Fix repeated object destructuring evaluation

CHANGELOG

@@ -4,6 +4,8 @@
  * Fix `html_attr` JSON encoding a `Stringable` value in a `data-*` attribute instead of using its string representation
  * Add documentation comments to attach metadata to nodes (experimental)
  * Fix destructuring patterns with no variables, including sequences containing only empty slots, triggering a PHP fatal error instead of a `SyntaxError`
+ * Fix an empty destructuring pattern triggering a PHP fatal error instead of a `SyntaxError`
+ * Fix object and mapping destructuring evaluating the right-hand expression more than once
  * Fix sequence destructuring of iterators throwing a `TypeError`
  * Add `TempestMarkdown` to use `tempest/markdown` as the `markdown_to_html` converter
  * Fix imported macros not resolving their own template-level macro imports

src/Node/Expression/Binary/ObjectDestructuringSetBinary.php

@@ -53,6 +53,7 @@ class ObjectDestructuringSetBinary extends AbstractBinary
     public function compile(Compiler $compiler): void
     {
         $compiler->addDebugInfo($this);
+        $var = '$'.$compiler->getVarName();
         $compiler->raw('[');
         foreach ($this->mappings as $i => $mapping) {
             if ($i) {
@@ -65,7 +66,13 @@ class ObjectDestructuringSetBinary extends AbstractBinary
             if ($i) {
                 $compiler->raw(', ');
             }
-            $compiler->raw('CoreExtension::getAttribute($this->env, $this->source, ')->subcompile($this->getNode('right'))->raw(', ')->repr($mapping['property'])->raw(', [], \\Twig\\Template::ANY_CALL, false, false, ')->repr($compiler->getEnvironment()->hasExtension(SandboxExtension::class))->raw(', ')->repr($this->getNode('right')->getTemplateLine())->raw(')');
+            $compiler->raw('CoreExtension::getAttribute($this->env, $this->source, ');
+            if (0 === $i) {
+                $compiler->raw('('.$var.' = ')->subcompile($this->getNode('right'))->raw(')');
+            } else {
+                $compiler->raw($var);
+            }
+            $compiler->raw(', ')->repr($mapping['property'])->raw(', [], \\Twig\\Template::ANY_CALL, false, false, ')->repr($compiler->getEnvironment()->hasExtension(SandboxExtension::class))->raw(', ')->repr($this->getNode('right')->getTemplateLine())->raw(')');
         }
         $compiler->raw(']');
     }

tests/ExpressionParserTest.php

@@ -303,6 +303,20 @@ class ExpressionParserTest extends TestCase
         $this->assertSame('user_name', $pair['value']->getAttribute('name'));
     }
 
+    public function testObjectDestructuringEvaluatesRightHandExpressionOnce(): void
+    {
+        $calls = 0;
+        $env = new Environment(new ArrayLoader(['template' => '{% do [result_first, result_second] = ({first, second} = next_value()) %}{{ first }} {{ second }} {{ result_first }} {{ result_second }}']));
+        $env->addFunction(new TwigFunction('next_value', static function () use (&$calls): object {
+            ++$calls;
+
+            return (object) ['first' => $calls, 'second' => $calls];
+        }));
+
+        $this->assertSame('1 1 1 1', $env->render('template'));
+        $this->assertSame(1, $calls);
+    }
+
     /**
      * @dataProvider getTestsForString
      */