Deprecate macro calls without parentheses

CHANGELOG

@@ -7,6 +7,7 @@
  * Fix duplicated macro argument names triggering a PHP fatal error instead of a `SyntaxError`
  * Deprecate defining a macro more than once in the same template
  * Deprecate `TemplateVariable` and `AssignTemplateVariable`; use `MacroVariable` and `AssignMacroVariable` instead
+ * Deprecate omitting parentheses when calling a macro; it will throw a `SyntaxError` in 4.0
 
 # 3.28.0 (2026-07-03)
 

doc/deprecated.rst

@@ -318,6 +318,12 @@ Macros
   3.29 and will throw a ``SyntaxError`` in Twig 4.0. Give each macro a unique
   name.
 
+* Omitting parentheses when calling a macro (e.g. ``macros.input`` or
+  ``macros.(name)``) is deprecated as of Twig 3.29 and will throw a
+  ``SyntaxError`` in Twig 4.0. Add parentheses after the macro name (e.g.
+  ``macros.input()`` or ``macros.(name)()``). Parentheses remain optional when
+  testing whether a macro is defined.
+
 Filters
 -------
 

src/ExpressionParser/Infix/DotExpressionParser.php

@@ -77,11 +77,17 @@ public function parse(Parser $parser, AbstractExpression $expr, Token $token): A
             && \is_string($name = $attribute->getAttribute('value'))
             && preg_match('#^[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*$#D', $name)
         ) {
-            return new MacroReferenceExpression(new MacroVariable($expr->getAttribute('name'), $expr->getTemplateLine()), 'macro_'.$name, $arguments, $expr->getTemplateLine());
+            $node = new MacroReferenceExpression(new MacroVariable($expr->getAttribute('name'), $expr->getTemplateLine()), 'macro_'.$name, $arguments, $expr->getTemplateLine());
+            $node->setHasParentheses(Template::METHOD_CALL === $type);
+
+            return $node;
         }
 
         if ($isMacroTarget && !$attribute instanceof ConstantExpression) {
-            return new MacroReferenceExpression(new MacroVariable($expr->getAttribute('name'), $expr->getTemplateLine()), $attribute, $arguments, $expr->getTemplateLine());
+            $node = new MacroReferenceExpression(new MacroVariable($expr->getAttribute('name'), $expr->getTemplateLine()), $attribute, $arguments, $expr->getTemplateLine());
+            $node->setHasParentheses(Template::METHOD_CALL === $type);
+
+            return $node;
         }
 
         return new GetAttrExpression($expr, $attribute, $arguments, $type, $lineno, $nullSafe);

src/Node/Expression/MacroReferenceExpression.php

@@ -25,6 +25,8 @@ class MacroReferenceExpression extends AbstractExpression implements SupportDefi
     use SupportDefinedTestDeprecationTrait;
     use SupportDefinedTestTrait;
 
+    private bool $hasParentheses = true;
+
     /**
      * @param string|AbstractExpression $name A static macro method name (e.g. "macro_foo") or, for a dynamic
      *                                        call, an expression resolving to the macro name (without the
@@ -51,6 +53,14 @@ public function __construct(MacroVariable $template, string|AbstractExpression $
         parent::__construct($nodes, $attributes, $lineno);
     }
 
+    /**
+     * @internal
+     */
+    public function setHasParentheses(bool $hasParentheses): void
+    {
+        $this->hasParentheses = $hasParentheses;
+    }
+
     public function __clone()
     {
         // The template node must not be deep-cloned because its name is
@@ -63,6 +73,10 @@ public function __clone()
 
     public function compile(Compiler $compiler): void
     {
+        if (!$this->hasParentheses && !$this->definedTest) {
+            trigger_deprecation('twig/twig', '3.29', 'Omitting parentheses when calling a macro is deprecated and will throw a SyntaxError in Twig 4.0; add parentheses after the macro name in "%s" at line %d.', $this->getTemplateName(), $this->getTemplateLine());
+        }
+
         if ($this->hasNode('name')) {
             $this->compileDynamic($compiler);
 

tests/Fixtures/macros/call_without_parentheses.legacy.test

@@ -0,0 +1,16 @@
+--TEST--
+Omitting parentheses when calling macros is deprecated
+--DEPRECATION--
+Since twig/twig 3.29: Omitting parentheses when calling a macro is deprecated and will throw a SyntaxError in Twig 4.0; add parentheses after the macro name in "index.twig" at line 4.
+Since twig/twig 3.29: Omitting parentheses when calling a macro is deprecated and will throw a SyntaxError in Twig 4.0; add parentheses after the macro name in "index.twig" at line 5.
+--TEMPLATE--
+{% import _self as macros %}
+{% set name = 'hello' %}
+{{ macros.hello }}
+{{ _self.(name) }}
+{% macro hello() %}Hello{% endmacro %}
+--DATA--
+return []
+--EXPECT--
+Hello
+Hello