Converge loops nested in a top-level loop's convergence passes instead of walking them once

src/Analyser/StatementContext.php

@@ -23,6 +23,7 @@ private function __construct(
 		private bool $resolveTemplateArguments = true,
 		private ?Type $expectedReturnType = null,
 		private ?Type $nativeExpectedReturnType = null,
+		private bool $convergesLoops = false,
 	)
 	{
 	}
@@ -48,6 +49,35 @@ public function isTopLevel(): bool
 		return $this->isTopLevel;
 	}
 
+	/**
+	 * Whether loops walk their body until the types stabilize. Besides the
+	 * top level, the loops nested in a convergence pass of a top-level loop
+	 * do, and so do the loops nested in their final walks - otherwise a
+	 * variable a nested loop changes over several iterations keeps the type
+	 * of its first iteration in the outer loop's passes.
+	 */
+	public function shouldConvergeLoops(): bool
+	{
+		return $this->isTopLevel || $this->convergesLoops;
+	}
+
+	/**
+	 * The context of a loop's convergence pass. The loops nested in a pass of
+	 * a top-level loop converge themselves, their passes' nested loops are
+	 * walked once.
+	 */
+	public function enterLoopPass(): self
+	{
+		if ($this->isTopLevel) {
+			return new self(false, $this->foreachUnrollFactor, $this->resolveTemplateArguments, $this->expectedReturnType, $this->nativeExpectedReturnType, true);
+		}
+		if ($this->convergesLoops) {
+			return new self(false, $this->foreachUnrollFactor, $this->resolveTemplateArguments, $this->expectedReturnType, $this->nativeExpectedReturnType);
+		}
+
+		return $this;
+	}
+
 	public function getForeachUnrollFactor(): int
 	{
 		return $this->foreachUnrollFactor;
@@ -64,7 +94,7 @@ public function withoutTemplateArgumentResolution(): self
 			return $this;
 		}
 
-		return new self($this->isTopLevel, $this->foreachUnrollFactor, false, $this->expectedReturnType, $this->nativeExpectedReturnType);
+		return new self($this->isTopLevel, $this->foreachUnrollFactor, false, $this->expectedReturnType, $this->nativeExpectedReturnType, $this->convergesLoops);
 	}
 
 	/**
@@ -78,7 +108,7 @@ public function withExpectedReturnType(?Type $expectedReturnType, ?Type $nativeE
 			return $this;
 		}
 
-		return new self($this->isTopLevel, $this->foreachUnrollFactor, $this->resolveTemplateArguments, $expectedReturnType, $nativeExpectedReturnType);
+		return new self($this->isTopLevel, $this->foreachUnrollFactor, $this->resolveTemplateArguments, $expectedReturnType, $nativeExpectedReturnType, $this->convergesLoops);
 	}
 
 	public function getExpectedReturnType(): ?Type
@@ -102,7 +132,7 @@ public function enterDeep(): self
 
 	public function enterUnrolledForeach(int $totalKeys): self
 	{
-		return new self($this->isTopLevel, $this->foreachUnrollFactor * $totalKeys, $this->resolveTemplateArguments, $this->expectedReturnType, $this->nativeExpectedReturnType);
+		return new self($this->isTopLevel, $this->foreachUnrollFactor * $totalKeys, $this->resolveTemplateArguments, $this->expectedReturnType, $this->nativeExpectedReturnType, $this->convergesLoops);
 	}
 
 }

src/Analyser/StmtHandler/DoWhileHandler.php

@@ -67,7 +67,7 @@ public function processStmt(
 		$prevEntryScope = null;
 		$previousPass = null;
 		$previousPassStorage = null;
-		if ($context->isTopLevel()) {
+		if ($context->shouldConvergeLoops()) {
 			$bodyIsReplayable = $nodeScopeResolver->isReplayableConvergenceBody($stmt, $stmt->stmts);
 			// each pass after the first re-walks only the statements whose
 			// entry state differs from the previous pass's (StatementsHandler::processLoopPassStmtNodes())
@@ -91,7 +91,7 @@ public function processStmt(
 				$scope->pushExpressionResultStorage($storage);
 				try {
 					$passRecord = null;
-					$bodyScopeResult = $nodeScopeResolver->processLoopPassStmtNodes($stmt, $stmt->stmts, $bodyScope, $storage, $bodyRecording, $context->enterDeep()->withoutTemplateArgumentResolution(), $previousPass, $passRecord)->filterOutLoopExitPoints();
+					$bodyScopeResult = $nodeScopeResolver->processLoopPassStmtNodes($stmt, $stmt->stmts, $bodyScope, $storage, $bodyRecording, $context->enterLoopPass()->withoutTemplateArgumentResolution(), $previousPass, $passRecord)->filterOutLoopExitPoints();
 					$previousPass = $passRecord;
 					$previousPassStorage = $storage;
 					$backEdgeScope = $bodyScopeResult->getLoopBackEdgeScope();

