array_key_exist inference is lost when adding a false condition

Author: staabm

src/Analyser/TypeSpecifier.php

@@ -663,7 +663,17 @@ public function specifyTypesInCondition(
 			$leftTypes = $this->specifyTypesInCondition($scope, $expr->left, $context)->setRootExpr($expr);
 			$rightScope = $scope->filterByFalseyValue($expr->left);
 			$rightTypes = $this->specifyTypesInCondition($rightScope, $expr->right, $context)->setRootExpr($expr);
-			$types = $context->true() ? $leftTypes->normalize($scope)->intersectWith($rightTypes->normalize($rightScope)) : $leftTypes->unionWith($rightTypes);
+
+			if ($context->true()) {
+				if ($scope->getType($expr->left)->isFalse()->yes()) {
+					$types = $rightTypes->normalize($rightScope);
+				} else {
+					$types = $leftTypes->normalize($scope)->intersectWith($rightTypes->normalize($rightScope));
+				}
+			} else {
+				$types = $leftTypes->unionWith($rightTypes);
+			}
+
 			if ($context->true()) {
 				return (new SpecifiedTypes(
 					$types->getSureTypes(),

tests/PHPStan/Analyser/nsrt/bug-11276.php

@@ -0,0 +1,16 @@
+<?php
+
+use function PHPStan\Testing\assertType;
+
+function sayEqualArrayShape(int $i, $arr): void
+{
+	if (
+		false || array_key_exists($i, $arr)
+	) {
+		assertType('non-empty-array', $arr);
+	}
+
+	if (array_key_exists($i, $arr)) {
+		assertType('non-empty-array', $arr);
+	}
+}