Fix phpstan/phpstan#14117: Variable might not be defined false positive with same condition

- Fixed createConditionalExpressions in MutatingScope to preserve variables in
  newVariableTypes when their type matches but certainty differs between branches
- This ensures conditional expressions are created to track that a variable is
  definitely defined when the same condition holds as when it was assigned
- Removed now-unnecessary @phpstan-ignore variable.undefined comments in
  OptimizedDirectorySourceLocator.php that were working around this bug
- New regression test in tests/PHPStan/Rules/Variables/data/bug-14117.php

Author: phpstan-bot

src/Analyser/MutatingScope.php

@@ -4094,6 +4094,14 @@ private function createConditionalExpressions(
 				continue;
 			}
 
+			if (
+				array_key_exists($exprString, $newVariableTypes)
+				&& $newVariableTypes[$exprString]->equalTypes($holder)
+				&& !$newVariableTypes[$exprString]->getCertainty()->equals($holder->getCertainty())
+			) {
+				continue;
+			}
+
 			unset($newVariableTypes[$exprString]);
 		}
 

src/Reflection/BetterReflection/SourceLocator/OptimizedDirectorySourceLocator.php

@@ -127,7 +127,7 @@ public function locateIdentifier(Reflector $reflector, Identifier $identifier):
 				return null;
 			}
 
-			[$reflectionCacheKey, $variableCacheKey] = $this->getCacheKeys($file, $identifier); // @phpstan-ignore variable.undefined
+			[$reflectionCacheKey, $variableCacheKey] = $this->getCacheKeys($file, $identifier);
 			$classReflection = $this->nodeToReflection($reflector, $fetchedClassNode);
 			$this->cache->save($reflectionCacheKey, $variableCacheKey, $classReflection->exportToCache());
 
@@ -171,7 +171,7 @@ public function locateIdentifier(Reflector $reflector, Identifier $identifier):
 				return null;
 			}
 
-			[$reflectionCacheKey, $variableCacheKey] = $this->getCacheKeys($file, $identifier); // @phpstan-ignore variable.undefined
+			[$reflectionCacheKey, $variableCacheKey] = $this->getCacheKeys($file, $identifier);
 			$constantReflection = $this->nodeToReflection(
 				$reflector,
 				$fetchedConstantNode,

tests/PHPStan/Rules/Variables/DefinedVariableRuleTest.php

@@ -1333,4 +1333,23 @@ public function testBug5477(): void
 		$this->analyse([__DIR__ . '/data/bug-5477.php'], []);
 	}
 
+	public function testBug14117(): void
+	{
+		$this->cliArgumentsVariablesRegistered = true;
+		$this->polluteScopeWithLoopInitialAssignments = false;
+		$this->checkMaybeUndefinedVariables = true;
+		$this->polluteScopeWithAlwaysIterableForeach = true;
+
+		$this->analyse([__DIR__ . '/data/bug-14117.php'], [
+			[
+				'Variable $value might not be defined.',
+				33,
+			],
+			[
+				'Variable $value might not be defined.',
+				49,
+			],
+		]);
+	}
+
 }

tests/PHPStan/Rules/Variables/data/bug-14117.php

@@ -0,0 +1,51 @@
+<?php declare(strict_types = 1);
+
+namespace Bug14117;
+
+function foo(): void {
+	$key = rand(0, 2);
+
+	if ($key === 2) {
+		$value = 'test';
+	}
+
+	if ($key === 1) {
+		$value = 'test';
+	}
+
+	if ($key === 1) {
+		echo $value;
+	}
+}
+
+function bar(): void {
+	$key = rand(0, 2);
+
+	if ($key === 2) {
+		$value = 'two';
+	}
+
+	if ($key === 1) {
+		$value = 'one';
+	}
+
+	if ($key === 2) {
+		echo $value;
+	}
+}
+
+function baz(): void {
+	$key = rand(0, 3);
+
+	if ($key === 1) {
+		$value = 'one';
+	}
+
+	if ($key === 2) {
+		$value = 'two';
+	}
+
+	if ($key === 3) {
+		echo $value; // this one SHOULD report "might not be defined" because $key === 3 doesn't guarantee either earlier block ran
+	}
+}