From 2bdef6dd2a7572602aeb2efec76812769bcee246 Mon Sep 17 00:00:00 2001
From: zeertzjq <zeertzjq@outlook.com>
Date: Thu, 1 Jun 2023 16:20:31 +0800
Subject: [PATCH] fix(column): don't overflow sign column with extmark signs
 (#23854)

---
 src/nvim/decoration.c                   |  4 ++-
 test/functional/ui/decorations_spec.lua | 37 +++++++++++++++++++++++--
 2 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/src/nvim/decoration.c b/src/nvim/decoration.c
index 677bc25127..2027848ccf 100644
--- a/src/nvim/decoration.c
+++ b/src/nvim/decoration.c
@@ -433,7 +433,9 @@ void decor_redraw_signs(buf_T *buf, int row, int *num_signs, SignTextAttrs sattr
         if (sattrs[j - 1].priority >= decor->priority) {
           break;
         }
-        sattrs[j] = sattrs[j - 1];
+        if (j < SIGN_SHOW_MAX) {
+          sattrs[j] = sattrs[j - 1];
+        }
       }
       if (j < SIGN_SHOW_MAX) {
         sattrs[j] = (SignTextAttrs) {
diff --git a/test/functional/ui/decorations_spec.lua b/test/functional/ui/decorations_spec.lua
index 2d0223dec7..54441984a3 100644
--- a/test/functional/ui/decorations_spec.lua
+++ b/test/functional/ui/decorations_spec.lua
@@ -3342,8 +3342,8 @@ l5
     insert(example_test3)
     feed 'gg'
 
-    helpers.command('sign define Oldsign text=O3')
-    helpers.command([[exe 'sign place 42 line=1 name=Oldsign priority=10 buffer=' . bufnr('')]])
+    command('sign define Oldsign text=O3')
+    command([[exe 'sign place 42 line=1 name=Oldsign priority=10 buffer=' . bufnr('')]])
 
     meths.buf_set_extmark(0, ns, 0, -1, {sign_text='S4', priority=100})
     meths.buf_set_extmark(0, ns, 0, -1, {sign_text='S2', priority=5})
@@ -3366,6 +3366,39 @@ l5
     ]]}
   end)
 
+  it('does not overflow with many old signs #23852', function()
+    screen:try_resize(20, 3)
+
+    command('set signcolumn:auto:9')
+    command('sign define Oldsign text=O3')
+    command([[exe 'sign place 01 line=1 name=Oldsign priority=10 buffer=' . bufnr('')]])
+    command([[exe 'sign place 02 line=1 name=Oldsign priority=10 buffer=' . bufnr('')]])
+    command([[exe 'sign place 03 line=1 name=Oldsign priority=10 buffer=' . bufnr('')]])
+    command([[exe 'sign place 04 line=1 name=Oldsign priority=10 buffer=' . bufnr('')]])
+    command([[exe 'sign place 05 line=1 name=Oldsign priority=10 buffer=' . bufnr('')]])
+    command([[exe 'sign place 06 line=1 name=Oldsign priority=10 buffer=' . bufnr('')]])
+    command([[exe 'sign place 07 line=1 name=Oldsign priority=10 buffer=' . bufnr('')]])
+    command([[exe 'sign place 08 line=1 name=Oldsign priority=10 buffer=' . bufnr('')]])
+    command([[exe 'sign place 09 line=1 name=Oldsign priority=10 buffer=' . bufnr('')]])
+    screen:expect{grid=[[
+      O3O3O3O3O3O3O3O3O3^  |
+      {2:~                   }|
+                          |
+    ]]}
+
+    meths.buf_set_extmark(0, ns, 0, -1, {sign_text='S1', priority=1})
+    screen:expect_unchanged()
+
+    meths.buf_set_extmark(0, ns, 0, -1, {sign_text='S5', priority=200})
+    screen:expect{grid=[[
+      O3O3O3O3O3O3O3O3S5^  |
+      {2:~                   }|
+                          |
+    ]]}
+
+    assert_alive()
+  end)
+
   it('does not set signcolumn for signs without text', function()
     screen:try_resize(20, 3)
     meths.set_option_value('signcolumn', 'auto', {})