Fix maybe-undefined variable regression in loops with unrelated assignments

- Fixed intersectConditionalExpressions to keep matching conditional expression
  keys instead of dropping all keys when any single key mismatches
- The previous all-or-nothing behavior caused conditional expressions (e.g. for
  variable certainty based on method return values) to be entirely dropped when
  an unrelated conditional expression key was added during loop scope merging
- New regression test in tests/PHPStan/Analyser/nsrt/bug-14269.php

Closes phpstan/phpstan#14269

Author: phpstan-bot

src/Analyser/MutatingScope.php

@@ -3431,13 +3431,19 @@ private function intersectConditionalExpressions(array $otherConditionalExpressi
 			}
 
 			$otherHolders = $otherConditionalExpressions[$exprString];
-			foreach (array_keys($holders) as $key) {
+			$intersectedHolders = [];
+			foreach ($holders as $key => $holder) {
 				if (!array_key_exists($key, $otherHolders)) {
-					continue 2;
+					continue;
 				}
+				$intersectedHolders[$key] = $holder;
+			}
+
+			if (count($intersectedHolders) === 0) {
+				continue;
 			}
 
-			$newConditionalExpressions[$exprString] = $holders;
+			$newConditionalExpressions[$exprString] = $intersectedHolders;
 		}
 
 		return $newConditionalExpressions;

tests/PHPStan/Analyser/nsrt/bug-14269.php

@@ -0,0 +1,60 @@
+<?php declare(strict_types = 1);
+
+namespace Bug14269;
+
+use PHPStan\TrinaryLogic;
+use function PHPStan\Testing\assertVariableCertainty;
+
+class Package
+{
+
+	public function isMultiDay(): bool
+	{
+		return true;
+	}
+
+	/**
+	 * @return string[]
+	 */
+	public function getWorkspaces(): array
+	{
+		return [];
+	}
+
+	/**
+	 * @return int[]|null
+	 */
+	public function getService(): ?array
+	{
+		return [];
+	}
+
+}
+
+class ReturnsSelf
+{
+
+	public function subtract(): self
+	{
+		return $this;
+	}
+
+}
+
+function doFoo(Package $package, ReturnsSelf $s): void {
+	if (!$package->isMultiDay()) {
+		$packageDurationInMinutes = 60;
+	}
+
+	foreach ($package->getWorkspaces() as $workplace) {
+		$availableIntervals = $s->subtract();
+		if ($package->getService() !== null && !$package->isMultiDay()) {
+			assertVariableCertainty(TrinaryLogic::createYes(), $packageDurationInMinutes);
+			continue;
+		}
+
+		$availableIntervals = $package->isMultiDay()
+			? 'aaa'
+			: 'bbb';
+	}
+}