From 5a55e839063a9b802de4280ab15f70ab244ec4db Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20Pokrywka?= <wolfmoon@o2.pl>
Date: Sat, 2 May 2026 14:02:13 +0200
Subject: [PATCH] Fixed `TwClass` in dynamic attribute

---
 .../src/html_parser/component.rs              | 20 +++++++----
 crates/vertigo/src/dom/dom_element.rs         |  1 +
 .../src/tests/dom/component_dynamic.rs        | 36 ++++++++++++++++++-
 docs/CHANGELOG.md                             |  1 +
 4 files changed, 50 insertions(+), 8 deletions(-)

diff --git a/crates/vertigo-macro/src/html_parser/component.rs b/crates/vertigo-macro/src/html_parser/component.rs
index 90d4df12..2b2a43eb 100644
--- a/crates/vertigo-macro/src/html_parser/component.rs
+++ b/crates/vertigo-macro/src/html_parser/component.rs
@@ -277,13 +277,19 @@ fn punctuated_attribute_to_tokens(
             .trim_start_matches(&format!("{}:", group.to_token_stream()))
             .to_string();
 
-        // If value name is 'tw' then register tailwind classes
-        if key == "tw"
-            && let Err(err) = add_to_tailwind(possible_value.to_token_stream())
-        {
-            emit_error!(possible_value.span(), err);
-            return None;
-        };
+        // If value name is 'tw' and it's a string literal, register tailwind classes.
+        // Block expressions like div:tw={my_tw_class} hold a pre-existing TwClass whose
+        // classes were already registered when tw!() was called — skip bundler tracing.
+        if key == "tw" {
+            let (block, _lit) =
+                take_block_or_literal_expr(possible_value, COMPONENT_ATTR_FORMAT_ERROR);
+            if block.is_none()
+                && let Err(err) = add_to_tailwind(possible_value.to_token_stream())
+            {
+                emit_error!(possible_value.span(), err);
+                return None;
+            }
+        }
 
         match group {
             Some(group) => {
diff --git a/crates/vertigo/src/dom/dom_element.rs b/crates/vertigo/src/dom/dom_element.rs
index 0935ce9a..518d4436 100644
--- a/crates/vertigo/src/dom/dom_element.rs
+++ b/crates/vertigo/src/dom/dom_element.rs
@@ -127,6 +127,7 @@ impl DomElement {
             }
             ("on_submit", AttrGroupValue::OnSubmit(on_submit))
             | ("form", AttrGroupValue::OnSubmit(on_submit)) => self.on_submit_rc(on_submit),
+            ("tw", AttrGroupValue::AttrValue(value)) => self.attr("class", value),
             (_, AttrGroupValue::AttrValue(value)) => self.attr(key, value),
             (_, _) => {
                 crate::log::error!("Invalid attribute type for key {key}");
diff --git a/crates/vertigo/src/tests/dom/component_dynamic.rs b/crates/vertigo/src/tests/dom/component_dynamic.rs
index 1550705e..2773a4cd 100644
--- a/crates/vertigo/src/tests/dom/component_dynamic.rs
+++ b/crates/vertigo/src/tests/dom/component_dynamic.rs
@@ -1,7 +1,7 @@
 use crate::{
     self as vertigo, AttrGroup, Computed, EmbedDom, component, css,
     dev::inspect::{DomDebugFragment, log_start},
-    dom,
+    dom, tw,
 };
 
 #[test]
@@ -99,6 +99,40 @@ fn test_css_attrs_grouping_and_spreading() {
     );
 }
 
+#[test]
+fn test_tw_attrs_grouping_and_spreading() {
+    #[component]
+    fn Hello<'a>(name: &'a str, div: AttrGroup, span: AttrGroup) {
+        dom! {
+            <div {..div}>
+                <span {..span}>
+                    "Hello " {name}
+                </span>
+            </div>
+        }
+    }
+
+    let red_css = tw!("px-3 bg-red-500");
+    let green_css = tw!("py-2 bg-green-500");
+
+    log_start();
+
+    let _el1 = dom! {
+        <Hello
+            name="world"
+            div:tw={red_css.clone()}
+            span:tw={green_css.clone()}
+        />
+    };
+
+    let el_str = DomDebugFragment::from_log().to_pseudo_html();
+
+    assert_eq!(
+        el_str,
+        "<div class='px-3 bg-red-500' v-component='Hello'><span class='py-2 bg-green-500'>Hello world</span></div>"
+    );
+}
+
 #[test]
 fn test_css_extending() {
     use vertigo::{AttrGroup, Value, component, css, dom};
diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index e3e4c3af..bd816a7a 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -11,6 +11,7 @@
 ### Fixed
 
 * Partially fixed SVG tags rendering, for full fix trace [#539]
+* `TwClass` in dynamic attribute (`dyn:tw={my_tw_class}`)
 
 ## 0.11.4 - 2026-04-18