signs: support multiple columns #9295

closes #990
closes #9295

- Support for multiple auto-adjusted sign columns.
  With this change, having more than one sign on a line, and with the
  'auto' setting on 'signcolumn', extra columns will shown automatically
  to accomodate all the existing signs.

  For example, suppose we have this view:

   5147             }
   5148
   5149             return sign->typenr;
   5150         }
   5151     }
   5152     return 0;
   5153 }
   5154

  We have GitGutter installed, so it tells us about modified lines that
  are not commmited. So let's change line 5152:

     5147             }
     5148
     5149             return sign->typenr;
     5150         }
     5151     }
   ~ 5152     return 0;
     5153 }
     5154

  Now we add a mark over line 5152 using 'ma' in normal mode:

      5147             }
      5148
      5149             return sign->typenr;
      5150         }
      5151     }
  a ~ 5152     return 0;
      5153 }
      5154

  Previously, Vim/Nvim would have picked only one of the signs,
  because there was no support for having multiple signs in a line.

- Remove signs from deleted lines.
  Suppose we have highlights on a group of lines and we delete them:

   +     6 use std::ops::Deref;
   --+   7 use std::borrow::Cow;
   --+   8 use std::io::{Cursor};
         9 use proc_macro2::TokenStream;
        10 use syn::export::ToTokens;
   --+  11 use std::io::Write;
   >>   12 use std::ops::Deref;

  Without this change, these signs will momentarily accumulate in
  the sign column until the plugins wake up to refresh them.

  + --+ --+ --+ >>  6

  Discussion: It may be better to extend the API a bit and allow this
  to happen for only certain types of signs. For example, VIM marks
  and vim-gitgutter removal signs may want to be presreved, unlike
  line additions and linter highlights.

- 'signcolumn': support 'auto:NUM' and 'yes:NUM' settings
- sort signs according to id, from lowest to highest. If you have
  git-gutter, vim-signature, and ALE, it would appear in this order:
  git-gutter - vim-signature - ALE.
- recalculate size before screen update
- If no space for all signs, prefer the higher ids (while keeping the
  rendering order from low to high).
- Prevent duplicate signs. Duplicate signs were invisible to the user,
  before using our extended non-standard signcolumn settings.
- multi signcols: fix bug related to wrapped lines.
  In wrapped lines, the wrapped parts of a line did not include the extra
  columns if they existed. The result was a misdrawing of the wrapped
  parts. Fix the issue by:
    1. initializing the signcol counter to 0 when we are on a wrap boundary
    2. allowing for the draw of spaces in that case.

1 files changed, 109 insertions, 0 deletions

diff --git a/test/functional/ui/sign_spec.lua b/test/functional/ui/sign_spec.lua
index bc0e2e3799..c9821ef619 100644
--- a/test/functional/ui/sign_spec.lua
+++ b/test/functional/ui/sign_spec.lua
@@ -115,6 +115,115 @@ describe('Signs', function()
       ]])
     end)
 
