Add missing variable names in function definitions (#6194)

Author: eksperimental

lib/elixir/lib/exception.ex

@@ -170,6 +170,8 @@ defmodule Exception do
   """
   @spec blame(:error, any, stacktrace) :: {t, stacktrace}
   @spec blame(non_error_kind, payload, stacktrace) :: {payload, stacktrace} when payload: var
+  def blame(kind, error, stacktrace)
+
   def blame(:error, error, stacktrace) do
     case normalize(:error, error, stacktrace) do
       %{__struct__: FunctionClauseError} = struct ->

lib/elixir/lib/list.ex

@@ -600,6 +600,8 @@ defmodule List do
   @spec starts_with?(list, list) :: boolean
   @spec starts_with?(list, []) :: true
   @spec starts_with?([], nonempty_list) :: false
+  def starts_with?(list, prefix)
+
   def starts_with?([head | tail], [head | prefix_tail]),
     do: starts_with?(tail, prefix_tail);
   def starts_with?(list, []) when is_list(list),

lib/elixir/lib/map_set.ex

@@ -347,6 +347,8 @@ defmodule MapSet do
 
   """
   @spec union(t(val1), t(val2)) :: t(val1 | val2) when val1: value, val2: value
+  def union(map_set1, map_set2)
+
   def union(%MapSet{map: map1, version: version} = map_set, %MapSet{map: map2, version: version}) do
     %{map_set | map: Map.merge(map1, map2)}
   end

lib/mix/lib/mix/tasks/archive.install.ex

@@ -62,8 +62,7 @@ defmodule Mix.Tasks.Archive.Install do
   end
 
   # Callbacks
-
-  def check_install_spec({local_or_url, path_or_url}, _opts) when
+  def check_install_spec({local_or_url, path_or_url} = _install_spec, _opts) when
       local_or_url in [:local, :url] do
     if Path.extname(path_or_url) == ".ez" do
       :ok