feat(lsp): Split out a diagnostics_to_items function from set_loclist

Makes it easier to re-use the logic to populate the quickfix list
instead of the location list.

runtime/doc/lsp.txt

@@ -1196,11 +1196,16 @@ get({bufnr}, {client_id})                           *vim.lsp.diagnostic.get()*
                                  diagnostics. Else, return just the
                                  diagnostics associated with the client_id.
 
-get_all()                                       *vim.lsp.diagnostic.get_all()*
-                Get all diagnostics for all clients
+get_all({client_id})                            *vim.lsp.diagnostic.get_all()*
+                Get all diagnostics for clients
+
+                Parameters: ~
+                    {client_id}  number Restrict included diagnostics to the
+                                 client If nil, diagnostics of all clients are
+                                 included.
 
                 Return: ~
-                    {bufnr:Diagnostic[]}
+                    table with diagnostics grouped by bufnr (bufnr:Diagnostic[])
 
                                               *vim.lsp.diagnostic.get_count()*
 get_count({bufnr}, {severity}, {client_id})
@@ -1725,6 +1730,19 @@ create_file({change})                             *vim.lsp.util.create_file()*
 delete_file({change})                             *vim.lsp.util.delete_file()*
                 TODO: Documentation
 
+                                         *vim.lsp.util.diagnostics_to_items()*
+diagnostics_to_items({diagnostics_by_bufnr}, {predicate})
+                Convert diagnostics grouped by bufnr to a list of items for
+                use in the quickfix or location list.
+
+                Parameters: ~
+                    {diagnostics_by_bufnr}  table bufnr -> Diagnostic []
+                    {predicate}             an optional function to filter the
+                                            diagnostics.
+
+                Return: ~
+                    table (A list of items)
+
                                      *vim.lsp.util.extract_completion_items()*
 extract_completion_items({result})
                 Can be used to extract the completion items from a `textDocument/completion` request, which may return one of `CompletionItem[]` , `CompletionList` or null.

runtime/lua/vim/lsp/diagnostic.lua

@@ -330,17 +330,21 @@ end
 -- Diagnostic Retrieval {{{
 
 
---- Get all diagnostics for all clients
+--- Get all diagnostics for clients
 ---
----@return {bufnr: Diagnostic[]}
-function M.get_all()
+---@param client_id number Restrict included diagnostics to the client
+---                        If nil, diagnostics of all clients are included.
+---@return table with diagnostics grouped by bufnr (bufnr: Diagnostic[])
+function M.get_all(client_id)
   local diagnostics_by_bufnr = {}
   for bufnr, buf_diagnostics in pairs(diagnostic_cache) do
     diagnostics_by_bufnr[bufnr] = {}
-    for _, client_diagnostics in pairs(buf_diagnostics) do
+    for cid, client_diagnostics in pairs(buf_diagnostics) do
+      if client_id == nil or cid == client_id then
         vim.list_extend(diagnostics_by_bufnr[bufnr], client_diagnostics)
       end
     end
+  end
   return diagnostics_by_bufnr
 end
 
@@ -1162,13 +1166,6 @@ function M.show_line_diagnostics(opts, bufnr, line_nr, client_id)
   return popup_bufnr, winnr
 end
 
-local loclist_type_map = {
-  [DiagnosticSeverity.Error] = 'E',
-  [DiagnosticSeverity.Warning] = 'W',
-  [DiagnosticSeverity.Information] = 'I',
-  [DiagnosticSeverity.Hint] = 'I',
-}
-
 
