Skip conditional expression guard when guard type is a subtype of the other branch's value

src/Analyser/MutatingScope.php

@@ -3861,9 +3861,11 @@ private function createConditionalExpressions(
 					&& $theirExpressionTypes[$guardExprString]->getCertainty()->yes()
 				) {
 					$guardIsSuperTypeOfTheirExpr = $guardHolder->getType()->isSuperTypeOf($theirExpressionTypes[$guardExprString]->getType());
+					$theirExprIsSuperTypeOfGuard = $theirExpressionTypes[$guardExprString]->getType()->isSuperTypeOf($guardHolder->getType());
 
 					if (
 						$guardIsSuperTypeOfTheirExpr->yes()
+						|| $theirExprIsSuperTypeOfGuard->yes()
 						|| (
 							array_key_exists($exprString, $theirExpressionTypes)
 							&& $theirExpressionTypes[$exprString]->getCertainty()->yes()

tests/PHPStan/Analyser/nsrt/bug-14807.php

@@ -0,0 +1,35 @@
+<?php // lint >= 8.1
+
+declare(strict_types = 1);
+
+namespace Bug14807;
+
+use function PHPStan\Testing\assertType;
+
+enum Color
+{
+	case Red;
+	case Blue;
+}
+
+class Item
+{
+	public bool $ready = false;
+}
+
+function process(Color $color, Item $item): void
+{
+	if ($color !== Color::Red && $item->ready === true) {
+		assertType('true', $item->ready);
+	}
+
+	// The narrowing from the first `if` must not leak here: reusing the same
+	// enum left-hand condition does not imply $item->ready is still true.
+	if ($color !== Color::Red) {
+		assertType('bool', $item->ready);
+	}
+
+	if ($color !== Color::Red && $item->ready === false) {
+		assertType('false', $item->ready);
+	}
+}

tests/PHPStan/Rules/Comparison/BooleanAndConstantConditionRuleTest.php

@@ -451,6 +451,12 @@ public function testBug8555(): void
 		$this->analyse([__DIR__ . '/data/bug-8555.php'], []);
 	}
 
+	public function testBug14807(): void
+	{
+		$this->treatPhpDocTypesAsCertain = true;
+		$this->analyse([__DIR__ . '/data/bug-14807.php'], []);
+	}
+
 	public function testInTrait(): void
 	{
 		$this->treatPhpDocTypesAsCertain = true;

tests/PHPStan/Rules/Comparison/data/bug-14807.php

@@ -0,0 +1,27 @@
+<?php // lint >= 8.1
+
+declare(strict_types = 1);
+
+namespace BugRule14807;
+
+enum Color
+{
+	case Red;
+	case Blue;
+}
+
+class Item
+{
+	public bool $ready = false;
+}
+
+function process(Color $color, Item $item): void
+{
+	if ($color !== Color::Red && $item->ready === true) {
+		echo 'go';
+	}
+
+	if ($color !== Color::Red && $item->ready === false) {
+		throw new \RuntimeException('stop');
+	}
+}