Move raise checks to runtime callback, closes #5257

Signed-off-by: José Valim <jose.valim@plataformatec.com.br>

Author: José Valim

lib/elixir/lib/kernel.ex

@@ -1350,31 +1350,9 @@ defmodule Kernel do
           :erlang.error unquote(alias).exception([])
         end
       _ ->
-        generated = fn fun, var ->
-          {fun, [generated: true, line: -1], [{var, [], __MODULE__}]}
+        quote do
+          :erlang.error Kernel.Utils.raise(unquote(msg))
         end
-
-        {fun, meta, [arg, [do: clauses]]} =
-          quote do
-            case unquote(msg) do
-              msg when unquote(generated.(:is_binary, :msg)) ->
-                :erlang.error RuntimeError.exception(msg)
-              atom when unquote(generated.(:is_atom, :atom)) ->
-                :erlang.error atom.exception([])
-              %{__struct__: struct, __exception__: true} = other when is_atom(struct) ->
-                :erlang.error other
-              other ->
-                message = "raise/1 expects an alias, string or exception as the first argument, got: #{inspect other}"
-                :erlang.error ArgumentError.exception(message)
-            end
-          end
-
-        clauses =
-          :lists.map(fn {:->, meta, args} ->
-            {:->, [generated: true] ++ Keyword.put(meta, :line, -1), args}
-          end, clauses)
-
-        {fun, meta, [arg, [do: clauses]]}
     end
   end
 

lib/elixir/lib/kernel/utils.ex

@@ -3,6 +3,9 @@ import Kernel, except: [destructure: 2, defdelegate: 2, defstruct: 2]
 defmodule Kernel.Utils do
   @moduledoc false
 
+  @doc """
+  Callback for destructure.
+  """
   def destructure(list, count) when is_list(list), do: destructure_list(list, count)
   def destructure(nil, count), do: destructure_nil(count)
 
@@ -13,6 +16,9 @@ defmodule Kernel.Utils do
   defp destructure_nil(0), do: []
   defp destructure_nil(count), do: [nil | destructure_nil(count - 1)]
 
+  @doc """
+  Callback for defdelegate.
+  """
   def defdelegate(fun, opts) do
     append_first = Keyword.get(opts, :append_first, false)
 
@@ -56,6 +62,9 @@ defmodule Kernel.Utils do
       "defdelegate/2 only accepts function parameters, got: #{Macro.to_string(code)}"
   end
 
+  @doc """
+  Callback for defstruct.
+  """
   def defstruct(module, fields) do
     case fields do
       fs when is_list(fs) ->
@@ -85,10 +94,30 @@ defmodule Kernel.Utils do
      Module.get_attribute(module, :derive)}
   end
 
+  @doc """
+  Announcing callback for defstruct.
+  """
   def announce_struct(module) do
     case :erlang.get(:elixir_compiler_pid) do
       :undefined -> :ok
       pid -> send(pid, {:struct_available, module})
     end
   end
+
+  @doc """
+  Callback for raise.
+  """
+  def raise(msg) when is_binary(msg) do
+    RuntimeError.exception(msg)
+  end
+  def raise(atom) when is_atom(atom) do
+    atom.exception([])
+  end
+  def raise(%{__struct__: struct, __exception__: true} = exception) when is_atom(struct) do
+    exception
+  end
+  def raise(other) do
+    ArgumentError.exception("raise/1 expects an alias, string or exception as " <>
+                            "the first argument, got: #{inspect other}")
+  end
 end