Raise CompileError in case of duplicated clauses given for receive

Author: lexmag

lib/elixir/src/elixir_exp_clauses.erl

@@ -81,6 +81,11 @@ do_cond(Meta, {Key, _}, _Acc, E) ->
 'receive'(Meta, KV, E) when not is_list(KV) ->
   compile_error(Meta, ?m(E, file), "invalid arguments for receive");
 'receive'(Meta, KV, E) ->
+  RaiseError = fun(Kind) ->
+    compile_error(Meta, ?m(E, file), "duplicated ~ts clauses given for receive", [Kind])
+  end,
+  ok = assert_at_most_once('do', KV, 0, RaiseError),
+  ok = assert_at_most_once('after', KV, 0, RaiseError),
   EE = E#{export_vars := []},
   {EClauses, EVars} = lists:mapfoldl(fun(X, Acc) -> do_receive(Meta, X, Acc, EE) end, [], KV),
   {EClauses, elixir_env:mergev(EVars, E)}.

lib/elixir/test/elixir/kernel/expansion_test.exs

@@ -385,6 +385,16 @@ defmodule Kernel.ExpansionTest do
            quote do: (receive do x -> x = x after y() -> y(); w = y() end; :erlang.+(x, w))
   end
 
+  test "receive: expects at most one clause" do
+    assert_raise CompileError, ~r"duplicated do clauses given for receive", fn ->
+      expand(quote(do: (receive do: (x -> x), do: (y -> y))))
+    end
+
+    assert_raise CompileError, ~r"duplicated after clauses given for receive", fn ->
+      expand(quote(do: (receive do x -> x after y -> y after z -> z end)))
+    end
+  end
+
   ## Try
 
   test "try: expands catch" do
@@ -415,7 +425,7 @@ defmodule Kernel.ExpansionTest do
 
   test "try: expects at most one clause" do
     assert_raise CompileError, ~r"duplicated do clauses given for try", fn ->
-      expand(quote(do: try(do: e, do: f)))
+      expand(quote(do: (try do: e, do: f)))
     end
 
     assert_raise CompileError, ~r"duplicated rescue clauses given for try", fn ->