Raise on invalid map syntax, closes #7268

Author: José Valim

lib/elixir/src/elixir_tokenizer.erl

@@ -473,6 +473,10 @@ tokenize("\r\n" ++ Rest, Line, Column, Scope, Tokens) ->
 
 % Others
 
+tokenize([$%, $[ | Rest], Line, _Column, _Scope, Tokens) ->
+  Reason = {Line, "expected %{ to define a map, got: ", [$%, $[]},
+  {error, Reason, Rest, Tokens};
+
 tokenize([$%, ${ | T], Line, Column, Scope, Tokens) ->
   tokenize([${ | T], Line, Column + 1, Scope, [{'%{}', {Line, Column, nil}} | Tokens]);
 

lib/elixir/test/elixir/kernel/errors_test.exs

@@ -108,6 +108,12 @@ defmodule Kernel.ErrorsTest do
     assert_eval_raise SyntaxError, msg, "foo:+1"
   end
 
+  test "invalid map start" do
+    assert_eval_raise SyntaxError,
+                      "nofile:1: expected %{ to define a map, got: %[",
+                      "{:ok, %[], %{}}"
+  end
+
   test "sigil terminator" do
     assert_eval_raise TokenMissingError,
                       "nofile:3: missing terminator: \" (for sigil ~r\" starting at line 1)",