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.

3 files changed, 101 insertions, 27 deletions

diff --git a/runtime/doc/diagnostic.txt b/runtime/doc/diagnostic.txt
index d121dba435..e2469b4f4e 100644
--- a/runtime/doc/diagnostic.txt
+++ b/runtime/doc/diagnostic.txt
@@ -536,7 +536,9 @@ hide({namespace}, {bufnr})                             *vim.diagnostic.hide()*
                 |vim.diagnostic.disable()|.
 
                 Parameters: ~
-                    {namespace}  number The diagnostic namespace
+                    {namespace}  number|nil Diagnostic namespace. When
+                                 omitted, hide diagnostics from all
+                                 namespaces.
                     {bufnr}      number|nil Buffer number. Defaults to the
                                  current buffer.
 
@@ -626,7 +628,9 @@ reset({namespace}, {bufnr})                           *vim.diagnostic.reset()*
                 |vim.diagnostic.hide()|.
 
                 Parameters: ~
-                    {namespace}  number
+                    {namespace}  number|nil Diagnostic namespace. When
+                                 omitted, remove diagnostics from all
+                                 namespaces.
                     {bufnr}      number|nil Remove diagnostics for the given
                                  buffer. When omitted, diagnostics are removed
                                  for all buffers.
@@ -677,7 +681,9 @@ show({namespace}, {bufnr}, {diagnostics}, {opts})
                 Display diagnostics for the given namespace and buffer.
 
                 Parameters: ~
-                    {namespace}    number Diagnostic namespace.
+                    {namespace}    number|nil Diagnostic namespace. When
+                                   omitted, show diagnostics from all
+                                   namespaces.
                     {bufnr}        number|nil Buffer number. Defaults to the
                                    current buffer.
                     {diagnostics}  table|nil The diagnostics to display. When
@@ -685,7 +691,8 @@ show({namespace}, {bufnr}, {diagnostics}, {opts})
                                    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.
+                                   subset of diagnostics. May not be used when
+                                   {namespace} is nil.
                     {opts}         table|nil Display options. See
                                    |vim.diagnostic.config()|.
 
diff --git a/runtime/lua/vim/diagnostic.lua b/runtime/lua/vim/diagnostic.lua
index 911d482bfd..d0f729f3b9 100644
--- a/runtime/lua/vim/diagnostic.lua
+++ b/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")
diff --git a/test/functional/lua/diagnostic_spec.lua b/test/functional/lua/diagnostic_spec.lua
index e8bbee671e..bb2d39c8b2 100644
--- a/test/functional/lua/diagnostic_spec.lua
+++ b/test/functional/lua/diagnostic_spec.lua
@@ -268,6 +268,56 @@ describe('vim.diagnostic', function()
     ]])
   end)
 
+  describe('show() and hide()', function()
+    it('works', function()
+      local result = exec_lua [[
+        vim.api.nvim_win_set_buf(0, diagnostic_bufnr)
+
+        local result = {}
+
+        vim.diagnostic.config({ underline = false, virtual_text = true })
+
+        local ns_1_diags = {
+          make_error("Error 1", 1, 1, 1, 5),
+          make_warning("Warning on Server 1", 2, 1, 2, 5),
+        }
+        local ns_2_diags = {
+          make_warning("Warning 1", 2, 1, 2, 5),
+        }
+
+        vim.diagnostic.set(diagnostic_ns, diagnostic_bufnr, ns_1_diags)
+        vim.diagnostic.set(other_ns, diagnostic_bufnr, ns_2_diags)
+
+        -- Both
+        table.insert(result, count_extmarks(diagnostic_bufnr, diagnostic_ns) + count_extmarks(diagnostic_bufnr, other_ns))
+
+        -- Hide one namespace
+        vim.diagnostic.hide(diagnostic_ns)
+        table.insert(result, count_extmarks(diagnostic_bufnr, diagnostic_ns))
+
+        -- Show one namespace
+        vim.diagnostic.show(diagnostic_ns)
+        table.insert(result, count_extmarks(diagnostic_bufnr, diagnostic_ns))
+
+        -- Hide all namespaces
+        vim.diagnostic.hide()
+        table.insert(result, count_extmarks(diagnostic_bufnr, diagnostic_ns) + count_extmarks(diagnostic_bufnr, other_ns))
+
+        -- Show all namespaces
+        vim.diagnostic.show()
+        table.insert(result, count_extmarks(diagnostic_bufnr, diagnostic_ns) + count_extmarks(diagnostic_bufnr, other_ns))
+
+        return result
+      ]]
+
+      eq(3, result[1])
+      eq(0, result[2])
+      eq(2, result[3])
+      eq(0, result[4])
+      eq(3, result[5])
+    end)
+  end)
+
   describe('reset()', function()
     it('diagnostic count is 0 and displayed diagnostics are 0 after call', function()
       -- 1 Error (1)