instanceof -> is

fully handled by hhast now; manually fixed up a new error - we had
nonnull, but know it's an XHPChild

closes #197

Author: fredemmott

src/core/ComposableElement.php

@@ -46,7 +46,7 @@ final public function __construct(
     foreach ($attributes as $key => $value) {
       if (self::isSpreadKey($key)) {
         invariant(
-          $value instanceof :x:composable-element,
+          $value is :x:composable-element,
           "Only XHP can be used with an attribute spread operator",
         );
         $this->spreadElementImpl($value);
@@ -78,14 +78,14 @@ final public function __construct(
    * @param $child     single child or array of children
    */
   final public function appendChild(mixed $child): this {
-    if ($child instanceof Traversable) {
+    if ($child is Traversable<_>) {
       foreach ($child as $c) {
         $this->appendChild($c);
       }
-    } else if ($child instanceof :x:frag) {
+    } else if ($child is :x:frag) {
       $this->children->addAll($child->getChildren());
     } else if ($child !== null) {
-      assert($child instanceof XHPChild);
+      assert($child is XHPChild);
       $this->children->add($child);
     }
     return $this;
@@ -116,20 +116,20 @@ final public function replaceChildren(XHPChild ...$children): this {
     $new_children = Vector {};
     foreach ($children as $xhp) {
       /* HH_FIXME[4273] bogus "XHPChild always truthy" - FB T41388073 */
-    if ($xhp instanceof :x:frag) {
+    if ($xhp is :x:frag) {
       foreach ($xhp->children as $child) {
         $new_children->add($child);
       }
-    } else if (!($xhp instanceof Traversable)) {
+    } else if (!($xhp is Traversable<_>)) {
       $new_children->add($xhp);
     } else {
       foreach ($xhp as $element) {
-        if ($element instanceof :x:frag) {
+        if ($element is :x:frag) {
           foreach ($element->children as $child) {
             $new_children->add($child);
           }
         } else if ($element !== null) {
-          $new_children->add($element);
+          $new_children->add($element as XHPChild);
         }
       }
     }
@@ -153,7 +153,7 @@ final public function getChildren(
       if ($selector[0] == '%') {
         $selector = substr($selector, 1);
         foreach ($this->children as $child) {
-          if ($child instanceof :xhp && $child->categoryOf($selector)) {
+          if ($child is :xhp && $child->categoryOf($selector)) {
             $children->add($child);
           }
         }
@@ -186,7 +186,7 @@ final public function getFirstChild(?string $selector = null): ?XHPChild {
     } else if ($selector[0] == '%') {
       $selector = substr($selector, 1);
       foreach ($this->children as $child) {
-        if ($child instanceof :xhp && $child->categoryOf($selector)) {
+        if ($child is :xhp && $child->categoryOf($selector)) {
           return $child;
         }
       }
@@ -735,7 +735,7 @@ final private function validateChildrenRule(
       case XHPChildrenConstraintType::PCDATA:
         if (
           $this->children->containsKey($index) &&
-          !($this->children->get($index) instanceof :xhp)
+          !($this->children->get($index) is :xhp)
         ) {
           return tuple(true, $index + 1);
         }
@@ -754,13 +754,13 @@ final private function validateChildrenRule(
       case XHPChildrenConstraintType::CATEGORY:
         if (
           !$this->children->containsKey($index) ||
-          !($this->children->get($index) instanceof :xhp)
+          !($this->children->get($index) is :xhp)
         ) {
           return tuple(false, $index);
         }
         $category = :xhp::class2element($expr->getConstraintString());
         $child = $this->children->get($index);
-        assert($child instanceof :xhp);
+        assert($child is :xhp);
         $categories = $child->__xhpCategoryDeclaration();
         if (($categories[$category] ?? 0) === 0) {
           return tuple(false, $index);
@@ -795,7 +795,7 @@ public function __getChildrenDeclaration(): string {
   final public function __getChildrenDescription(): string {
     $desc = array();
     foreach ($this->children as $child) {
-      if ($child instanceof :xhp) {
+      if ($child is :xhp) {
         $tmp = ':'.:xhp::class2element(get_class($child));
         $categories = $child->__xhpCategoryDeclaration();
         if (C\count($categories) > 0) {

src/core/Element.php

@@ -45,7 +45,7 @@ final public function toString(): string {
     }
 
     $composed->__transferContext($this->getAllContexts());
-    if ($this instanceof XHPHasTransferAttributes) {
+    if ($this is XHPHasTransferAttributes) {
       $this->transferAttributesToRenderedRoot($composed);
     }
 
@@ -56,11 +56,11 @@ final public function toString(): string {
   ): Awaitable<:x:primitive> {
     $that = $this;
     // Flush root elements returned from render() to an :x:primitive
-    while ($that instanceof :x:element) {
+    while ($that is :x:element) {
       $that = await $that->__renderAndProcess();
     }
 
-    if ($that instanceof :x:primitive) {
+    if ($that is :x:primitive) {
       return $that;
     }
 

src/core/Primitive.php

@@ -30,7 +30,7 @@ final public function toString(): string {
     $children = $this->getChildren();
     $awaitables = Map {};
     foreach ($children as $idx => $child) {
-      if ($child instanceof :x:composable-element) {
+      if ($child is :x:composable-element) {
         $child->__transferContext($this->getAllContexts());
         $awaitables[$idx] = $child->__flushSubtree();
       }

src/core/XHP.php

@@ -89,13 +89,13 @@ final public function jsonSerialize(): string {
   }
 
   final protected static function renderChild(XHPChild $child): string {
-    if ($child instanceof :xhp) {
+    if ($child is :xhp) {
       return $child->toString();
     }
-    if ($child instanceof XHPUnsafeRenderable) {
+    if ($child is XHPUnsafeRenderable) {
       return $child->toHTMLString();
     }
-    if ($child instanceof Traversable) {
+    if ($child is Traversable<_>) {
       throw new XHPRenderArrayException('Can not render traversables!');
     }
 

src/core/XHPAttributeCoercion.php

@@ -65,7 +65,7 @@ public static function CoerceToString(
     mixed $val,
   ): string {
     self::LogCoercion($context, 'string', $attr, $val);
-    if (($val is int) || ($val is float) || $val instanceof Stringish) {
+    if (($val is int) || ($val is float) || $val is Stringish) {
       return (string)$val;
     }
 

src/html/Element.php

@@ -118,7 +118,7 @@ protected final function renderBaseAttrs(): string {
         if ($val === true) {
           $buf .= ' '.htmlspecialchars($key);
         } else {
-          if ($val instanceof XHPUnsafeAttributeValue) {
+          if ($val is XHPUnsafeAttributeValue) {
             $val_str = $val->toHTMLString();
           } else {
             $val_str = htmlspecialchars((string) $val, ENT_COMPAT);

src/html/XHPHelpers.php

@@ -145,8 +145,8 @@ protected function getAttributeNamesThatAppendValuesOnTransfer(
   final public function transferAttributesToRenderedRoot(
     :x:composable-element $root,
   ): void {
-    if (:xhp::isAttributeValidationEnabled() && $root instanceof :x:element) {
-      if (!($root instanceof HasXHPHelpers)) {
+    if (:xhp::isAttributeValidationEnabled() && $root is :x:element) {
+      if (!($root is HasXHPHelpers)) {
         throw new XHPClassException(
           $this,
           'render() must return an object using the XHPHelpers trait.',