Add g:lsp_virtual_text_prefix option (#521)

This option allows prepending characters or text to the diagnostics
which are display as virtual text. It allows virtual text to be
differentiated from the code

Author: coditva

autoload/lsp/ui/vim/virtual.vim

@@ -81,7 +81,8 @@ function! s:place_virtual(server_name, path, diagnostics) abort
 
             let l:name = get(s:severity_sign_names_mapping, l:item['severity'], 'LspError')
             let l:hl_name = l:name . 'Text'
-            call nvim_buf_set_virtual_text(l:bufnr, l:ns, l:line, [[l:item['message'], l:hl_name]], {})
+            call nvim_buf_set_virtual_text(l:bufnr, l:ns, l:line,
+                        \ [[g:lsp_virtual_text_prefix . l:item['message'], l:hl_name]], {})
         endfor
     endif
 endfunction

doc/vim-lsp.txt

@@ -349,6 +349,19 @@ g:lsp_virtual_text_enabled                            *g:lsp_virtual_text_enable
 	let g:lsp_virtual_text_enabled = 0
 <
 
+g:lsp_virtual_text_prefix                            *g:lsp_virtual_text_prefix*
+    Type: |String|
+    Default: `""` for neovim 0.3+
+
+    Adds the prefix to the diagnostics to be shown as virtual text. Requires
+    NeoVim with version 0.3 or newer.
+
+    Example:
+>
+	let g:lsp_virtual_text_prefix = "> "
+	let g:lsp_virtual_text_prefix = " ‣ "
+<
+
 g:lsp_highlights_enabled                         *g:lsp_highlights_enabled*
     Type: |Number|
     Default: `1` for neovim 0.3+

plugin/lsp.vim

@@ -11,6 +11,7 @@ let g:lsp_debug_servers = get(g:, 'lsp_debug_servers', [])
 let g:lsp_signs_enabled = get(g:, 'lsp_signs_enabled', exists('*sign_define') && (has('nvim') || has('patch-8.1.0772')))
 let g:lsp_signs_priority = get(g:, 'lsp_signs_priority', 10)
 let g:lsp_virtual_text_enabled = get(g:, 'lsp_virtual_text_enabled', exists('*nvim_buf_set_virtual_text'))
+let g:lsp_virtual_text_prefix = get(g:, 'lsp_virtual_text_prefix', '')
 let g:lsp_highlights_enabled = get(g:, 'lsp_highlights_enabled', exists('*nvim_buf_add_highlight'))
 let g:lsp_textprop_enabled = get(g:, 'lsp_textprop_enabled', exists('*prop_add') && !g:lsp_highlights_enabled)
 let g:lsp_signs_error = get(g:, 'lsp_signs_error', {})