From bfe0acaea167a5ce18d4c63f65ccd45966203413 Mon Sep 17 00:00:00 2001
From: zeertzjq <zeertzjq@outlook.com>
Date: Mon, 23 Sep 2024 12:04:07 +0800
Subject: vim-patch:9.1.0740: incorrect internal diff with empty file (#30471)

Problem:  incorrect internal diff with an empty file
Solution: Set pointer to NULL, instead of using an empty line file
          (Yukihiro Nakadaira)

When using internal diff, empty file is read as one empty line file.
So result differs from external diff.

closes: vim/vim#15719

https://github.com/vim/vim/commit/f1694b439bb175d956b49da620f1253462ec507b

Co-authored-by: Yukihiro Nakadaira <yukihiro.nakadaira@gmail.com>
---
 test/functional/ui/diff_spec.lua | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

(limited to 'test/functional/ui/diff_spec.lua')

diff --git a/test/functional/ui/diff_spec.lua b/test/functional/ui/diff_spec.lua
index bad35dd2af..8db6f776d1 100644
--- a/test/functional/ui/diff_spec.lua
+++ b/test/functional/ui/diff_spec.lua
@@ -614,6 +614,34 @@ int main(int argc, char **argv)
     ]])
   end)
 
+  it('Diff empty and non-empty file', function()
+    write_file(fname, '', false)
+    write_file(fname_2, 'foo\nbar\nbaz', false)
+    reread()
+
+    feed(':set diffopt=filler<cr>')
+    screen:expect([[
+      {7:  }{23:------------------}│{7:  }{22:foo              }|
+      {7:  }{23:------------------}│{7:  }{22:bar              }|
+      {7:  }{23:------------------}│{7:  }{22:baz              }|
+      {7:  }^                  │{1:~                  }|
+      {1:~                   }│{1:~                  }|*10
+      {3:<onal-diff-screen-1  }{2:<l-diff-screen-1.2 }|
+      :set diffopt=filler                     |
+    ]])
+
+    feed(':set diffopt+=internal<cr>')
+    screen:expect([[
+      {7:  }{23:------------------}│{7:  }{22:foo              }|
+      {7:  }{23:------------------}│{7:  }{22:bar              }|
+      {7:  }{23:------------------}│{7:  }{22:baz              }|
+      {7:  }^                  │{1:~                  }|
+      {1:~                   }│{1:~                  }|*10
+      {3:<onal-diff-screen-1  }{2:<l-diff-screen-1.2 }|
+      :set diffopt+=internal                  |
+    ]])
+  end)
+
   it('diffopt+=icase', function()
     write_file(fname, 'a\nb\ncd\n', false)
     write_file(fname_2, 'A\nb\ncDe\n', false)
-- 
cgit