Move intertwined ref preservation from assignVariable to invalidateExpression

Instead of preserving and restoring non-variable-to-variable intertwined refs
in assignVariable, handle them in invalidateExpression by skipping refs whose
endpoint variables (variableName, root of expr, root of assignedExpr) match
the variable being invalidated. Refs are still invalidated when a non-endpoint
variable (e.g. a dim index like $k in $a[$k]) changes.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: phpstan-bot

src/Analyser/MutatingScope.php

@@ -2573,29 +2573,6 @@ public function isUndefinedExpressionAllowed(Expr $expr): bool
 	public function assignVariable(string $variableName, Type $type, Type $nativeType, TrinaryLogic $certainty, array $intertwinedPropagatedFrom = []): self
 	{
 		$node = new Variable($variableName);
-
-		// Collect non-variable-to-variable intertwined refs for this variable before invalidation,
-		// as they may be lost during assignExpression and recursive propagation
-		$preservedIntertwinedRefs = [];
-		$preservedNativeIntertwinedRefs = [];
-		foreach ($this->expressionTypes as $exprString => $exprTypeHolder) {
-			$exprExpr = $exprTypeHolder->getExpr();
-			if (
-				!($exprExpr instanceof IntertwinedVariableByReferenceWithExpr)
-				|| $exprExpr->getVariableName() !== $variableName
-				|| $exprExpr->isVariableToVariableReference()
-			) {
-				continue;
-			}
-
-			$preservedIntertwinedRefs[$exprString] = $exprTypeHolder;
-			if (!array_key_exists($exprString, $this->nativeExpressionTypes)) {
-				continue;
-			}
-
-			$preservedNativeIntertwinedRefs[$exprString] = $this->nativeExpressionTypes[$exprString];
-		}
-
 		$scope = $this->assignExpression($node, $type, $nativeType);
 		if ($certainty->no()) {
 			throw new ShouldNotHappenException();
@@ -2653,33 +2630,6 @@ public function assignVariable(string $variableName, Type $type, Type $nativeTyp
 		foreach ($invalidatedIntertwinedRefs as $exprString) {
 			unset($scope->expressionTypes[$exprString]);
 			unset($scope->nativeExpressionTypes[$exprString]);
-			unset($preservedIntertwinedRefs[$exprString]);
-			unset($preservedNativeIntertwinedRefs[$exprString]);
-		}
-
-		// Re-add intertwined refs that were lost during propagation
-		foreach ($preservedIntertwinedRefs as $exprString => $exprTypeHolder) {
-			if (array_key_exists($exprString, $scope->expressionTypes)) {
-				continue;
-			}
-
-			$intertwinedExpr = $exprTypeHolder->getExpr();
-			if ($intertwinedExpr instanceof IntertwinedVariableByReferenceWithExpr) {
-				$assignedExpr = $intertwinedExpr->getAssignedExpr();
-				if ($assignedExpr instanceof Expr\ArrayDimFetch && $assignedExpr->var instanceof Expr\ArrayDimFetch && !$this->isNestedDimFetchPathValid($scope, $assignedExpr)) {
-					unset($preservedNativeIntertwinedRefs[$exprString]);
-					continue;
-				}
-			}
-
-			$scope->expressionTypes[$exprString] = $exprTypeHolder;
-		}
-		foreach ($preservedNativeIntertwinedRefs as $exprString => $exprTypeHolder) {
-			if (array_key_exists($exprString, $scope->nativeExpressionTypes)) {
-				continue;
-			}
-
-			$scope->nativeExpressionTypes[$exprString] = $exprTypeHolder;
 		}
 
 		return $scope;
@@ -2918,7 +2868,13 @@ public function invalidateExpression(Expr $expressionToInvalidate, bool $require
 			$exprExpr = $exprTypeHolder->getExpr();
 			if (
 				$exprExpr instanceof IntertwinedVariableByReferenceWithExpr
-				&& $exprExpr->isVariableToVariableReference()
+				&& $expressionToInvalidate instanceof Variable
+				&& is_string($expressionToInvalidate->name)
+				&& (
+					$exprExpr->getVariableName() === $expressionToInvalidate->name
+					|| $this->getIntertwinedRefRootVariableName($exprExpr->getExpr()) === $expressionToInvalidate->name
+					|| $this->getIntertwinedRefRootVariableName($exprExpr->getAssignedExpr()) === $expressionToInvalidate->name
+				)
 			) {
 				continue;
 			}
@@ -2989,6 +2945,17 @@ public function invalidateExpression(Expr $expressionToInvalidate, bool $require
 		);
 	}
 
+	private function getIntertwinedRefRootVariableName(Expr $expr): ?string
+	{
+		if ($expr instanceof Variable && is_string($expr->name)) {
+			return $expr->name;
+		}
+		if ($expr instanceof Expr\ArrayDimFetch) {
+			return $this->getIntertwinedRefRootVariableName($expr->var);
+		}
+		return null;
+	}
+
 	private function shouldInvalidateExpression(string $exprStringToInvalidate, Expr $exprToInvalidate, Expr $expr, string $exprString, bool $requireMoreCharacters = false, ?ClassReflection $invalidatingClass = null): bool
 	{
 		if ($requireMoreCharacters && $exprStringToInvalidate === $exprString) {

src/Node/Expr/IntertwinedVariableByReferenceWithExpr.php

@@ -4,9 +4,7 @@
 
 use Override;
 use PhpParser\Node\Expr;
-use PhpParser\Node\Expr\Variable;
 use PHPStan\Node\VirtualNode;
-use function is_string;
 
 final class IntertwinedVariableByReferenceWithExpr extends Expr implements VirtualNode
 {
@@ -31,14 +29,6 @@ public function getAssignedExpr(): Expr
 		return $this->assignedExpr;
 	}
 
-	public function isVariableToVariableReference(): bool
-	{
-		return $this->expr instanceof Variable
-			&& is_string($this->expr->name)
-			&& $this->assignedExpr instanceof Variable
-			&& is_string($this->assignedExpr->name);
-	}
-
 	#[Override]
 	public function getType(): string
 	{