From 3a60140dff06ecf6d55c21c9da5f00f5f5f4ff7e Mon Sep 17 00:00:00 2001
From: hideselfview <dminkovsky+github@gmail.com>
Date: Fri, 16 Jan 2026 18:47:47 -0500
Subject: [PATCH] fix: prevent dx fmt from adding trailing whitespace to blank
 lines (#5224)

This fixes a conflict between dx fmt and cargo fmt (rustfmt). Previously,
dx fmt would add indentation whitespace to blank lines inside RSX blocks,
but cargo fmt removes trailing whitespace from all lines. This made it
impossible for code to satisfy both formatters.

The fix skips adding indentation to empty lines in two places:
1. When indenting formatted RSX blocks inside expressions
2. When reassembling the final formatted output

Fixes #5223

Co-authored-by: Dmitry Minkovsky <dminkovsky@gmail.com>
---
 packages/autofmt/src/prettier_please.rs          | 13 ++++++++++---
 packages/autofmt/tests/samples.rs                |  2 ++
 packages/autofmt/tests/samples/blank_lines.rsx   | 16 ++++++++++++++++
 .../tests/samples/blank_lines_preserved.rsx      |  9 +++++++++
 4 files changed, 37 insertions(+), 3 deletions(-)
 create mode 100644 packages/autofmt/tests/samples/blank_lines.rsx
 create mode 100644 packages/autofmt/tests/samples/blank_lines_preserved.rsx

diff --git a/packages/autofmt/src/prettier_please.rs b/packages/autofmt/src/prettier_please.rs
index 0e0228325..2b24c9dbf 100644
--- a/packages/autofmt/src/prettier_please.rs
+++ b/packages/autofmt/src/prettier_please.rs
@@ -55,7 +55,14 @@ pub fn unparse_expr(expr: &Expr, src: &str, cfg: &IndentOptions) -> String {
                 if multiline || formatted.contains('\n') {
                     formatted = formatted
                         .lines()
-                        .map(|line| format!("{}{line}", self.cfg.indent_str()))
+                        .map(|line| {
+                            // Don't add indentation to blank lines (avoid trailing whitespace)
+                            if line.is_empty() {
+                                String::new()
+                            } else {
+                                format!("{}{line}", self.cfg.indent_str())
+                            }
+                        })
                         .collect::<Vec<_>>()
                         .join("\n");
                 }
@@ -106,8 +113,8 @@ pub fn unparse_expr(expr: &Expr, src: &str, cfg: &IndentOptions) -> String {
         let mut lines = fmted.lines().enumerate().peekable();
 
         while let Some((_idx, fmt_line)) = lines.next() {
-            // Push the indentation
-            if is_multiline {
+            // Push the indentation (but not for blank lines - avoid trailing whitespace)
+            if is_multiline && !fmt_line.is_empty() {
                 out_fmt.push_str(&cfg.indent_str().repeat(whitespace));
             }
 
diff --git a/packages/autofmt/tests/samples.rs b/packages/autofmt/tests/samples.rs
index 9e05c1aa8..b2ec30a75 100644
--- a/packages/autofmt/tests/samples.rs
+++ b/packages/autofmt/tests/samples.rs
@@ -62,4 +62,6 @@ twoway![
     asset,
     collapse,
     expr_on_conditional,
+    blank_lines,
+    blank_lines_preserved,
 ];
diff --git a/packages/autofmt/tests/samples/blank_lines.rsx b/packages/autofmt/tests/samples/blank_lines.rsx
new file mode 100644
index 000000000..816e8a859
--- /dev/null
+++ b/packages/autofmt/tests/samples/blank_lines.rsx
@@ -0,0 +1,16 @@
+rsx! {
+    div {
+        match true {
+            true => rsx! {
+                if true {
+                    span { "a" }
+                }
+                if true {
+                    span { "b" }
+                }
+                span { "c" }
+            },
+            false => rsx! {},
+        }
+    }
+}
diff --git a/packages/autofmt/tests/samples/blank_lines_preserved.rsx b/packages/autofmt/tests/samples/blank_lines_preserved.rsx
new file mode 100644
index 000000000..c35e64bb6
--- /dev/null
+++ b/packages/autofmt/tests/samples/blank_lines_preserved.rsx
@@ -0,0 +1,9 @@
+rsx! {
+    div {
+        span { "a" }
+
+        span { "b" }
+
+        span { "c" }
+    }
+}