LSP: enable using different highlighting rules for LSP signs (#12176)

This commit creates 4 new highlight groups:
- LspDiagnosticsErrorSign
- LspDiagnosticsWarningSign
- LspDiagnosticsInformationSign
- LspDiagnosticsHintSign

These highlight groups are linked to their corresponding LspDiagnostics
highlight groups by default.

This lets users choose a different color for their sign columns and
virtualtext diagnostics.

2 files changed, 5 insertions, 4 deletions

diff --git a/runtime/lua/vim/lsp.lua b/runtime/lua/vim/lsp.lua
index c01b5d8e0c..4c1c52c796 100644
--- a/runtime/lua/vim/lsp.lua
+++ b/runtime/lua/vim/lsp.lua
@@ -1024,10 +1024,10 @@ do
       vim.fn.sign_define(name, properties)
     end
   end
-  define_default_sign('LspDiagnosticsErrorSign', {text='E', texthl='LspDiagnosticsError', linehl='', numhl=''})
-  define_default_sign('LspDiagnosticsWarningSign', {text='W', texthl='LspDiagnosticsWarning', linehl='', numhl=''})
-  define_default_sign('LspDiagnosticsInformationSign', {text='I', texthl='LspDiagnosticsInformation', linehl='', numhl=''})
-  define_default_sign('LspDiagnosticsHintSign', {text='H', texthl='LspDiagnosticsHint', linehl='', numhl=''})
+  define_default_sign('LspDiagnosticsErrorSign', {text='E', texthl='LspDiagnosticsErrorSign', linehl='', numhl=''})
+  define_default_sign('LspDiagnosticsWarningSign', {text='W', texthl='LspDiagnosticsWarningSign', linehl='', numhl=''})
+  define_default_sign('LspDiagnosticsInformationSign', {text='I', texthl='LspDiagnosticsInformationSign', linehl='', numhl=''})
+  define_default_sign('LspDiagnosticsHintSign', {text='H', texthl='LspDiagnosticsHintSign', linehl='', numhl=''})
 end
 
 return lsp
diff --git a/runtime/lua/vim/lsp/util.lua b/runtime/lua/vim/lsp/util.lua
index 9ca18cb2b1..7d4dc072e5 100644
--- a/runtime/lua/vim/lsp/util.lua
+++ b/runtime/lua/vim/lsp/util.lua
@@ -672,6 +672,7 @@ do
       table.insert(cmd_parts, k.."="..v)
     end
     api.nvim_command(table.concat(cmd_parts, ' '))
+    api.nvim_command('highlight link ' .. highlight_name .. 'Sign ' .. highlight_name)
     severity_highlights[severity] = highlight_name
   end