vim-patch:9.1.1018: v9.1.0743 causes regression with diff mode (#32047)

Problem:  v9.1.0743 causes regression with diff mode
Solution: Fix the regression with overlapping regions

closes: vim/vim#16454

https://github.com/vim/vim/commit/01f6509fb2de1627cc4ec2c109cd0aa2e3346d50

Co-authored-by: Yukihiro Nakadaira <yukihiro.nakadaira@gmail.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/test/functional/ui/diff_spec.lua b/test/functional/ui/diff_spec.lua
index 95159011f1..dae373297a 100644
--- a/test/functional/ui/diff_spec.lua
+++ b/test/functional/ui/diff_spec.lua
@@ -2044,6 +2044,26 @@ it('diff mode overlapped diff blocks will be merged', function()
     {2:Xdifile1    Xdifile2    }{3:Xdifile3   }|
                                        |
   ]])
+
+  WriteDiffFiles3('a\nb\nc', 'd\ne', 'b\nf')
+  screen:expect([[
+    {7:  }{27:a}{4:        }│{7:  }{27:d}{4:        }│{7:  }{27:^b}{4:        }|
+    {7:  }{27:b}{4:        }│{7:  }{27:e}{4:        }│{7:  }{27:f}{4:        }|
+    {7:  }{22:c        }│{7:  }{23:---------}│{7:  }{23:---------}|
+    {1:~          }│{1:~          }│{1:~          }|*15
+    {2:Xdifile1    Xdifile2    }{3:Xdifile3   }|
+                                       |
+  ]])
+
+  WriteDiffFiles3('a\nb\nc', 'd\ne', 'b')
+  screen:expect([[
+    {7:  }{27:a}{4:        }│{7:  }{27:d}{4:        }│{7:  }{27:^b}{4:        }|
+    {7:  }{27:b}{4:        }│{7:  }{27:e}{4:        }│{7:  }{23:---------}|
+    {7:  }{22:c        }│{7:  }{23:---------}│{7:  }{23:---------}|
+    {1:~          }│{1:~          }│{1:~          }|*15
+    {2:Xdifile1    Xdifile2    }{3:Xdifile3   }|
+                                       |
+  ]])
 end)
 
 -- oldtest: Test_diff_topline_noscroll()