Improve error messages

3 files changed, 28 insertions, 13 deletions

diff --git a/lib/elixir/src/elixir_tokenizer.erl b/lib/elixir/src/elixir_tokenizer.erl
index 18914e498..c5b810625 100644
--- a/lib/elixir/src/elixir_tokenizer.erl
+++ b/lib/elixir/src/elixir_tokenizer.erl
@@ -471,11 +471,11 @@ tokenize(String, Line, Column, Scope, Tokens) ->
           Reason = {Line, "keyword argument must be followed by space after: ", AtomName},
           {error, Reason, String, Tokens};
         _ when HasAt ->
-          Reason = {Line, invalid_character_error($@), atom_to_list(Atom)},
+          Reason = {Line, invalid_character_error(Kind, $@), atom_to_list(Atom)},
           {error, Reason, String, Tokens};
         _ when Kind == alias ->
           tokenize_alias(Rest, Line, Column, Atom, Length, Ascii, Special, Scope, Tokens);
-        _ when Kind == var ->
+        _ when Kind == identifier ->
           tokenize_other(Rest, Line, Column, Atom, Length, Scope, Tokens);
         _ ->
           unexpected_token(String, Line, Column, Tokens)
@@ -837,7 +837,7 @@ tokenize([H | T]) when ?is_upcase(H) ->
   {alias, lists:reverse(Acc), Rest, Length, true, Special};
 tokenize([H | T]) when ?is_downcase(H); H == $_ ->
   {Acc, Rest, Length, Special} = tokenize_continue(T, [H], 1, []),
-  {var, lists:reverse(Acc), Rest, Length, true, Special};
+  {identifier, lists:reverse(Acc), Rest, Length, true, Special};
 tokenize(_List) ->
   {error, empty}.
 
@@ -869,11 +869,12 @@ tokenize_alias(Rest, Line, Column, Atom, Length, Ascii, Special, Scope, Tokens)
   if
     not Ascii ->
       AtomName = atom_to_list(Atom),
-      Reason = {Line, "aliases must have only ascii characters", AtomName},
+      Invalid = hd([C || C <- AtomName, C > 127]),
+      Reason = {Line, invalid_character_error("alias (only ascii characters are allowed)", Invalid), AtomName},
       {error, Reason, AtomName ++ Rest, Tokens};
     Special /= [] ->
       AtomName = atom_to_list(Atom),
-      Reason = {Line, invalid_character_error(hd(Special)), AtomName},
+      Reason = {Line, invalid_character_error("alias", hd(Special)), AtomName},
       {error, Reason, AtomName ++ Rest, Tokens};
     true ->
       tokenize(Rest, Line, Column + Length, Scope, [{aliases, {Line, Column, Column + Length}, [Atom]} | Tokens])
@@ -1062,8 +1063,8 @@ keyword('catch')  -> block;
 
 keyword(_) -> false.
 
-invalid_character_error(Char) ->
-  io_lib:format("invalid character \"~ts\" (codepoint U+~4.16.0B) in token: ", [[Char], Char]).
+invalid_character_error(What, Char) ->
+  io_lib:format("invalid character \"~ts\" (codepoint U+~4.16.0B) in ~ts: ", [[Char], Char, What]).
 
 invalid_do_error(Prefix) ->
   Prefix ++ ". In case you wanted to write a \"do\" expression, "
diff --git a/lib/elixir/test/elixir/kernel/errors_test.exs b/lib/elixir/test/elixir/kernel/errors_test.exs
index bc67d627b..ecfffa49f 100644
--- a/lib/elixir/test/elixir/kernel/errors_test.exs
+++ b/lib/elixir/test/elixir/kernel/errors_test.exs
@@ -38,12 +38,26 @@ defmodule Kernel.ErrorsTest do
   end
 
   test "invalid identifier" do
-    msg = fn name -> "nofile:1: invalid character \"@\" (codepoint U+0040) in token: #{name}" end
+    message = fn name -> "nofile:1: invalid character \"@\" (codepoint U+0040) in identifier: #{name}" end
+    assert_compile_fail SyntaxError, message.("foo@"), 'foo@'
+    assert_compile_fail SyntaxError, message.("foo@"), 'foo@ '
+    assert_compile_fail SyntaxError, message.("foo@bar"), 'foo@bar'
 
-    assert_compile_fail SyntaxError, msg.("foo@"), 'foo@'
-    assert_compile_fail SyntaxError, msg.("foo@"), 'foo@ '
-    assert_compile_fail SyntaxError, msg.("foo@bar"), 'foo@bar'
-    assert_compile_fail SyntaxError, msg.("Foo@"), 'Foo@'
+    message = fn name -> "nofile:1: invalid character \"@\" (codepoint U+0040) in alias: #{name}" end
+    assert_compile_fail SyntaxError, message.("Foo@"), 'Foo@'
+    assert_compile_fail SyntaxError, message.("Foo@bar"), 'Foo@bar'
+
+    message = "nofile:1: invalid character \"!\" (codepoint U+0021) in alias: Foo!"
+    assert_compile_fail SyntaxError, message, 'Foo!'
+
+    message = "nofile:1: invalid character \"?\" (codepoint U+003F) in alias: Foo?"
+    assert_compile_fail SyntaxError, message, 'Foo?'
+
+    # TODO: Remove this check once we depend on OTP 20+
+    if :erlang.system_info(:otp_release) >= '20' do
+      message = "invalid character \"ó\" (codepoint U+00F3) in alias (only ascii characters are allowed): Foó"
+      assert_compile_fail SyntaxError, message, 'Foó'
+    end
   end
 
   test "invalid fn" do
diff --git a/lib/elixir/unicode/tokenizer.ex b/lib/elixir/unicode/tokenizer.ex
index d65a8a4b4..a3cf0bd38 100644
--- a/lib/elixir/unicode/tokenizer.ex
+++ b/lib/elixir/unicode/tokenizer.ex
@@ -140,7 +140,7 @@ defmodule String.Tokenizer do
       ascii_upper?(head) ->
         validate(continue(tail, [head], 1, true, []), :alias)
       ascii_start?(head) ->
-        validate(continue(tail, [head], 1, true, []), :var)
+        validate(continue(tail, [head], 1, true, []), :identifier)
       unicode_start?(head) or unicode_upper?(head) ->
         validate(continue(tail, [head], 1, false, []), :atom)
       true ->