Mark for/while loops as never exiting when every fall-through iteration keeps the condition satisfied

src/Analyser/NodeScopeResolver.php

@@ -1726,6 +1726,18 @@
 				$condBooleanType = ($this->treatPhpDocTypesAsCertain ? $bodyScopeMaybeRan->getType($stmt->cond) : $bodyScopeMaybeRan->getNativeType($stmt->cond))->toBoolean();
 				$alwaysIterates = $condBooleanType->isTrue()->yes();
 				$neverIterates = $condBooleanType->isFalse()->yes();
+
+				// When every non-terminating path through the body keeps the loop condition
+				// satisfied (e.g. the boundary iteration always returns or throws), the loop can
+				// never exit normally, so the code after it is unreachable.
+				if (
+					!$alwaysIterates
+					&& $beforeCondBooleanType->isTrue()->yes()
+					&& !$finalScopeResult->isAlwaysTerminating()
+					&& $finalScopeResult->getScope()->getType($stmt->cond)->toBoolean()->isTrue()->yes()
+				) {
+					$alwaysIterates = true;
+				}
 			}
 			if (!$alwaysIterates) {
 				foreach ($finalScopeResult->getExitPointsByType(Continue_::class) as $continueExitPoint) {
@@ -1957,6 +1969,20 @@
 			foreach ($stmt->loop as $loopExpr) {
 				$loopScope = $this->processExprNode($stmt, $loopExpr, $loopScope, $storage, $nodeCallback, ExpressionContext::createTopLevel())->getScope();
 			}
+
+			// When every non-terminating path through the body keeps the loop condition
+			// satisfied (e.g. the boundary iteration always returns or throws), the loop can
+			// never exit normally, so the code after it is unreachable.
+			if (
+				$context->isTopLevel()
+				&& $lastCondExpr !== null
+				&& $isIterableAtLeastOnce->yes()
+				&& !$finalScopeResult->isAlwaysTerminating()
+				&& $loopScope->getType($lastCondExpr)->toBoolean()->isTrue()->yes()
+			) {
+				$alwaysIterates = TrinaryLogic::createYes();
+			}
+
 			$finalScope = $finalScope->generalizeWith($loopScope);
 
 			if ($lastCondExpr !== null) {

tests/PHPStan/Rules/Missing/MissingReturnRuleTest.php

@@ -380,4 +380,11 @@ public function testBug14638(): void
 		$this->analyse([__DIR__ . '/data/bug-14638.php'], []);
 	}
 
+	#[RequiresPhp('>= 8.0')]
+	public function testBug9444(): void
+	{
+		$this->checkExplicitMixedMissingReturn = true;
+		$this->analyse([__DIR__ . '/data/bug-9444.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Missing/data/bug-9444.php

@@ -0,0 +1,72 @@
+<?php // lint >= 8.0
+
+declare(strict_types = 1);
+
+namespace Bug9444;
+
+class One
+{
+	private static int $i = 0;
+
+	public static function run(): string
+	{
+		self::$i++;
+		if (self::$i <= 3) {
+			throw new \Exception('One:run');
+		}
+
+		return 'Ok';
+	}
+}
+
+class Main
+{
+	public function process(): string
+	{
+		for ($i = 0; $i <= 5; $i++) {
+			try {
+				return One::run();
+			} catch (\Throwable $e) {
+				$sleep = match ($i) {
+					0 => 0.5,
+					1 => 1,
+					2 => 3,
+					3 => 6,
+					4 => 9,
+					default => throw $e,
+				};
+
+				echo $sleep . PHP_EOL;
+			}
+		}
+	}
+
+	public function processWithIf(): string
+	{
+		for ($i = 0; $i <= 5; $i++) {
+			try {
+				return One::run();
+			} catch (\Throwable $e) {
+				if ($i >= 5) {
+					throw $e;
+				}
+				echo $i . PHP_EOL;
+			}
+		}
+	}
+
+	public function processWhile(): string
+	{
+		$i = 0;
+		while ($i <= 5) {
+			try {
+				return One::run();
+			} catch (\Throwable $e) {
+				if ($i >= 5) {
+					throw $e;
+				}
+				$i++;
+			}
+		}
+	}
+}