feat(lsp): add codeAction/resolve support (#15818)

Closes https://github.com/neovim/neovim/issues/15339 and https://github.com/neovim/neovim/issues/15828

5 files changed, 157 insertions, 72 deletions

diff --git a/runtime/lua/vim/lsp/buf.lua b/runtime/lua/vim/lsp/buf.lua
index 3e6a5ae2f1..245f29943e 100644
--- a/runtime/lua/vim/lsp/buf.lua
+++ b/runtime/lua/vim/lsp/buf.lua
@@ -450,6 +450,93 @@ function M.clear_references()
   util.buf_clear_references()
 end
 
+
+---@private
+--
+--- This is not public because the main extension point is
+--- vim.ui.select which can be overridden independently.
+---
+--- Can't call/use vim.lsp.handlers['textDocument/codeAction'] because it expects
+--- `(err, CodeAction[] | Command[], ctx)`, but we want to aggregate the results
+--- from multiple clients to have 1 single UI prompt for the user, yet we still
+--- need to be able to link a `CodeAction|Command` to the right client for
+--- `codeAction/resolve`
+local function on_code_action_results(results, ctx)
+  local action_tuples = {}
+  for client_id, result in pairs(results) do
+    for _, action in pairs(result.result or {}) do
+      table.insert(action_tuples, { client_id, action })
+    end
+  end
+  if #action_tuples == 0 then
+    vim.notify('No code actions available', vim.log.levels.INFO)
+    return
+  end
+
+  ---@private
+  local function apply_action(action, client)
+    if action.edit then
+      util.apply_workspace_edit(action.edit)
+    end
+    if action.command then
+      local command = type(action.command) == 'table' and action.command or action
+      local fn = vim.lsp.commands[command.command]
+      if fn then
+        local enriched_ctx = vim.deepcopy(ctx)
+        enriched_ctx.client_id = client.id
+        fn(command, ctx)
+      else
+        M.execute_command(command)
+      end
+    end
+  end
+
+  ---@private
+  local function on_user_choice(action_tuple)
+    if not action_tuple then
+      return
+    end
+    -- textDocument/codeAction can return either Command[] or CodeAction[]
+    --
+    -- CodeAction
+    --  ...
+    --  edit?: WorkspaceEdit    -- <- must be applied before command
+    --  command?: Command
+    --
+    -- Command:
+    --  title: string
+    --  command: string
+    --  arguments?: any[]
+    --
+    local client = vim.lsp.get_client_by_id(action_tuple[1])
+    local action = action_tuple[2]
+    if not action.edit
+        and client
+        and type(client.resolved_capabilities.code_action) == 'table'
+        and client.resolved_capabilities.code_action.resolveProvider then
+
+      client.request('codeAction/resolve', action, function(err, resolved_action)
+        if err then
+          vim.notify(err.code .. ': ' .. err.message, vim.log.levels.ERROR)
+          return
+        end
+        apply_action(resolved_action, client)
+      end)
+    else
+      apply_action(action, client)
+    end
+  end
+
+  vim.ui.select(action_tuples, {
+    prompt = 'Code actions:',
+    format_item = function(action_tuple)
+      local title = action_tuple[2].title:gsub('\r\n', '\\r\\n')
+      return title:gsub('\n', '\\n')
+    end,
+  }, on_user_choice)
+end
+
+
 --- Requests code actions from all clients and calls the handler exactly once
 --- with all aggregated results
 ---@private
@@ -457,11 +544,7 @@ local function code_action_request(params)
   local bufnr = vim.api.nvim_get_current_buf()
   local method = 'textDocument/codeAction'
   vim.lsp.buf_request_all(bufnr, method, params, function(results)
-    local actions = {}
-    for _, r in pairs(results) do
-      vim.list_extend(actions, r.result or {})
-    end
-    vim.lsp.handlers[method](nil, actions, {bufnr=bufnr, method=method})
+    on_code_action_results(results, { bufnr = bufnr, method = method, params = params })
   end)
 end
 
diff --git a/runtime/lua/vim/lsp/handlers.lua b/runtime/lua/vim/lsp/handlers.lua
index def83a7320..eff27807be 100644
--- a/runtime/lua/vim/lsp/handlers.lua
+++ b/runtime/lua/vim/lsp/handlers.lua
@@ -3,7 +3,6 @@ local protocol = require 'vim.lsp.protocol'
 local util = require 'vim.lsp.util'
 local vim = vim
 local api = vim.api
-local buf = require 'vim.lsp.buf'
 
 local M = {}
 
@@ -109,53 +108,6 @@ M['client/registerCapability'] = function(_, _, ctx)
   return vim.NIL
 end
 