 --- Clear diagnotics and diagnostic cache
 ---
@@ -1201,51 +1198,24 @@ end
 ---             - Set the list with workspace diagnostics
 function M.set_loclist(opts)
   opts = opts or {}
-
   local open_loclist = if_nil(opts.open_loclist, true)
-
-  local win_id = vim.api.nvim_get_current_win()
-  local current_bufnr = vim.api.nvim_get_current_buf()
-  local diags = opts.workspace and M.get_all() or {
+  local current_bufnr = api.nvim_get_current_buf()
+  local diags = opts.workspace and M.get_all(opts.client_id) or {
     [current_bufnr] = M.get(current_bufnr, opts.client_id)
   }
-
-  local items = {}
-  local insert_diag = function(bufnr, diag)
-    local pos = diag.range.start
-    local row = pos.line
-
-    local col = util.character_offset(bufnr, row, pos.character) or 0
-
-    table.insert(items, {
-      bufnr = bufnr,
-      lnum = row + 1,
-      col = col + 1,
-      text = diag.message,
-      type = loclist_type_map[diag.severity or DiagnosticSeverity.Error] or 'E',
-    })
+  local predicate = function(d)
+    local severity = to_severity(opts.severity)
+    if severity then
+      return d.severity == severity
     end
-
-  for bufnr, diagnostic in pairs(diags) do
-    if opts.severity then
-      diagnostic = filter_to_severity_limit(opts.severity, diagnostic)
-    elseif opts.severity_limit then
-      diagnostic = filter_by_severity_limit(opts.severity_limit, diagnostic)
+    severity = to_severity(opts.severity_limit)
+    if severity then
+      return d.severity == severity
     end
-
-    for _, diag in ipairs(diagnostic) do
-      insert_diag(bufnr, diag)
+    return true
   end
-  end
-
-  table.sort(items, function(a, b)
-    if a.bufnr == b.bufnr then
-      return a.lnum < b.lnum
-    else
-      return a.bufnr < b.bufnr
-    end
-  end)
-
+  local items = util.diagnostics_to_items(diags, predicate)
+  local win_id = vim.api.nvim_get_current_win()
   util.set_loclist(items, win_id)
   if open_loclist then
     vim.cmd [[lopen]]

runtime/lua/vim/lsp/util.lua

@@ -30,6 +30,16 @@ local default_border = {
   {" ", "NormalFloat"},
 }
 
+
+local DiagnosticSeverity = protocol.DiagnosticSeverity
+local loclist_type_map = {
+  [DiagnosticSeverity.Error] = 'E',
+  [DiagnosticSeverity.Warning] = 'W',
+  [DiagnosticSeverity.Information] = 'I',
+  [DiagnosticSeverity.Hint] = 'I',
+}
+
+
 --@private
 -- Check the border given by opts or the default border for the additional
 -- size it adds to a float.
@@ -1878,6 +1888,40 @@ function M.lookup_section(settings, section)
   return settings
 end
 
+
+--- Convert diagnostics grouped by bufnr to a list of items for use in the
+--- quickfix or location list.
+---
+--@param diagnostics_by_bufnr table bufnr -> Diagnostic[]
+--@param predicate an optional function to filter the diagnostics.
+--                  If present, only diagnostic items matching will be included.
+--@return table (A list of items)
+function M.diagnostics_to_items(diagnostics_by_bufnr, predicate)
+  local items = {}
+  for bufnr, diagnostics in pairs(diagnostics_by_bufnr or {}) do
+    for _, d in pairs(diagnostics) do
+      if not predicate or predicate(d) then
+        table.insert(items, {
+          bufnr = bufnr,
+          lnum = d.range.start.line + 1,
+          col = d.range.start.character + 1,
+          text = d.message,
+          type = loclist_type_map[d.severity or DiagnosticSeverity.Error] or 'E'
+        })
+      end
+    end
+  end
+  table.sort(items, function(a, b)
+    if a.bufnr == b.bufnr then
+      return a.lnum < b.lnum
+    else
+      return a.bufnr < b.bufnr
+    end
+  end)
+  return items
+end
+
+
 M._get_line_byte_from_position = get_line_byte_from_position
 M._warn_once = warn_once
 

test/functional/plugin/lsp/diagnostic_spec.lua

@@ -86,6 +86,39 @@ describe('vim.lsp.diagnostic', function()
         eq(2, #result[1])
         eq('Diagnostic #1', result[1][1].message)
       end)
+      it('Can convert diagnostic to quickfix items format', function()
+        local bufnr = exec_lua([[
+          local fake_uri = ...
+          return vim.uri_to_bufnr(fake_uri)
+        ]], fake_uri)
+        local result = exec_lua([[
+          local bufnr = ...
+          vim.lsp.diagnostic.save(
+            {
+              make_error('Diagnostic #1', 1, 1, 1, 1),
+              make_error('Diagnostic #2', 2, 1, 2, 1),
+            }, bufnr, 1
+          )
+          return vim.lsp.util.diagnostics_to_items(vim.lsp.diagnostic.get_all())
+        ]], bufnr)
+        local expected = {
+          {
+            bufnr = bufnr,
+            col = 2,
+            lnum = 2,
+            text = 'Diagnostic #1',
+            type = 'E'
+          },
+          {
+            bufnr = bufnr,
+            col = 2,
+            lnum = 3,
+            text = 'Diagnostic #2',
+            type = 'E'
+          },
+        }
+        eq(expected, result)
+      end)
       it('should be able to save and count a single client error', function()
         eq(1, exec_lua [[
           vim.lsp.diagnostic.save(