Fix phpstan/phpstan#14353: Falsy "Variable might not be defined" after foreach

- After a foreach that conditionally defines a variable, conditional expressions
  are created tracking "if array is empty, variable doesn't exist"
- When isset() confirms the variable exists, specifyExpressionType sets certainty
  to Yes but stale conditional expressions with No certainty persist
- A subsequent foreach over the same array triggers filterByTruthyValue for the
  "array is empty" case, activating the stale conditional and removing the variable
- Fix: in specifyExpressionType, when certainty is Yes, remove conditional
  expressions for the variable that have No certainty (would unset it)
- New regression test in tests/PHPStan/Rules/Variables/data/bug-14353.php

Author: phpstan-bot

src/Analyser/MutatingScope.php

@@ -2758,14 +2758,25 @@ public function specifyExpressionType(Expr $expr, Type $type, Type $nativeType,
 		$nativeTypes = $scope->nativeExpressionTypes;
 		$nativeTypes[$exprString] = new ExpressionTypeHolder($expr, $nativeType, $certainty);
 
+		$conditionalExpressions = $this->conditionalExpressions;
+		if ($certainty->yes() && array_key_exists($exprString, $conditionalExpressions)) {
+			$conditionalExpressions[$exprString] = array_filter(
+				$conditionalExpressions[$exprString],
+				static fn (ConditionalExpressionHolder $holder) => !$holder->getTypeHolder()->getCertainty()->no(),
+			);
+			if ($conditionalExpressions[$exprString] === []) {
+				unset($conditionalExpressions[$exprString]);
+			}
+		}
+
 		$scope = $this->scopeFactory->create(
 			$this->context,
 			$this->isDeclareStrictTypes(),
 			$this->getFunction(),
 			$this->getNamespace(),
 			$expressionTypes,
 			$nativeTypes,
-			$this->conditionalExpressions,
+			$conditionalExpressions,
 			$this->inClosureBindScopeClasses,
 			$this->anonymousFunctionReflection,
 			$this->inFirstLevelStatement,

tests/PHPStan/Rules/Variables/DefinedVariableRuleTest.php

@@ -1514,4 +1514,13 @@ public function testBug14117(): void
 		]);
 	}
 
+	public function testBug14353(): void
+	{
+		$this->cliArgumentsVariablesRegistered = true;
+		$this->polluteScopeWithLoopInitialAssignments = false;
+		$this->checkMaybeUndefinedVariables = true;
+		$this->polluteScopeWithAlwaysIterableForeach = true;
+		$this->analyse([__DIR__ . '/data/bug-14353.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Variables/data/bug-14353.php

@@ -0,0 +1,42 @@
+<?php
+
+namespace Bug14353;
+
+/** @return array<int> */
+function get(): array
+{
+	return [1];
+}
+
+class Test
+{
+	/** @var mixed */
+	public $data;
+
+	public function test(): void
+	{
+		$reports = [];
+
+		foreach (get() as $report) {
+			$reports[$report] = $report;
+		}
+
+		if (isset($this->data)) {
+			foreach ($reports as $report_id => $report) {
+				$report_ids[$report_id] = 1;
+			}
+		} else {
+			foreach ($reports as $report_id => $report) {
+				$report_ids[$report_id] = 1;
+			}
+		}
+
+		if (isset($report_ids)) {
+			var_dump($report_ids);
+
+			foreach ($reports as $report) {}
+
+			var_dump($report_ids);
+		}
+	}
+}