lsp: Add new highlight groups used in show_line_diagnostics (#12473)

* lsp: support custom hl groups in show_line_diagnostics

Closes #12472.

* runtime: add docs for the new lsp highlight groups

Co-authored-by: francisco souza <fsouza@users.noreply.github.com>

3 files changed, 33 insertions, 9 deletions

diff --git a/runtime/doc/lsp.txt b/runtime/doc/lsp.txt
index 3a93390210..f81265c2c8 100644
--- a/runtime/doc/lsp.txt
+++ b/runtime/doc/lsp.txt
@@ -164,21 +164,36 @@ name: >
 LSP HIGHLIGHT                                                    *lsp-highlight*
 
                                                         *hl-LspDiagnosticsError*
-LspDiagnosticsError           used for "Error" diagnostic virtual text
+LspDiagnosticsError               used for "Error" diagnostic virtual text
                                                     *hl-LspDiagnosticsErrorSign*
-LspDiagnosticsErrorSign       used for "Error" diagnostic signs in sign column
+LspDiagnosticsErrorSign           used for "Error" diagnostic signs in sign
+                                  column
+                                                *hl-LspDiagnosticsErrorFloating*
+LspDiagnosticsErrorFloating       used for "Error" diagnostic messages in the
+                                  diagnostics float
                                                       *hl-LspDiagnosticsWarning*
-LspDiagnosticsWarning         used for "Warning" diagnostic virtual text
+LspDiagnosticsWarning             used for "Warning" diagnostic virtual text
                                                   *hl-LspDiagnosticsWarningSign*
-LspDiagnosticsWarningSign     used for "Warning" diagnostic signs in sign column
+LspDiagnosticsWarningSign         used for "Warning" diagnostic signs in sign
+                                  column
+                                              *hl-LspDiagnosticsWarningFloating*
+LspDiagnosticsWarningFloating     used for "Warning" diagnostic messages in the
+                                  diagnostics float
                                                   *hl-LspDiagnosticsInformation*
-LspDiagnosticsInformation     used for "Information" diagnostic virtual text
+LspDiagnosticsInformation         used for "Information" diagnostic virtual text
                                               *hl-LspDiagnosticsInformationSign*
-LspDiagnosticsInformationSign used for "Information" signs in sign column
+LspDiagnosticsInformationSign     used for "Information" signs in sign column
+                                          *hl-LspDiagnosticsInformationFloating*
+LspDiagnosticsInformationFloating used for "Information" diagnostic messages in
+                                  the diagnostics float
                                                          *hl-LspDiagnosticsHint*
-LspDiagnosticsHint            used for "Hint" diagnostic virtual text
+LspDiagnosticsHint                used for "Hint" diagnostic virtual text
                                                      *hl-LspDiagnosticsHintSign*
-LspDiagnosticsHintSign        used for "Hint" diagnostic signs in sign column
+LspDiagnosticsHintSign            used for "Hint" diagnostic signs in sign
+                                  column
+                                                 *hl-LspDiagnosticsHintFloating*
+LspDiagnosticsHintFloating        used for "Hint" diagnostic messages in the
+                                  diagnostics float
                                                            *hl-LspReferenceText*
 LspReferenceText          used for highlighting "text" references
                                                            *hl-LspReferenceRead*
diff --git a/runtime/lua/vim/lsp/util.lua b/runtime/lua/vim/lsp/util.lua
index 4c3c4fa6cb..71ca1048e1 100644
--- a/runtime/lua/vim/lsp/util.lua
+++ b/runtime/lua/vim/lsp/util.lua
@@ -859,6 +859,8 @@ do
 
   local severity_highlights = {}
 
+  local severity_floating_highlights = {}
+
   local default_severity_highlight = {
     [protocol.DiagnosticSeverity.Error] = { guifg = "Red" };
     [protocol.DiagnosticSeverity.Warning] = { guifg = "Orange" };
@@ -870,6 +872,7 @@ do
   for severity, hi_info in pairs(default_severity_highlight) do
     local severity_name = protocol.DiagnosticSeverity[severity]
     local highlight_name = "LspDiagnostics"..severity_name
+    local floating_highlight_name = highlight_name.."Floating"
     -- Try to fill in the foreground color with a sane default.
     local cmd_parts = {"highlight", "default", highlight_name}
     for k, v in pairs(hi_info) do
@@ -877,7 +880,9 @@ do
     end
     api.nvim_command(table.concat(cmd_parts, ' '))
     api.nvim_command('highlight link ' .. highlight_name .. 'Sign ' .. highlight_name)
+    api.nvim_command('highlight link ' .. highlight_name .. 'Floating ' .. highlight_name)
     severity_highlights[severity] = highlight_name
+    severity_floating_highlights[severity] = floating_highlight_name
   end
 
   function M.buf_clear_diagnostics(bufnr)
@@ -926,7 +931,7 @@ do
 
       -- TODO(ashkan) make format configurable?
       local prefix = string.format("%d. ", i)
-      local hiname = severity_highlights[diagnostic.severity]
+      local hiname = severity_floating_highlights[diagnostic.severity]
       assert(hiname, 'unknown severity: ' .. tostring(diagnostic.severity))
       local message_lines = split_lines(diagnostic.message)
       table.insert(lines, prefix..message_lines[1])
diff --git a/test/functional/plugin/lsp_spec.lua b/test/functional/plugin/lsp_spec.lua
index 1ab81a0ef8..c74ed6bf3b 100644
--- a/test/functional/plugin/lsp_spec.lua
+++ b/test/functional/plugin/lsp_spec.lua
@@ -770,10 +770,13 @@ describe('LSP', function()
 
   it('highlight groups', function()
     eq({'LspDiagnosticsError',
+        'LspDiagnosticsErrorFloating',
         'LspDiagnosticsErrorSign',
         'LspDiagnosticsHint',
+        'LspDiagnosticsHintFloating',
         'LspDiagnosticsHintSign',
         'LspDiagnosticsInformation',
+        'LspDiagnosticsInformationFloating',
         'LspDiagnosticsInformationSign',
         'LspDiagnosticsUnderline',
         'LspDiagnosticsUnderlineError',
@@ -781,6 +784,7 @@ describe('LSP', function()
         'LspDiagnosticsUnderlineInformation',
         'LspDiagnosticsUnderlineWarning',
         'LspDiagnosticsWarning',
+        'LspDiagnosticsWarningFloating',
         'LspDiagnosticsWarningSign',
       },
       exec_lua([[require'vim.lsp'; return vim.fn.getcompletion('Lsp', 'highlight')]]))