Fix nested brace counting in MDX expressions

src/construct/partial_mdx_expression.rs

@@ -143,10 +143,9 @@ pub fn inside(tokenizer: &mut Tokenizer) -> State {
         tokenizer.exit(Name::MdxExpressionData);
         State::Retry(StateName::MdxExpressionBefore)
     } else {
-        // Don’t count if gnostic.
-        if tokenizer.current == Some(b'{')
-            && tokenizer.parse_state.options.mdx_expression_parse.is_none()
-        {
+        // Count braces even when external parser is present.
+        // Original check skipped nested braces, breaking `{{ x: 1 }}`.
+        if tokenizer.current == Some(b'{') {
             tokenizer.tokenize_state.size += 1;
         } else if tokenizer.current == Some(b'}') {
             tokenizer.tokenize_state.size -= 1;

tests/mdx_expression_text.rs

@@ -372,5 +372,29 @@ fn mdx_expression_text_gnostic() -> Result<(), message::Message> {
         "should keep the correct number of spaces in a blockquote (text)"
     );
 
+    assert_eq!(
+        to_html_with_options("a {{}} b", &swc)?,
+        "<p>a  b</p>",
+        "should support nested empty object literal"
+    );
+
+    assert_eq!(
+        to_html_with_options("a {{ x: 1 }} b", &swc)?,
+        "<p>a  b</p>",
+        "should support nested object literal with property"
+    );
+
+    assert_eq!(
+        to_html_with_options("a {func({ x: 1 })} b", &swc)?,
+        "<p>a  b</p>",
+        "should support function call with nested object"
+    );
+
+    assert_eq!(
+        to_html_with_options("a {f({ x: g({ y: 2 }) })} b", &swc)?,
+        "<p>a  b</p>",
+        "should support double nested function calls"
+    );
+
     Ok(())
 }