Process match arm condition before analysing the body

src/Analyser/NodeScopeResolver.php

@@ -2884,7 +2884,8 @@ static function (Node $node, Scope $scope) use ($nodeCallback): void {
 					);
 				}
 
-				$bodyScope = $matchScope->filterByTruthyValue($filteringExpr);
+				$bodyScope = $this->processExprNode($stmt, $filteringExpr, $matchScope, static function (): void {
+				}, $deepContext)->getTruthyScope();
 				$matchArmBody = new MatchExpressionArmBody($bodyScope, $arm->body);
 				$armNodes[] = new MatchExpressionArm($matchArmBody, $condNodes, $arm->getLine());
 

tests/PHPStan/Rules/Variables/DefinedVariableRuleTest.php

@@ -1029,4 +1029,17 @@ public function testDiscussion10252(): void
 		$this->analyse([__DIR__ . '/data/discussion-10252.php'], []);
 	}
 
+	public function testBug10418(): void
+	{
+		if (PHP_VERSION_ID < 80100) {
+			$this->markTestSkipped('Test requires PHP 8.1.');
+		}
+
+		$this->cliArgumentsVariablesRegistered = true;
+		$this->polluteScopeWithLoopInitialAssignments = true;
+		$this->checkMaybeUndefinedVariables = true;
+		$this->polluteScopeWithAlwaysIterableForeach = true;
+		$this->analyse([__DIR__ . '/data/bug-10418.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Variables/data/bug-10418.php

@@ -0,0 +1,12 @@
+<?php declare(strict_types = 1);
+
+namespace Bug10418;
+
+function (): void {
+	$text = '123';
+	$result = match(1){
+		preg_match('/(\d+)/', $text, $match) => 'matched number: ' . $match[1],
+		preg_match('/(\w+)/', $text, $match) => 'matched word: ' . json_encode($match),
+		default => 'no matches!'
+	};
+};