Bring the "e in _" syntax back to try/rescue (#6360)

Author: whatyouhide

lib/elixir/src/elixir_clauses.erl

@@ -228,6 +228,11 @@ expand_rescue(Meta, _, E) ->
 expand_rescue({Name, _, Atom} = Var, E) when is_atom(Name), is_atom(Atom) ->
   match(fun elixir_expand:expand/2, Var, E);
 
+%% rescue var in _ => rescue var
+expand_rescue({in, _, [{Name, _, VarContext} = Var, {'_', _, UnderscoreContext}]}, E)
+    when is_atom(Name), is_atom(VarContext), is_atom(UnderscoreContext) ->
+  expand_rescue(Var, E);
+
 %% rescue var in [Exprs]
 expand_rescue({in, Meta, [Left, Right]}, E) ->
   {ELeft, EL}  = match(fun elixir_expand:expand/2, Left, E),

lib/elixir/test/elixir/kernel/raise_test.exs

@@ -229,6 +229,17 @@ defmodule Kernel.RaiseTest do
 
       assert result
     end
+
+    test "catch-all with \"x in _\" syntax" do
+      result = try do
+        raise "an exception"
+      rescue
+        exception in _ ->
+          Exception.message(exception)
+      end
+
+      assert result == "an exception"
+    end
   end
 
   describe "normalize" do