From c609d284e0610b7dba19c2093fe96a7445bc6cae Mon Sep 17 00:00:00 2001
From: Markus Staab <maggus.staab@googlemail.com>
Date: Sun, 28 Sep 2025 11:14:39 +0200
Subject: [PATCH 1/2] Fix "Offset (int|string) might not exist on array" after
 `array_keys($arr)`

---
 src/Analyser/NodeScopeResolver.php              | 17 +++++++++++++++++
 ...NonexistentOffsetInArrayDimFetchRuleTest.php |  7 +++++++
 tests/PHPStan/Rules/Arrays/data/bug-12926.php   | 13 +++++++++++++
 3 files changed, 37 insertions(+)
 create mode 100644 tests/PHPStan/Rules/Arrays/data/bug-12926.php

diff --git a/src/Analyser/NodeScopeResolver.php b/src/Analyser/NodeScopeResolver.php
index c952da2e95..d5f87e3f15 100644
--- a/src/Analyser/NodeScopeResolver.php
+++ b/src/Analyser/NodeScopeResolver.php
@@ -6521,6 +6521,23 @@ private function enterForeach(MutatingScope $scope, MutatingScope $originalScope
 			}
 		}
 
+		if (
+			$stmt->expr instanceof FuncCall
+			&& $stmt->expr->name instanceof Name
+			&& $stmt->expr->name->toLowerString() === 'array_keys'
+			&& $stmt->valueVar instanceof Variable
+		) {
+			$args = $stmt->expr->getArgs();
+			if (count($args) >= 1) {
+				$arrayArg = $args[0]->value;
+				$scope = $scope->assignExpression(
+					new ArrayDimFetch($arrayArg, $stmt->valueVar),
+					$scope->getType($arrayArg)->getIterableValueType(),
+					$scope->getNativeType($arrayArg)->getIterableValueType(),
+				);
+			}
+		}
+
 		return $this->processVarAnnotation($scope, $vars, $stmt);
 	}
 
diff --git a/tests/PHPStan/Rules/Arrays/NonexistentOffsetInArrayDimFetchRuleTest.php b/tests/PHPStan/Rules/Arrays/NonexistentOffsetInArrayDimFetchRuleTest.php
index 48e9f1012d..6c79bcc795 100644
--- a/tests/PHPStan/Rules/Arrays/NonexistentOffsetInArrayDimFetchRuleTest.php
+++ b/tests/PHPStan/Rules/Arrays/NonexistentOffsetInArrayDimFetchRuleTest.php
@@ -1000,4 +1000,11 @@ public function testBug10492(): void
 		]);
 	}
 
+	public function testBug12926(): void
+	{
+		$this->reportPossiblyNonexistentGeneralArrayOffset = true;
+
+		$this->analyse([__DIR__ . '/data/bug-12926.php'], []);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Arrays/data/bug-12926.php b/tests/PHPStan/Rules/Arrays/data/bug-12926.php
new file mode 100644
index 0000000000..b5ffcae460
--- /dev/null
+++ b/tests/PHPStan/Rules/Arrays/data/bug-12926.php
@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+class HelloWorld
+{
+	public function sayHello(array $arr): void
+	{
+		foreach (array_keys($arr) as $key) {
+			var_dump($arr[$key]);
+		}
+	}
+}

From c8a2005e877ec937892acc5744472dcf46c607b2 Mon Sep 17 00:00:00 2001
From: Markus Staab <maggus.staab@googlemail.com>
Date: Sun, 28 Sep 2025 11:25:15 +0200
Subject: [PATCH 2/2] Update bug-12926.php

---
 tests/PHPStan/Rules/Arrays/data/bug-12926.php | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/PHPStan/Rules/Arrays/data/bug-12926.php b/tests/PHPStan/Rules/Arrays/data/bug-12926.php
index b5ffcae460..d83bd21b36 100644
--- a/tests/PHPStan/Rules/Arrays/data/bug-12926.php
+++ b/tests/PHPStan/Rules/Arrays/data/bug-12926.php
@@ -1,6 +1,6 @@
-<?php
+<?php declare(strict_types=1);
 
-declare(strict_types=1);
+namespace Bug12926;
 
 class HelloWorld
 {