fix(lsp): check for configuration workspace folders when reusing clients

3 files changed, 40 insertions, 31 deletions

diff --git a/runtime/doc/lsp.txt b/runtime/doc/lsp.txt
index 2654d7f14f..1607f3492c 100644
--- a/runtime/doc/lsp.txt
+++ b/runtime/doc/lsp.txt
@@ -872,7 +872,9 @@ start({config}, {opts})                                      *vim.lsp.start()*
                     (`fun(client: vim.lsp.Client, config: vim.lsp.ClientConfig): boolean`)
                     Predicate used to decide if a client should be re-used.
                     Used on all running clients. The default implementation
-                    re-uses a client if name and root_dir matches.
+                    re-uses a client if it has the same name and if the given
+                    workspace folders (or root_dir) are all included in the
+                    client's workspace folders.
                   • {bufnr}? (`integer`) Buffer handle to attach to if
                     starting or re-using a client (0 for current).
                   • {attach}? (`boolean`) Whether to attach the client to a
diff --git a/runtime/lua/vim/lsp.lua b/runtime/lua/vim/lsp.lua
index 4717d7995a..b67b2d6988 100644
--- a/runtime/lua/vim/lsp.lua
+++ b/runtime/lua/vim/lsp.lua
@@ -114,6 +114,22 @@ function lsp._unsupported_method(method)
   return msg
 end
 
+---@private
+---@param workspace_folders string|lsp.WorkspaceFolder[]?
+---@return lsp.WorkspaceFolder[]?
+function lsp._get_workspace_folders(workspace_folders)
+  if type(workspace_folders) == 'table' then
+    return workspace_folders
+  elseif type(workspace_folders) == 'string' then
+    return {
+      {
+        uri = vim.uri_from_fname(workspace_folders),
+        name = workspace_folders,
+      },
+    }
+  end
+end
+
 local wait_result_reason = { [-1] = 'timeout', [-2] = 'interrupted', [-3] = 'error' }
 
 local format_line_ending = {
@@ -196,19 +212,24 @@ local function reuse_client_default(client, config)
     return false
   end
 
-  if config.root_dir then
-    local root = vim.uri_from_fname(config.root_dir)
-    for _, dir in ipairs(client.workspace_folders or {}) do
-      -- note: do not need to check client.root_dir since that should be client.workspace_folders[1]
-      if root == dir.uri then
-        return true
+  local config_folders = lsp._get_workspace_folders(config.workspace_folders or config.root_dir)
+    or {}
+  local config_folders_included = 0
+
+  if not next(config_folders) then
+    return false
+  end
+
+  for _, config_folder in ipairs(config_folders) do
+    for _, client_folder in ipairs(client.workspace_folders) do
+      if config_folder.uri == client_folder.uri then
+        config_folders_included = config_folders_included + 1
+        break
       end
     end
   end
 
-  -- TODO(lewis6991): also check config.workspace_folders
-
-  return false
+  return config_folders_included == #config_folders
 end
 
 --- Reset defaults set by `set_defaults`.
@@ -311,9 +332,10 @@ end
 --- @inlinedoc
 ---
 --- Predicate used to decide if a client should be re-used. Used on all
---- running clients. The default implementation re-uses a client if name and
---- root_dir matches.
---- @field reuse_client? (fun(client: vim.lsp.Client, config: vim.lsp.ClientConfig): boolean)
+--- running clients. The default implementation re-uses a client if it has the
+--- same name and if the given workspace folders (or root_dir) are all included
+--- in the client's workspace folders.
+--- @field reuse_client? fun(client: vim.lsp.Client, config: vim.lsp.ClientConfig): boolean
 ---
 --- Buffer handle to attach to if starting or re-using a client (0 for current).
 --- @field bufnr? integer
diff --git a/runtime/lua/vim/lsp/client.lua b/runtime/lua/vim/lsp/client.lua
index a83d75bf75..7eb023da39 100644
--- a/runtime/lua/vim/lsp/client.lua
+++ b/runtime/lua/vim/lsp/client.lua
@@ -365,21 +365,6 @@ local function get_name(id, config)
   return tostring(id)
 end
 
---- @param workspace_folders string|lsp.WorkspaceFolder[]?
---- @return lsp.WorkspaceFolder[]?
-local function get_workspace_folders(workspace_folders)
-  if type(workspace_folders) == 'table' then
-    return workspace_folders
-  elseif type(workspace_folders) == 'string' then
-    return {
-      {
-        uri = vim.uri_from_fname(workspace_folders),
-        name = workspace_folders,
-      },
-    }
-  end
-end
-
 --- @generic T
 --- @param x elem_or_list<T>?
 --- @return T[]
@@ -417,7 +402,7 @@ function Client.create(config)
     flags = config.flags or {},
     get_language_id = config.get_language_id or default_get_language_id,
     capabilities = config.capabilities or lsp.protocol.make_client_capabilities(),
-    workspace_folders = get_workspace_folders(config.workspace_folders or config.root_dir),
+    workspace_folders = lsp._get_workspace_folders(config.workspace_folders or config.root_dir),
     root_dir = config.root_dir,
     _before_init_cb = config.before_init,
     _on_init_cbs = ensure_list(config.on_init),
@@ -1174,7 +1159,7 @@ function Client:_add_workspace_folder(dir)
     end
   end
 
-  local wf = assert(get_workspace_folders(dir))
+  local wf = assert(lsp._get_workspace_folders(dir))
 
   self:notify(ms.workspace_didChangeWorkspaceFolders, {
     event = { added = wf, removed = {} },
@@ -1189,7 +1174,7 @@ end
 --- Remove a directory to the workspace folders.
 --- @param dir string?
 function Client:_remove_workspace_folder(dir)
-  local wf = assert(get_workspace_folders(dir))
+  local wf = assert(lsp._get_workspace_folders(dir))
 
   self:notify(ms.workspace_didChangeWorkspaceFolders, {
     event = { added = {}, removed = wf },