---see: https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_codeAction
-M['textDocument/codeAction'] = function(_, result, ctx)
-  if result == nil or vim.tbl_isempty(result) then
-    print("No code actions available")
-    return
-  end
-
-  ---@private
-  local function on_user_choice(action)
-    if not action then
-      return
-    end
-    -- textDocument/codeAction can return either Command[] or CodeAction[]
-    --
-    -- CodeAction
-    --  ...
-    --  edit?: WorkspaceEdit    -- <- must be applied before command
-    --  command?: Command
-    --
-    -- Command:
-    --  title: string
-    --  command: string
-    --  arguments?: any[]
-    --
-    if action.edit then
-      util.apply_workspace_edit(action.edit)
-    end
-    if action.command then
-      local command = type(action.command) == 'table' and action.command or action
-      local fn = vim.lsp.commands[command.command]
-      if fn then
-        fn(command, ctx)
-      else
-        buf.execute_command(command)
-      end
-    end
-  end
-
-  vim.ui.select(result, {
-    prompt = 'Code actions:',
-    format_item = function(action)
-      local title = action.title:gsub('\r\n', '\\r\\n')
-      return title:gsub('\n', '\\n')
-    end,
-  }, on_user_choice)
-end
-
 --see: https://microsoft.github.io/language-server-protocol/specifications/specification-current/#workspace_applyEdit
 M['workspace/applyEdit'] = function(_, workspace_edit)
   if not workspace_edit then return end
diff --git a/runtime/lua/vim/lsp/protocol.lua b/runtime/lua/vim/lsp/protocol.lua
index 27703b4503..b3aa8b934f 100644
--- a/runtime/lua/vim/lsp/protocol.lua
+++ b/runtime/lua/vim/lsp/protocol.lua
@@ -645,6 +645,10 @@ function protocol.make_client_capabilities()
             end)();
           };
         };
+        dataSupport = true;
+        resolveSupport = {
+          properties = { 'edit', }
+        };
       };
       completion = {
         dynamicRegistration = false;
diff --git a/test/functional/fixtures/fake-lsp-server.lua b/test/functional/fixtures/fake-lsp-server.lua
index 297641849d..8e03d9a46e 100644
--- a/test/functional/fixtures/fake-lsp-server.lua
+++ b/test/functional/fixtures/fake-lsp-server.lua
@@ -564,6 +564,35 @@ function tests.decode_nil()
   }
 end
 
+
+function tests.code_action_with_resolve()
+  skeleton {
+    on_init = function()
+      return {
+        capabilities = {
+          codeActionProvider = {
+            resolveProvider = true
+          }
+        }
+      }
+    end;
+    body = function()
+      notify('start')
+      local cmd = {
+        title = 'Command 1',
+        command = 'dummy1'
+      }
+      expect_request('textDocument/codeAction', function()
+        return nil, { cmd, }
+      end)
+      expect_request('codeAction/resolve', function()
+        return nil, cmd
+      end)
+      notify('shutdown')
+    end;
+  }
+end
+
 -- Tests will be indexed by TEST_NAME
 
 local kill_timer = vim.loop.new_timer()
diff --git a/test/functional/plugin/lsp_spec.lua b/test/functional/plugin/lsp_spec.lua
index 27f2d2536f..572573a3a6 100644
--- a/test/functional/plugin/lsp_spec.lua
+++ b/test/functional/plugin/lsp_spec.lua
@@ -2376,26 +2376,43 @@ describe('LSP', function()
 
   describe('vim.lsp.buf.code_action', function()
     it('Calls client side command if available', function()
-      eq(1, exec_lua [[
-        local dummy_calls = 0
-        vim.lsp.commands.dummy = function()
-          dummy_calls = dummy_calls + 1
-        end
-        local actions = {
-          {
-            title = 'Dummy command',
-            command = 'dummy',
-          },
-        }
-        -- inputlist would require input and block the test;
-        vim.fn.inputlist = function()
-          return 1
+      local client
+      local expected_handlers = {
+        {NIL, {}, {method="shutdown", client_id=1}};
+        {NIL, {}, {method="start", client_id=1}};
+      }
+      test_rpc_server {
+        test_name = 'code_action_with_resolve',
+        on_init = function(client_)
+          client = client_
+        end,
+        on_setup = function()
+        end,
+        on_exit = function(code, signal)
+          eq(0, code, "exit code", fake_lsp_logfile)
+          eq(0, signal, "exit signal", fake_lsp_logfile)
+        end,
+        on_handler = function(err, result, ctx)
+          eq(table.remove(expected_handlers), {err, result, ctx})
+          if ctx.method == 'start' then
+            exec_lua([[
+              vim.lsp.commands['dummy1'] = function(cmd)
+                vim.lsp.commands['dummy2'] = function()
+                end
+              end
+              local bufnr = vim.api.nvim_get_current_buf()
+              vim.lsp.buf_attach_client(bufnr, TEST_RPC_CLIENT_ID)
+              vim.fn.inputlist = function()
+                return 1
+              end
+              vim.lsp.buf.code_action()
+            ]])
+          elseif ctx.method == 'shutdown' then
+            eq('function', exec_lua[[return type(vim.lsp.commands['dummy2'])]])
+            client.stop()
+          end
         end
-        local params = {}
-        local handler = require'vim.lsp.handlers'['textDocument/codeAction']
-        handler(nil, actions, { method = 'textDocument/codeAction', params = params }, nil)
-        return dummy_calls
-      ]])
+      }
     end)
   end)
   describe('vim.lsp.commands', function()