuncCall(): void {
+	$obj = getObject1(ObjectClass::class);
+	$is_interface = $obj instanceof SomeInterface;
+	if($is_interface) {
+		var_dump($obj);
+	}
+
+	if($is_interface) {
+		assertType('Bug14545\ObjectClass&Bug14545\SomeInterface', $obj);
+	}
+}
+
+function testStoredInstanceofWithConcreteClass(): void {
+	$obj = getObject1(OtherClass::class);
+	$is_interface = $obj instanceof SomeInterface;
+	if($is_interface) {
+		assertType('Bug14545\OtherClass&Bug14545\SomeInterface', $obj);
+		$obj->test();
+	}
+
+	if($is_interface) {
+		assertType('Bug14545\OtherClass&Bug14545\SomeInterface', $obj);
+	}
+}
+
+function getObject2(): object {
+	return new \stdClass();
+}
+
+function testStoredInstanceofWithAbstractObject(): void {
+	$obj = getObject2();
+	$is_interface = $obj instanceof SomeInterface;
+	if($is_interface) {
+		assertType('Bug14545\SomeInterface', $obj);
+		$obj->test();
+	}
+
+	if($is_interface) {
+		assertType('Bug14545\SomeInterface', $obj);
+		$obj->test();
+	}
+}
+
+function testThreeConsecutiveChecks(): void {
+	$obj = getObject1(ObjectClass::class);
+	$is_interface = $obj instanceof SomeInterface;
+	if($is_interface) {
+		$obj->test();
+	}
+	if($is_interface) {
+		$obj->test();
+	}
+	if($is_interface) {
+		assertType('Bug14545\ObjectClass&Bug14545\SomeInterface', $obj);
+	}
+}
+
+/**
+ * @param array<mixed, mixed> $data
+ */
+function testStoredIsArray(array $data): void {
+	$value = $data['key'] ?? null;
+	$isArray = is_array($value);
+	if ($isArray) {
+		assertType('array<mixed, mixed>', $value);
+		var_dump($value);
+	}
+	if ($isArray) {
+		assertType('array<mixed, mixed>', $value);
+	}
+}