From cb24b0e8938df4412be22ce0a7f33eaca714bfbd Mon Sep 17 00:00:00 2001
From: Not-Sarthak <notsarthakshah@gmail.com>
Date: Sun, 10 May 2026 11:55:15 +0530
Subject: [PATCH] fix(autofmt): don't duplicate pretty continuation lines after
 multi-line source match

When prettier_please breaks a statement at a different line position than
the source did, the multi-line accumulator in write_partial_expr consumed
every source line for the logical statement but the outer iterator kept
walking pretty lines, re-emitting trailing continuations (e.g. `.clone();`)
and advancing the source pointer past unrelated statements - producing
invalid Rust.

Convert pretty.lines() to a peekable iterator and, after emitting a
multi-line verbatim source block whose accumulated content extends beyond
the matched pretty line, consume the following pretty continuation lines
whose content is already covered by the accumulated source.

Fixes #5523.
---
 packages/autofmt/src/writer.rs                | 26 ++++++++++++++++++-
 packages/autofmt/tests/samples.rs             |  6 +++++
 .../tests/samples/cfg_let_event_block.rsx     | 24 +++++++++++++++++
 3 files changed, 55 insertions(+), 1 deletion(-)
 create mode 100644 packages/autofmt/tests/samples/cfg_let_event_block.rsx

diff --git a/packages/autofmt/src/writer.rs b/packages/autofmt/src/writer.rs
index 00c33180ce..b7ad40b3d2 100644
--- a/packages/autofmt/src/writer.rs
+++ b/packages/autofmt/src/writer.rs
@@ -888,7 +888,8 @@ impl<'a> Writer<'a> {
         if src_lines.peek().is_none() {
             out = pretty;
         } else {
-            for line in pretty.lines() {
+            let mut pretty_iter = pretty.lines().peekable();
+            while let Some(line) = pretty_iter.next() {
                 let trimmed = line.trim();
                 let compacted = line.replace(" ", "").replace(",", "");
 
@@ -1062,6 +1063,29 @@ impl<'a> Writer<'a> {
                             out.push('\n');
                         }
                     }
+
+                    // Skip pretty continuation lines whose content was already
+                    // emitted as part of the verbatim multi-line source.
+                    if acc.len() > compacted.len() {
+                        let mut consumed_compact = compacted.clone();
+                        while consumed_compact.len() < acc.len() {
+                            let Some(next_pretty) = pretty_iter.peek() else {
+                                break;
+                            };
+                            let next_trimmed = next_pretty.trim();
+                            if next_trimmed.is_empty() || next_trimmed.starts_with("//") {
+                                break;
+                            }
+                            let next_compact = next_pretty.replace(" ", "").replace(",", "");
+                            let candidate = format!("{consumed_compact}{next_compact}");
+                            if acc.starts_with(&candidate) {
+                                consumed_compact = candidate;
+                                pretty_iter.next();
+                                continue;
+                            }
+                            break;
+                        }
+                    }
                 } else {
                     // Single line - output pretty line and capture inline comments
                     out.push_str(line);
diff --git a/packages/autofmt/tests/samples.rs b/packages/autofmt/tests/samples.rs
index d38cfef931..a143f159bb 100644
--- a/packages/autofmt/tests/samples.rs
+++ b/packages/autofmt/tests/samples.rs
@@ -74,6 +74,7 @@ twoway![
     commented_rsx_block_only,
     commented_rsx_block_between,
     commented_rsx_block_deep,
+    cfg_let_event_block,
 ];
 
 fn assert_idempotent(src: &str) {
@@ -109,3 +110,8 @@ fn comments_attr_expr_blocks_is_idempotent() {
 fn comments_expr_with_strings_is_idempotent() {
     assert_idempotent(include_str!("./samples/comments_expr_with_strings.rsx"));
 }
+
+#[test]
+fn cfg_let_event_block_is_idempotent() {
+    assert_idempotent(include_str!("./samples/cfg_let_event_block.rsx"));
+}
diff --git a/packages/autofmt/tests/samples/cfg_let_event_block.rsx b/packages/autofmt/tests/samples/cfg_let_event_block.rsx
new file mode 100644
index 0000000000..c4a2fe347b
--- /dev/null
+++ b/packages/autofmt/tests/samples/cfg_let_event_block.rsx
@@ -0,0 +1,24 @@
+rsx! {
+    button {
+        onclick: {
+            #[cfg(target_os = "android")]
+            let create_photo_collection_gallery = create_photo_collection.clone();
+
+            move |_| {
+                uploading.set(true);
+                error.set(String::new());
+
+                #[cfg(target_os = "android")]
+                let create_photo_collection_gallery_call =
+                    create_photo_collection_gallery.clone();
+
+                if let Err(err) = Err::<(), _>("x") {
+                    error.set(format!("{}: {}", "err", err));
+                    uploading.set(false);
+                    return;
+                }
+            }
+        },
+        "x"
+    }
+}