Raise clearer error message on number followed by identifiers, closes #…

…10755
elixir-lang · Mar 11, 2021 · 6b2cc23 · 6b2cc23
1 parent d8d26e9
commit 6b2cc23
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Showing 2 changed files with 17 additions and 2 deletions.
diff --git a/lib/elixir/src/elixir_tokenizer.erl b/lib/elixir/src/elixir_tokenizer.erl
@@ -493,8 +493,19 @@ tokenize([$: | String] = Original, Line, Column, Scope, Tokens) ->
 
 tokenize([H | T], Line, Column, Scope, Tokens) when ?is_digit(H) ->
   case tokenize_number(T, [H], 1, false) of
-    {error, Reason, Number} ->
-      {error, {Line, Column, Reason, Number}, T, Tokens};
+    {error, Reason, Original} ->
+      {error, {Line, Column, Reason, Original}, T, Tokens};
+    {[I | _], _Number, Original, _Length} when ?is_upcase(I); ?is_downcase(I); I == $_ ->
+      Msg =
+        io_lib:format(
+          "invalid character ~ts after number ~ts. If you intended to write a number, "
+          "make sure to add the proper punctuation character after the number (space, comma, etc). "
+          "If you meant to write an identifier, note that identifiers in Elixir cannot start with numbers. "
+          "Unexpected token: ",
+          [[I], Original]
+        ),
+
+      {error, {Line, Column, Msg, [I]}, T, Tokens};
     {Rest, Number, Original, Length} when is_integer(Number) ->
       Token = {int, {Line, Column, Number}, Original},
       tokenize(Rest, Line, Column + Length, Scope, [Token | Tokens]);

diff --git a/lib/elixir/test/elixir/kernel/errors_test.exs b/lib/elixir/test/elixir/kernel/errors_test.exs
@@ -1138,6 +1138,10 @@ defmodule Kernel.ErrorsTest do
     assert_eval_raise SyntaxError, "nofile:1:5: syntax error before: \"12\"", ':ok 12'
     assert_eval_raise SyntaxError, "nofile:1:5: syntax error before: \"0b1\"", ':ok 0b1'
     assert_eval_raise SyntaxError, "nofile:1:5: syntax error before: \"12.3\"", ':ok 12.3'
+
+    assert_eval_raise SyntaxError,
+                      ~r"nofile:1:1: invalid character _ after number 123_456",
+                      '123_456_foo'
   end
 
   test "invalid \"fn do expr end\"" do