src/Analyser/StmtHandler/ForHandler.php

@@ -195,7 +195,7 @@ public function processStmt(
 			}
 		}
 
-		if ($context->isTopLevel()) {
+		if ($context->shouldConvergeLoops()) {
 			$count = 0;
 			$prevEntryScope = null;
 			// each pass after the first re-walks only the statements whose
@@ -226,7 +226,7 @@ public function processStmt(
 						$passFlows[] = $passCondResult->getVariableFlow();
 					}
 					$passRecord = null;
-					$bodyScopeResult = $nodeScopeResolver->processLoopPassStmtNodes($stmt, $stmt->stmts, $bodyScope, $storage, new NoopNodeCallback(), $context->enterDeep()->withoutTemplateArgumentResolution(), $previousPass, $passRecord)->filterOutLoopExitPoints();
+					$bodyScopeResult = $nodeScopeResolver->processLoopPassStmtNodes($stmt, $stmt->stmts, $bodyScope, $storage, new NoopNodeCallback(), $context->enterLoopPass()->withoutTemplateArgumentResolution(), $previousPass, $passRecord)->filterOutLoopExitPoints();
 					$previousPass = $passRecord;
 					$previousPassStorage = $storage;
 					$passFlows[] = $bodyScopeResult->getVariableFlow();

src/Analyser/StmtHandler/ForeachHandler.php

@@ -195,7 +195,7 @@ static function () use ($condResult, $emptyArrayType): Type {
 		$replayEntryScope = null;
 		$unrolledEndScope = null;
 		$unrolledTotalKeys = null;
-		if ($context->isTopLevel()) {
+		if ($context->shouldConvergeLoops()) {
 			$storage = $originalStorage->duplicate();
 
 			$originalScope = $nonEmptyIterateeScope;
@@ -213,7 +213,7 @@ static function () use ($condResult, $emptyArrayType): Type {
 				$foreachIterateeType = $iterateeResult->getType();
 				$foreachNativeIterateeType = $iterateeResult->getNativeType();
 			}
-			$unrolledResult = $this->tryProcessUnrolledConstantArrayForeach($nodeScopeResolver, $stmt, $originalScope, $originalStorage, $context, $foreachIterateeType, $foreachNativeIterateeType);
+			$unrolledResult = $context->isTopLevel() ? $this->tryProcessUnrolledConstantArrayForeach($nodeScopeResolver, $stmt, $originalScope, $originalStorage, $context, $foreachIterateeType, $foreachNativeIterateeType) : null;
 			if ($unrolledResult !== null) {
 				$bodyScope = $unrolledResult['bodyScope'];
 				$unrolledEndScope = $unrolledResult['endScope'];
@@ -250,7 +250,7 @@ static function () use ($condResult, $emptyArrayType): Type {
 					try {
 						$bodyScope = $this->enterForeach($nodeScopeResolver, $bodyScope, $storage, $originalScope, $stmt, $foreachIterateeType, $foreachNativeIterateeType, $nodeCallback);
 						$passRecord = null;
-						$bodyScopeResult = $nodeScopeResolver->processLoopPassStmtNodes($stmt, $stmt->stmts, $bodyScope, $storage, $bodyRecording, $context->enterDeep()->withoutTemplateArgumentResolution(), $previousPass, $passRecord)->filterOutLoopExitPoints();
+						$bodyScopeResult = $nodeScopeResolver->processLoopPassStmtNodes($stmt, $stmt->stmts, $bodyScope, $storage, $bodyRecording, $context->enterLoopPass()->withoutTemplateArgumentResolution(), $previousPass, $passRecord)->filterOutLoopExitPoints();
 						$previousPass = $passRecord;
 						$previousPassStorage = $storage;
 						$backEdgeScope = $bodyScopeResult->getLoopBackEdgeScope();