+    it('multiple signs #9295', function()
+      feed('ia<cr>b<cr>c<cr><esc>')
+      command('set number')
+      command('set signcolumn=yes:2')
+      command('sign define pietSearch text=>> texthl=Search')
+      command('sign define pietError text=XX texthl=Error')
+      command('sign define pietWarn text=WW texthl=Warning')
+      command('sign place 1 line=1 name=pietSearch buffer=1')
+      command('sign place 2 line=1 name=pietError buffer=1')
+      -- Line 2 helps checking that signs in the same line are ordered by Id.
+      command('sign place 4 line=2 name=pietSearch buffer=1')
+      command('sign place 3 line=2 name=pietError buffer=1')
+      -- Line 3 checks that with a limit over the maximum number
+      -- of signs, the ones with the highest Ids are being picked,
+      -- and presented by their sorted Id order.
+      command('sign place 4 line=3 name=pietSearch buffer=1')
+      command('sign place 5 line=3 name=pietWarn buffer=1')
+      command('sign place 3 line=3 name=pietError buffer=1')
+      screen:expect([[
+        {1:>>}XX{6:  1 }a                                            |
+        XX{1:>>}{6:  2 }b                                            |
+        {1:>>}WW{6:  3 }c                                            |
+        {2:    }{6:  4 }^                                             |
+        {2:    }{0:~                                                }|
+        {2:    }{0:~                                                }|
+        {2:    }{0:~                                                }|
+        {2:    }{0:~                                                }|
+        {2:    }{0:~                                                }|
+        {2:    }{0:~                                                }|
+        {2:    }{0:~                                                }|
+        {2:    }{0:~                                                }|
+        {2:    }{0:~                                                }|
+                                                             |
+      ]])
+      -- With the default setting, we get the sign with the top id.
+      command('set signcolumn=yes:1')
+      screen:expect([[
+        XX{6:  1 }a                                              |
+        {1:>>}{6:  2 }b                                              |
+        WW{6:  3 }c                                              |
+        {2:  }{6:  4 }^                                               |
+        {2:  }{0:~                                                  }|
+        {2:  }{0:~                                                  }|
+        {2:  }{0:~                                                  }|
+        {2:  }{0:~                                                  }|
+        {2:  }{0:~                                                  }|
+        {2:  }{0:~                                                  }|
+        {2:  }{0:~                                                  }|
+        {2:  }{0:~                                                  }|
+        {2:  }{0:~                                                  }|
+                                                             |
+      ]])
+      -- "auto:3" accommodates all the signs we defined so far.
+      command('set signcolumn=auto:3')
+      screen:expect([[
+        {1:>>}XX{2:  }{6:  1 }a                                          |
+        XX{1:>>}{2:  }{6:  2 }b                                          |
+        XX{1:>>}WW{6:  3 }c                                          |
+        {2:      }{6:  4 }^                                           |
+        {2:      }{0:~                                              }|
+        {2:      }{0:~                                              }|
+        {2:      }{0:~                                              }|
+        {2:      }{0:~                                              }|
+        {2:      }{0:~                                              }|
+        {2:      }{0:~                                              }|
+        {2:      }{0:~                                              }|
+        {2:      }{0:~                                              }|
+        {2:      }{0:~                                              }|
+                                                             |
+      ]])
+      -- Check "yes:9".
+      command('set signcolumn=yes:9')
+      screen:expect([[
+        {1:>>}XX{2:              }{6:  1 }a                              |
+        XX{1:>>}{2:              }{6:  2 }b                              |
+        XX{1:>>}WW{2:            }{6:  3 }c                              |
+        {2:                  }{6:  4 }^                               |
+        {2:                  }{0:~                                  }|
+        {2:                  }{0:~                                  }|
+        {2:                  }{0:~                                  }|
+        {2:                  }{0:~                                  }|
+        {2:                  }{0:~                                  }|
+        {2:                  }{0:~                                  }|
+        {2:                  }{0:~                                  }|
+        {2:                  }{0:~                                  }|
+        {2:                  }{0:~                                  }|
+                                                             |
+      ]])
+      -- Check "auto:N" larger than the maximum number of signs defined in
+      -- a single line (same result as "auto:3").
+      command('set signcolumn=auto:4')
+      screen:expect{grid=[[
+        {1:>>}XX{2:  }{6:  1 }a                                          |
+        XX{1:>>}{2:  }{6:  2 }b                                          |
+        XX{1:>>}WW{6:  3 }c                                          |
+        {2:      }{6:  4 }^                                           |
+        {2:      }{0:~                                              }|
+        {2:      }{0:~                                              }|
+        {2:      }{0:~                                              }|
+        {2:      }{0:~                                              }|
+        {2:      }{0:~                                              }|
+        {2:      }{0:~                                              }|
+        {2:      }{0:~                                              }|
+        {2:      }{0:~                                              }|
+        {2:      }{0:~                                              }|
+                                                             |
+      ]]}
+    end)
+
     it('can have 32bit sign IDs', function()
       command('sign define piet text=>> texthl=Search')
       command('sign place 100000 line=1 name=piet buffer=1')