feat(diagnostic): do not require namespace for hide() and show() (#16261)

Also fix a few other small bugs regarding saving and restoring extmarks.
In particular, now that the virtual text and underline handlers have
their own dedicated namespaces, they should be responsible for saving
and restoring their own extmarks. Also fix the wrong argument ordering
in the call to `clear_diagnostic_cache` in the `on_detach` callback.

runtime/lua/vim/diagnostic.lua

@@ -313,7 +313,7 @@ end
 
 ---@private
 local function save_extmarks(namespace, bufnr)
-  bufnr = bufnr == 0 and vim.api.nvim_get_current_buf() or bufnr
+  bufnr = get_bufnr(bufnr)
   if not diagnostic_attached_buffers[bufnr] then
     vim.api.nvim_buf_attach(bufnr, false, {
       on_lines = function(_, _, _, _, _, last)
@@ -606,7 +606,7 @@ function M.set(namespace, bufnr, diagnostics, opts)
       -- Clean up our data when the buffer unloads.
       vim.api.nvim_buf_attach(bufnr, false, {
         on_detach = function(_, b)
-          clear_diagnostic_cache(b, namespace)
+          clear_diagnostic_cache(namespace, b)
           diagnostic_cleanup[b][namespace] = nil
         end
       })
@@ -896,10 +896,12 @@ M.handlers.underline = {
         { diagnostic.end_lnum, diagnostic.end_col }
       )
     end
+    save_extmarks(underline_ns, bufnr)
   end,
   hide = function(namespace, bufnr)
     local ns = M.get_namespace(namespace)
     if ns.user_data.underline_ns then
+      diagnostic_cache_extmarks[bufnr][ns.user_data.underline_ns] = {}
       vim.api.nvim_buf_clear_namespace(bufnr, ns.user_data.underline_ns, 0, -1)
     end
   end
@@ -949,10 +951,12 @@ M.handlers.virtual_text = {
         })
       end
     end
+    save_extmarks(virt_text_ns, bufnr)
   end,
   hide = function(namespace, bufnr)
     local ns = M.get_namespace(namespace)
     if ns.user_data.virt_text_ns then
+      diagnostic_cache_extmarks[bufnr][ns.user_data.virt_text_ns] = {}
       vim.api.nvim_buf_clear_namespace(bufnr, ns.user_data.virt_text_ns, 0, -1)
     end
   end,
@@ -1025,43 +1029,54 @@ end
 --- To hide diagnostics and prevent them from re-displaying, use
 --- |vim.diagnostic.disable()|.
 ---
----@param namespace number The diagnostic namespace
+---@param namespace number|nil Diagnostic namespace. When omitted, hide
+---                            diagnostics from all namespaces.
 ---@param bufnr number|nil Buffer number. Defaults to the current buffer.
 function M.hide(namespace, bufnr)
   vim.validate {
-    namespace = { namespace, 'n' },
+    namespace = { namespace, 'n', true },
     bufnr = { bufnr, 'n', true },
   }
 
   bufnr = get_bufnr(bufnr)
-  diagnostic_cache_extmarks[bufnr][namespace] = {}
-
-  for _, handler in pairs(M.handlers) do
-    if handler.hide then
-      handler.hide(namespace, bufnr)
+  local namespaces = namespace and {namespace} or vim.tbl_keys(diagnostic_cache[bufnr])
+  for _, iter_namespace in ipairs(namespaces) do
+    for _, handler in pairs(M.handlers) do
+      if handler.hide then
+        handler.hide(iter_namespace, bufnr)
+      end
     end
   end
 end
 
 --- Display diagnostics for the given namespace and buffer.
 ---
----@param namespace number Diagnostic namespace.
+---@param namespace number|nil Diagnostic namespace. When omitted, show
+---                            diagnostics from all namespaces.
 ---@param bufnr number|nil Buffer number. Defaults to the current buffer.
 ---@param diagnostics table|nil The diagnostics to display. When omitted, use the
 ---                             saved diagnostics for the given namespace and
 ---                             buffer. This can be used to display a list of diagnostics
 ---                             without saving them or to display only a subset of
----                             diagnostics.
+---                             diagnostics. May not be used when {namespace} is nil.
 ---@param opts table|nil Display options. See |vim.diagnostic.config()|.
 function M.show(namespace, bufnr, diagnostics, opts)
   vim.validate {
-    namespace = { namespace, 'n' },
+    namespace = { namespace, 'n', true },
     bufnr = { bufnr, 'n', true },
     diagnostics = { diagnostics, 't', true },
     opts = { opts, 't', true },
   }
 
   bufnr = get_bufnr(bufnr)
+  if not namespace then
+    assert(not diagnostics, "Cannot show diagnostics without a namespace")
+    for iter_namespace in pairs(diagnostic_cache[bufnr]) do
+      M.show(iter_namespace, bufnr, nil, opts)
+    end
+    return
+  end
+
   if is_disabled(namespace, bufnr) then
     return
   end
@@ -1101,8 +1116,6 @@ function M.show(namespace, bufnr, diagnostics, opts)
       handler.show(namespace, bufnr, diagnostics, opts)
     end
   end
-
-  save_extmarks(namespace, bufnr)
 end
 
 --- Show diagnostics in a floating window.
@@ -1244,19 +1257,23 @@ end
 --- simply remove diagnostic decorations in a way that they can be
 --- re-displayed, use |vim.diagnostic.hide()|.
 ---
----@param namespace number
+---@param namespace number|nil Diagnostic namespace. When omitted, remove
+---                            diagnostics from all namespaces.
 ---@param bufnr number|nil Remove diagnostics for the given buffer. When omitted,
 ---             diagnostics are removed for all buffers.
 function M.reset(namespace, bufnr)
-  if bufnr == nil then
-    for iter_bufnr, namespaces in pairs(diagnostic_cache) do
-      if namespaces[namespace] then
-        M.reset(namespace, iter_bufnr)
-      end
+  vim.validate {
+    namespace = {namespace, 'n', true},
+    bufnr = {bufnr, 'n', true},
+  }
+
+  local buffers = bufnr and {bufnr} or vim.tbl_keys(diagnostic_cache)
+  for _, iter_bufnr in ipairs(buffers) do
+    local namespaces = namespace and {namespace} or vim.tbl_keys(diagnostic_cache[iter_bufnr])
+    for _, iter_namespace in ipairs(namespaces) do
+      clear_diagnostic_cache(iter_namespace, iter_bufnr)
+      M.hide(iter_namespace, iter_bufnr)
     end
-  else
-    clear_diagnostic_cache(namespace, bufnr)
-    M.hide(namespace, bufnr)
   end
 
   vim.api.nvim_command("doautocmd <nomodeline> User DiagnosticsChanged")