`dx fmt` corrupts source files with rsx inline `if/else` expressions

[rapporian]

Problem

Summary

dx fmt corrupts source code when a file contains a top-level comment and an inline if/else expression within an RSX attribute.

The formatter incorrectly duplicates the file's leading comment and injects it at the end of the if/else expression, right before the element's closing brace.

The specific failure chain is:

1. dx fmt copies the text from line 1 (e.g., // A comment...).

2. It pastes this text immediately after the else block inside the RSX.

3. Since the pasted text is a line comment (//), it comments out the closing brace } that follows it.

4. This leaves the RSX element unclosed, resulting in a compiler error

---

Minimal Reproduction

Step 1: Create this file (sample.rs)

// A comment about this file

use dioxus::prelude::*;

#[component]
pub fn Sample() -> Element {
    let is_active = use_signal(|| false);

    rsx! {
        div { class: if is_active() { "active" } else { "inactive" },
            div { class: if is_active() { "a" } else { "b" }}
        }
    }
}

Step 2: Run the formatter

dx fmt --file sample.rs

Step 3: Observe corrupted output

// A comment about this file

use dioxus::prelude::*;

#[component]
pub fn Sample() -> Element {
    let is_active = use_signal(|| false);

    rsx! {
        div { class: if is_active() { "active" } else { "inactive" },
            div { class: if is_active() { "a" } else { "b" } // A comment about this file }
        }
    }
}

The bug: The comment from line 1 (// A comment about this file) has been appended and the closing } has been commented out.

Workaround

• Remove all top level comments
• Wrap the rsx with if/else in an extra layer of {} brackets

Environment

• Dioxus CLI version: 0.7.2
• Rust version: 1.85.1
• OS: macOS 15.6.1 (arm64)