perf(lua): avoid spairs in vim.validate happy path

Problem:

`vim.validate` is too slow, mainly because of `vim.spairs`.

Solution:

Collect all errors in via `pairs`, and sort the errors via `spairs`.

runtime/lua/vim/shared.lua

@@ -796,6 +796,61 @@ do
     return type(val) == t or (t == 'callable' and vim.is_callable(val))
   end
 
+  --- @param param_name string
+  --- @param spec vim.validate.Spec
+  --- @return string?
+  local function is_param_valid(param_name, spec)
+    if type(spec) ~= 'table' then
+      return string.format('opt[%s]: expected table, got %s', param_name, type(spec))
+    end
+
+    local val = spec[1] -- Argument value
+    local types = spec[2] -- Type name, or callable
+    local optional = (true == spec[3])
+
+    if type(types) == 'string' then
+      types = { types }
+    end
+
+    if vim.is_callable(types) then
+      -- Check user-provided validation function
+      local valid, optional_message = types(val)
+      if not valid then
+        local error_message =
+          string.format('%s: expected %s, got %s', param_name, (spec[3] or '?'), tostring(val))
+        if optional_message ~= nil then
+          error_message = string.format('%s. Info: %s', error_message, optional_message)
+        end
+
+        return error_message
+      end
+    elseif type(types) == 'table' then
+      local success = false
+      for i, t in ipairs(types) do
+        local t_name = type_names[t]
+        if not t_name then
+          return string.format('invalid type name: %s', t)
+        end
+        types[i] = t_name
+
+        if (optional and val == nil) or _is_type(val, t_name) then
+          success = true
+          break
+        end
+      end
+      if not success then
+        return string.format(
+          '%s: expected %s, got %s',
+          param_name,
+          table.concat(types, '|'),
+          type(val)
+        )
+      end
+    else
+      return string.format('invalid type name: %s', tostring(types))
+    end
+  end
+
   --- @param opt table<vim.validate.Type,vim.validate.Spec>
   --- @return boolean, string?
   local function is_valid(opt)
@@ -803,56 +858,19 @@ do
       return false, string.format('opt: expected table, got %s', type(opt))
     end
 
-    for param_name, spec in vim.spairs(opt) do
+    local report --- @type table<string,string>?
-      if type(spec) ~= 'table' then
+
-        return false, string.format('opt[%s]: expected table, got %s', param_name, type(spec))
+    for param_name, spec in pairs(opt) do
+      local msg = is_param_valid(param_name, spec)
+      if msg then
+        report = report or {}
+        report[param_name] = msg
       end
+    end
 
-      local val = spec[1] -- Argument value
+    if report then
-      local types = spec[2] -- Type name, or callable
+      for _, msg in vim.spairs(report) do -- luacheck: ignore
-      local optional = (true == spec[3])
+        return false, msg
-
-      if type(types) == 'string' then
-        types = { types }
-      end
-
-      if vim.is_callable(types) then
-        -- Check user-provided validation function
-        local valid, optional_message = types(val)
-        if not valid then
-          local error_message =
-            string.format('%s: expected %s, got %s', param_name, (spec[3] or '?'), tostring(val))
-          if optional_message ~= nil then
-            error_message = error_message .. string.format('. Info: %s', optional_message)
-          end
-
-          return false, error_message
-        end
-      elseif type(types) == 'table' then
-        local success = false
-        for i, t in ipairs(types) do
-          local t_name = type_names[t]
-          if not t_name then
-            return false, string.format('invalid type name: %s', t)
-          end
-          types[i] = t_name
-
-          if (optional and val == nil) or _is_type(val, t_name) then
-            success = true
-            break
-          end
-        end
-        if not success then
-          return false,
-            string.format(
-              '%s: expected %s, got %s',
-              param_name,
-              table.concat(types, '|'),
-              type(val)
-            )
-        end
-      else
-        return false, string.format('invalid type name: %s', tostring(types))
       end
     end