From 3e2f68454556e5246b99b7645dca11501689093b Mon Sep 17 00:00:00 2001
From: Max Brunsfeld <maxbrunsfeld@gmail.com>
Date: Wed, 15 Dec 2021 18:30:09 -0800
Subject: [PATCH] Fix prev_row_boundary when a wrap follows a fold

Co-Authored-By: Nathan Sobo <nathan@zed.dev>
---
 crates/editor/src/display_map.rs          | 14 ++++++++++++--
 crates/editor/src/display_map/wrap_map.rs |  9 +++++++++
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/crates/editor/src/display_map.rs b/crates/editor/src/display_map.rs
index 2bea6536a2..220614ffd6 100644
--- a/crates/editor/src/display_map.rs
+++ b/crates/editor/src/display_map.rs
@@ -210,7 +210,7 @@ impl DisplaySnapshot {
             let mut point = display_point.to_point(self);
             point = self.buffer_snapshot.clip_point(point, Bias::Left);
             point.column = 0;
-            let next_display_point = self.point_to_display_point(point, Bias::Left);
+            let next_display_point = self.point_to_display_point_with_clipping(point, Bias::Left);
             if next_display_point == display_point {
                 return (display_point, point);
             }
@@ -252,6 +252,16 @@ impl DisplaySnapshot {
         DisplayPoint(block_point)
     }
 
+    fn point_to_display_point_with_clipping(&self, point: Point, bias: Bias) -> DisplayPoint {
+        let fold_point = point.to_fold_point(&self.folds_snapshot, bias);
+        let tab_point = self.tabs_snapshot.to_tab_point(fold_point);
+        let wrap_point = self
+            .wraps_snapshot
+            .from_tab_point_with_clipping(tab_point, bias);
+        let block_point = self.blocks_snapshot.to_block_point(wrap_point);
+        DisplayPoint(block_point)
+    }
+
     fn display_point_to_point(&self, point: DisplayPoint, bias: Bias) -> Point {
         let block_point = point.0;
         let wrap_point = self.blocks_snapshot.to_wrap_point(block_point);
@@ -492,7 +502,7 @@ mod tests {
     use Bias::*;
 
     #[gpui::test(iterations = 100)]
-    async fn test_random(mut cx: gpui::TestAppContext, mut rng: StdRng) {
+    async fn test_random_display_map(mut cx: gpui::TestAppContext, mut rng: StdRng) {
         cx.foreground().set_block_on_ticks(0..=50);
         cx.foreground().forbid_parking();
         let operations = env::var("OPERATIONS")
diff --git a/crates/editor/src/display_map/wrap_map.rs b/crates/editor/src/display_map/wrap_map.rs
index b674b467c9..0dd91b7404 100644
--- a/crates/editor/src/display_map/wrap_map.rs
+++ b/crates/editor/src/display_map/wrap_map.rs
@@ -672,6 +672,15 @@ impl WrapSnapshot {
         WrapPoint(cursor.start().1 .0 + (point.0 - cursor.start().0 .0))
     }
 
+    pub fn from_tab_point_with_clipping(&self, point: TabPoint, bias: Bias) -> WrapPoint {
+        let mut cursor = self.transforms.cursor::<(TabPoint, WrapPoint)>();
+        cursor.seek(&point, bias, &());
+        self.clip_point(
+            WrapPoint(cursor.start().1 .0 + (point.0 - cursor.start().0 .0)),
+            bias,
+        )
+    }
+
     pub fn clip_point(&self, mut point: WrapPoint, bias: Bias) -> WrapPoint {
         if bias == Bias::Left {
             let mut cursor = self.transforms.cursor::<WrapPoint>();