Support clone(...) first-class callable syntax

Author: thekid

src/main/php/lang/ast/emit/CallablesAsClosures.class.php

@@ -48,8 +48,12 @@ private function emitQuoted($result, $node) {
   }
 
   protected function emitCallable($result, $callable) {
-    $result->out->write('\Closure::fromCallable(');
-    $this->emitQuoted($result, $callable->expression);
-    $result->out->write(')');
+    if ($callable->expression instanceof Literal && 'clone' === $callable->expression->expression) {
+      $result->out->write('fn($o) => clone $o');
+    } else {
+      $result->out->write('\Closure::fromCallable(');
+      $this->emitQuoted($result, $callable->expression);
+      $result->out->write(')');
+    }
   }
 }

src/main/php/lang/ast/emit/PHP81.class.php

@@ -22,6 +22,7 @@ class PHP81 extends PHP {
   use
     EmulatePipelines,
     RewriteBlockLambdaExpressions,
+    RewriteCallableClone,
     RewriteCloneWith,
     RewriteDynamicClassConstants,
     RewriteStaticVariableInitializations,

src/main/php/lang/ast/emit/PHP82.class.php

@@ -22,6 +22,7 @@ class PHP82 extends PHP {
   use
     EmulatePipelines,
     RewriteBlockLambdaExpressions,
+    RewriteCallableClone,
     RewriteCloneWith,
     RewriteDynamicClassConstants,
     RewriteStaticVariableInitializations,

src/main/php/lang/ast/emit/PHP84.class.php

@@ -19,7 +19,7 @@
  * @see  https://wiki.php.net/rfc#php_84
  */
 class PHP84 extends PHP {
-  use EmulatePipelines, RewriteCloneWith, RewriteBlockLambdaExpressions;
+  use EmulatePipelines, RewriteCallableClone, RewriteCloneWith, RewriteBlockLambdaExpressions;
 
   public $targetVersion= 80400;
 

src/main/php/lang/ast/emit/RewriteCallableClone.class.php

@@ -0,0 +1,15 @@
+<?php namespace lang\ast\emit;
+
+use lang\ast\nodes\Literal;
+
+/** @see https://wiki.php.net/rfc/clone_with_v2 */
+trait RewriteCallableClone {
+
+  protected function emitCallable($result, $callable) {
+    if ($callable->expression instanceof Literal && 'clone' === $callable->expression->expression) {
+      $result->out->write('fn($o) => clone $o');
+    } else {
+      parent::emitCallable($result, $callable);
+    }
+  }
+}

src/test/php/lang/ast/unittest/emit/CloningTest.class.php

@@ -126,8 +126,19 @@ public function run() {
     }'));
   }
 
-  #[Test, Values(['clone(...)', '"clone"', '$func']), Runtime(php: '>=8.5.0')]
-  public function clone_callable($expression) {
+  #[Test]
+  public function clone_callable() {
+    $clone= $this->run('class %T {
+      public function run($in) {
+        return array_map(clone(...), [$in])[0];
+      }
+    }', $this->fixture);
+
+    Assert::true($clone instanceof $this->fixture && $this->fixture !== $clone);
+  }
+
+  #[Test, Values(['"clone"', '$func']), Runtime(php: '>=8.5.0')]
+  public function clone_callable_reference($expression) {
     $clone= $this->run('class %T {
       public function run($in) {
         $func= "clone";