src/Analyser/StmtHandler/WhileHandler.php

@@ -94,7 +94,7 @@ public function processStmt(
 		$prevEntryScope = null;
 		$previousPass = null;
 		$previousPassStorage = null;
-		if ($context->isTopLevel()) {
+		if ($context->shouldConvergeLoops()) {
 			$count = 0;
 			$bodyIsReplayable = $nodeScopeResolver->isReplayableConvergenceBody($stmt, $stmt->stmts);
 			do {
@@ -119,7 +119,7 @@ public function processStmt(
 					$passCondResult = $nodeScopeResolver->processExprNode($stmt, $stmt->cond, $bodyScope, $storage, $condRecording, ExpressionContext::createDeep(resolveTemplateArguments: false));
 					$bodyScope = $passCondResult->getTruthyScope();
 					$passRecord = null;
-					$bodyScopeResult = $nodeScopeResolver->processLoopPassStmtNodes($stmt, $stmt->stmts, $bodyScope, $storage, $bodyRecording, $context->enterDeep()->withoutTemplateArgumentResolution(), $previousPass, $passRecord)->filterOutLoopExitPoints();
+					$bodyScopeResult = $nodeScopeResolver->processLoopPassStmtNodes($stmt, $stmt->stmts, $bodyScope, $storage, $bodyRecording, $context->enterLoopPass()->withoutTemplateArgumentResolution(), $previousPass, $passRecord)->filterOutLoopExitPoints();
 					$previousPass = $passRecord;
 					$previousPassStorage = $storage;
 					$backEdgeScope = $bodyScopeResult->getLoopBackEdgeScope();

tests/PHPStan/Analyser/nsrt/bug-10438.php

@@ -21,7 +21,7 @@ public function extract(SimpleXMLElement $data, string $type = 'Meta'): array
 				$meta[$key] = (string)$tag->{$valueName};
 				continue;
 			}
-			assertType('array<string, array{}|array{string}|string>', $meta);
+			assertType('array<string, list<string>|string>', $meta);
 			$meta[$key] = [];
 			assertType('array{}', $meta[$key]);
 			foreach ($tag->{$valueName} as $value) {

tests/PHPStan/Analyser/nsrt/bug-10666.php

@@ -0,0 +1,26 @@
+<?php declare(strict_types = 1);
+
+namespace Bug10666;
+
+use function PHPStan\Testing\assertType;
+
+class Foo
+{
+	public function text(int $maxNbChars = 200): string
+	{
+		$text = [];
+		while (empty($text)) {
+			$size = 0;
+			while ($size < $maxNbChars) {
+				$text[] = 'x';
+				$size++;
+			}
+
+			assertType("list<'x'>", $text);
+			array_pop($text);
+			assertType("list<'x'>", $text);
+		}
+
+		return implode('', $text);
+	}
+}

tests/PHPStan/Analyser/nsrt/bug-14935.php

@@ -0,0 +1,29 @@
+<?php declare(strict_types = 1);
+
+namespace Bug14935;
+
+use function PHPStan\Testing\assertType;
+
+/**
+ * @param list<list<float>> $groups
+ */
+function countRejected(array $groups): int
+{
+	$rejected = 0;
+
+	foreach ($groups as $readings) {
+		$copy = [];
+		foreach ($readings as $reading) {
+			$copy[] = $reading;
+		}
+		assertType('list<float>', $copy);
+
+		if (count($copy) > 1) {
+			$rejected++;
+		}
+	}
+
+	assertType('int<0, max>', $rejected);
+
+	return $rejected;
+}

tests/PHPStan/Analyser/nsrt/bug-15420.php

@@ -0,0 +1,29 @@
+<?php declare(strict_types = 1);
+
+namespace Bug15420;
+
+use function PHPStan\Testing\assertType;
+
+class Test {
+	/** @param string[] $cards */
+	public function f(array $cards): void
+	{
+	    for ($i = 0; $i < 10; $i++) {
+	        $seen = [];
+	        $later = [];
+	        foreach ($cards as $card) {
+	            if (array_key_exists($card, $seen)) {
+	                $later[] = $card;
+	                continue;
+	            }
+	            $seen[$card] = true;
+	        }
+	        assertType('int<0, 9>', $i);
+	        if ($later !== []) {
+	            $cards = $later;
+	        } else {
+	            break;
+	        }
+	    }
+	}
+}