Suppress always-true loop warnings when loop body contains yield

- Generator suspension points (yield/yield from) act as break points,
  so while(true) { yield $x; } is valid and not a true infinite loop
- Added hasYield flag to BreaklessWhileLoopNode and DoWhileLoopConditionNode
- WhileLoopAlwaysTrueConditionRule and DoWhileLoopConstantConditionRule
  now skip the warning when the loop body contains a yield
- Loops without yield in a generator still correctly report the warning

Closes phpstan/phpstan#6189

Author: phpstan-bot

src/Analyser/NodeScopeResolver.php

@@ -1525,7 +1525,7 @@ private function processStmtNode(
 			}
 
 			$isIterableAtLeastOnce = $beforeCondBooleanType->isTrue()->yes();
-			$this->callNodeCallback($nodeCallback, new BreaklessWhileLoopNode($stmt, $finalScopeResult->toPublic()->getExitPoints()), $bodyScopeMaybeRan, $storage);
+			$this->callNodeCallback($nodeCallback, new BreaklessWhileLoopNode($stmt, $finalScopeResult->toPublic()->getExitPoints(), $finalScopeResult->hasYield()), $bodyScopeMaybeRan, $storage);
 
 			if ($alwaysIterates) {
 				$isAlwaysTerminating = count($finalScopeResult->getExitPointsByType(Break_::class)) === 0;
@@ -1607,7 +1607,7 @@ private function processStmtNode(
 				$alwaysIterates = $condBooleanType->isTrue()->yes();
 			}
 
-			$this->callNodeCallback($nodeCallback, new DoWhileLoopConditionNode($stmt->cond, $bodyScopeResult->toPublic()->getExitPoints()), $bodyScope, $storage);
+			$this->callNodeCallback($nodeCallback, new DoWhileLoopConditionNode($stmt->cond, $bodyScopeResult->toPublic()->getExitPoints(), $bodyScopeResult->hasYield()), $bodyScope, $storage);
 
 			if ($alwaysIterates) {
 				$alwaysTerminating = count($bodyScopeResult->getExitPointsByType(Break_::class)) === 0;

src/Node/BreaklessWhileLoopNode.php

@@ -16,7 +16,7 @@ final class BreaklessWhileLoopNode extends NodeAbstract implements VirtualNode
 	/**
 	 * @param StatementExitPoint[] $exitPoints
 	 */
-	public function __construct(private While_ $originalNode, private array $exitPoints)
+	public function __construct(private While_ $originalNode, private array $exitPoints, private bool $hasYield = false)
 	{
 		parent::__construct($originalNode->getAttributes());
 	}
@@ -34,6 +34,11 @@ public function getExitPoints(): array
 		return $this->exitPoints;
 	}
 
+	public function hasYield(): bool
+	{
+		return $this->hasYield;
+	}
+
 	#[Override]
 	public function getType(): string
 	{

src/Node/DoWhileLoopConditionNode.php

@@ -13,7 +13,7 @@ final class DoWhileLoopConditionNode extends NodeAbstract implements VirtualNode
 	/**
 	 * @param StatementExitPoint[] $exitPoints
 	 */
-	public function __construct(private Expr $cond, private array $exitPoints)
+	public function __construct(private Expr $cond, private array $exitPoints, private bool $hasYield = false)
 	{
 		parent::__construct($cond->getAttributes());
 	}
@@ -31,6 +31,11 @@ public function getExitPoints(): array
 		return $this->exitPoints;
 	}
 
+	public function hasYield(): bool
+	{
+		return $this->hasYield;
+	}
+
 	#[Override]
 	public function getType(): string
 	{

src/Rules/Comparison/DoWhileLoopConstantConditionRule.php

@@ -42,6 +42,9 @@ public function processNode(Node $node, Scope $scope): array
 		$exprType = $this->helper->getBooleanType($scope, $node->getCond());
 		if ($exprType instanceof ConstantBooleanType) {
 			if ($exprType->getValue()) {
+				if ($node->hasYield()) {
+					return [];
+				}
 				foreach ($node->getExitPoints() as $exitPoint) {
 					$statement = $exitPoint->getStatement();
 					if (!$statement instanceof Continue_) {

src/Rules/Comparison/WhileLoopAlwaysTrueConditionRule.php

@@ -68,6 +68,10 @@ public function processNode(
 		$originalNode = $node->getOriginalNode();
 		$exprType = $this->helper->getBooleanType($scope, $originalNode->cond);
 		if ($exprType->isTrue()->yes()) {
+			if ($node->hasYield()) {
+				return [];
+			}
+
 			$ref = $scope->getFunction() ?? $scope->getAnonymousFunctionReflection();
 
 			if ($ref !== null && $ref->getReturnType() instanceof NeverType) {

tests/PHPStan/Rules/Comparison/DoWhileLoopConstantConditionRuleTest.php

@@ -28,6 +28,11 @@ protected function getRule(): Rule
 		);
 	}
 
+	public function testBug6189(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-6189.php'], []);
+	}
+
 	public function testRule(): void
 	{
 		$this->analyse([__DIR__ . '/data/do-while-loop.php'], [

tests/PHPStan/Rules/Comparison/WhileLoopAlwaysTrueConditionRuleTest.php

@@ -54,4 +54,18 @@ public function testRulePHP81(): void
 		$this->analyse([__DIR__ . '/data/while-loop-true-php81.php'], []);
 	}
 
+	public function testBug6189(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-6189.php'], [
+			[
+				'While loop condition is always true.',
+				33,
+			],
+			[
+				'While loop condition is always true.',
+				44,
+			],
+		]);
+	}
+
 }

tests/PHPStan/Rules/Comparison/data/bug-6189.php

@@ -0,0 +1,59 @@
+<?php declare(strict_types = 1);
+
+namespace Bug6189;
+
+use Generator;
+
+class Foo
+{
+
+	/**
+	 * @return Generator<int, int, null, void>
+	 */
+	public function generatorWithYield(): Generator
+	{
+		while (true) {
+			yield 1;
+		}
+	}
+
+	/**
+	 * @return Generator<int, int, null, void>
+	 */
+	public function generatorWithYieldFrom(): Generator
+	{
+		while (true) {
+			yield from [1, 2, 3];
+		}
+	}
+
+	/** Still an infinite loop - no yield inside the while body */
+	public function noYieldInLoop(): void
+	{
+		while (true) {
+
+		}
+	}
+
+	/**
+	 * @return Generator<int, int, null, void>
+	 */
+	public function generatorWithYieldOutsideLoop(): Generator
+	{
+		yield 0;
+		while (true) {
+			// yield is outside the loop, so this is still an infinite loop
+		}
+	}
+
+	/**
+	 * @return Generator<int, int, null, void>
+	 */
+	public function generatorDoWhileWithYield(): Generator
+	{
+		do {
+			yield 1;
+		} while (true);
+	}
+
+}