From 2758b864bc7e314273ee4d4dfb74c2a4cb686541 Mon Sep 17 00:00:00 2001
From: Humza Shahid <humzasaur@gmail.com>
Date: Sat, 20 Sep 2025 18:04:59 +0100
Subject: [PATCH] fix bug found by unit test: when deleting leftwards, we
 should never delete beyond the end of the line

---
 fcore/normal-mode/make-normal-delete.sml | 16 +++++++++++++++-
 fcore/normal-mode/normal-mode.sml        |  2 +-
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/fcore/normal-mode/make-normal-delete.sml b/fcore/normal-mode/make-normal-delete.sml
index b4a2e1f..d7104ac 100644
--- a/fcore/normal-mode/make-normal-delete.sml
+++ b/fcore/normal-mode/make-normal-delete.sml
@@ -213,7 +213,7 @@ struct
 
   fun deleteByDfa (app: app_type, count, fMove, time) =
     let
-      val {buffer, cursorIdx, searchString, ...} = app
+      val {buffer, cursorIdx, ...} = app
 
       val buffer = LineGap.goToIdx (cursorIdx, buffer)
       val otherIdx = fMove (buffer, cursorIdx, count)
@@ -225,6 +225,20 @@ struct
       deleteAndFinish (app, low, length, buffer, time)
     end
 
+  fun deleteCharsLeft (app: app_type, count, time) =
+    let
+      val {buffer, cursorIdx, ...} = app
+
+      val buffer = LineGap.goToIdx (cursorIdx, buffer)
+      val startOfLine = Cursor.vi0 (buffer, cursorIdx)
+      val low = Cursor.viH (buffer, cursorIdx, count)
+      val low = if low < startOfLine then startOfLine else low
+
+      val length = cursorIdx - low
+    in
+      deleteAndFinish (app, low, length, buffer, time)
+    end
+
   fun deleteToEndOfPrevWord (app: app_type, count, time) =
     let
       val {buffer, cursorIdx, searchString, ...} = app
diff --git a/fcore/normal-mode/normal-mode.sml b/fcore/normal-mode/normal-mode.sml
index 5ef4a25..dd1a4e9 100644
--- a/fcore/normal-mode/normal-mode.sml
+++ b/fcore/normal-mode/normal-mode.sml
@@ -250,7 +250,7 @@ struct
     fun parseDeleteTerminal (str, count, app, chrCmd, time) =
       case chrCmd of
       (* terminal commands: require no input after *)
-        #"h" => NormalDelete.deleteByDfa (app, count, Cursor.viH, time)
+        #"h" => NormalDelete.deleteCharsLeft (app, count, time)
       | #"l" => NormalDelete.deleteByDfa (app, count, Cursor.viL, time)
       (* vi's 'j' and 'k' commands move up or down a column
        * but 'dj' or 'dk' delete whole lines