From 2032f409cfd7bf9091d8b0fc5b7baf80383e83cd Mon Sep 17 00:00:00 2001
From: Daniel Imms <2193314+Tyriar@users.noreply.github.com>
Date: Fri, 9 Sep 2022 12:28:27 -0700
Subject: [PATCH 1/2] Copy extended attributes to dest in reflow

Fixes #4108
---
 src/common/buffer/BufferLine.ts | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/common/buffer/BufferLine.ts b/src/common/buffer/BufferLine.ts
index eed87e6b..d8cb4355 100644
--- a/src/common/buffer/BufferLine.ts
+++ b/src/common/buffer/BufferLine.ts
@@ -5,7 +5,7 @@
 
 import { CharData, IBufferLine, ICellData, IAttributeData, IExtendedAttrs } from 'common/Types';
 import { stringFromCodePoint } from 'common/input/TextDecoder';
-import { CHAR_DATA_CHAR_INDEX, CHAR_DATA_WIDTH_INDEX, CHAR_DATA_ATTR_INDEX, NULL_CELL_CHAR, NULL_CELL_WIDTH, NULL_CELL_CODE, WHITESPACE_CELL_CHAR, Content, BgFlags } from 'common/buffer/Constants';
+import { CHAR_DATA_CHAR_INDEX, CHAR_DATA_WIDTH_INDEX, CHAR_DATA_ATTR_INDEX, NULL_CELL_CHAR, NULL_CELL_WIDTH, NULL_CELL_CODE, WHITESPACE_CELL_CHAR, Content, BgFlags, FgFlags } from 'common/buffer/Constants';
 import { CellData } from 'common/buffer/CellData';
 import { AttributeData, ExtendedAttrs } from 'common/buffer/AttributeData';
 
@@ -411,12 +411,18 @@ export class BufferLine implements IBufferLine {
         for (let i = 0; i < CELL_SIZE; i++) {
           this._data[(destCol + cell) * CELL_SIZE + i] = srcData[(srcCol + cell) * CELL_SIZE + i];
         }
+        if (srcData[(srcCol + cell) * CELL_SIZE + Cell.BG] & BgFlags.HAS_EXTENDED) {
+          this._extendedAttrs[destCol + cell] = src._extendedAttrs[srcCol + cell];
+        }
       }
     } else {
       for (let cell = 0; cell < length; cell++) {
         for (let i = 0; i < CELL_SIZE; i++) {
           this._data[(destCol + cell) * CELL_SIZE + i] = srcData[(srcCol + cell) * CELL_SIZE + i];
         }
+        if (srcData[(srcCol + cell) * CELL_SIZE + Cell.BG] & BgFlags.HAS_EXTENDED) {
+          this._extendedAttrs[destCol + cell] = src._extendedAttrs[srcCol + cell];
+        }
       }
     }
 

From 822ac527ba1f6a0930df81254daaab405a0098f0 Mon Sep 17 00:00:00 2001
From: Daniel Imms <2193314+Tyriar@users.noreply.github.com>
Date: Fri, 9 Sep 2022 12:48:55 -0700
Subject: [PATCH 2/2] Correct type and use ! to highlight the unsafe part

---
 src/common/buffer/BufferLine.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/common/buffer/BufferLine.ts b/src/common/buffer/BufferLine.ts
index d8cb4355..a1c7f257 100644
--- a/src/common/buffer/BufferLine.ts
+++ b/src/common/buffer/BufferLine.ts
@@ -60,7 +60,7 @@ const w: { startIndex: number } = {
 export class BufferLine implements IBufferLine {
   protected _data: Uint32Array;
   protected _combined: {[index: number]: string} = {};
-  protected _extendedAttrs: {[index: number]: IExtendedAttrs} = {};
+  protected _extendedAttrs: {[index: number]: IExtendedAttrs | undefined} = {};
   public length: number;
 
   constructor(cols: number, fillCellData?: ICellData, public isWrapped: boolean = false) {
@@ -181,7 +181,7 @@ export class BufferLine implements IBufferLine {
       cell.combinedData = this._combined[index];
     }
     if (cell.bg & BgFlags.HAS_EXTENDED) {
-      cell.extended = this._extendedAttrs[index];
+      cell.extended = this._extendedAttrs[index]!;
     }
     return cell;
   }