Do not allow defmodule with special atoms (#9032)

Fixes #9030

2 files changed, 16 insertions, 0 deletions

diff --git a/lib/elixir/src/elixir_module.erl b/lib/elixir/src/elixir_module.erl
index e05e2a675..016c7c67c 100644
--- a/lib/elixir/src/elixir_module.erl
+++ b/lib/elixir/src/elixir_module.erl
@@ -54,6 +54,8 @@ next_counter(Module) ->
 
 %% Compilation hook
 
+compile(Module, _Block, _Vars, #{line := Line, file := File}) when Module == nil; is_boolean(Module) ->
+  elixir_errors:form_error([{line, Line}], File, ?MODULE, {invalid_module, Module});
 compile(Module, Block, Vars, #{line := Line} = Env) when is_atom(Module) ->
   %% In case we are generating a module from inside a function,
   %% we get rid of the lexical tracker information as, at this
diff --git a/lib/elixir/test/elixir/kernel_test.exs b/lib/elixir/test/elixir/kernel_test.exs
index d07324be1..3c189423d 100644
--- a/lib/elixir/test/elixir/kernel_test.exs
+++ b/lib/elixir/test/elixir/kernel_test.exs
@@ -627,6 +627,20 @@ defmodule KernelTest do
     end
   end
 
+  describe "defmodule" do
+    test "does not accept special atoms as module names" do
+      special_atoms = [nil, true, false]
+
+      Enum.each(special_atoms, fn special_atom ->
+        msg = ~r"invalid module name: #{inspect(special_atom)}"
+
+        assert_raise CompileError, msg, fn ->
+          defmodule special_atom, do: :ok
+        end
+      end)
+    end
+  end
+
   describe "access" do
     defmodule StructAccess do
       defstruct [:foo, :bar]