From 34b24331552a6c53b973bbf3d906d86ecc72001b Mon Sep 17 00:00:00 2001
From: doorgan <dorgandash@gmail.com>
Date: Tue, 8 Apr 2025 14:46:11 -0300
Subject: [PATCH] [fix] Fix `prefix_stream` crashing on interpolations with
 newlines

Interpolations with newlines contain an `:eol` token in the shape of
`{:eol, positions}`, which `get_start_pos` wasn't considering, causing a
crash.

The solution I went for here is to just consider that token shape when
dealing with interpolation tokens. As far as I can see the tokens inside
the interpolation aren't being normalized, so I kept that behavior.

The test I added uses the `~S` sigil instead of the helper `~q` sigil. This
is due to the `~q` sigil escaping the interpolation in a way that didn't
reproduce the issue I saw in an Expert release.

The code in the new test is the snippet that caused the crashes while editing
Sourceror, so to reproduce this locally it's enough to paste that into a
project and try to trigger a completion like `Enum|`.
---
 apps/common/lib/lexical/ast/tokens.ex        |  4 +++
 apps/common/test/lexical/ast/tokens_test.exs | 35 ++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/apps/common/lib/lexical/ast/tokens.ex b/apps/common/lib/lexical/ast/tokens.ex
index f7bf3026..f8c3494c 100644
--- a/apps/common/lib/lexical/ast/tokens.ex
+++ b/apps/common/lib/lexical/ast/tokens.ex
@@ -163,6 +163,10 @@ defmodule Lexical.Ast.Tokens do
     Enum.reverse(ranges)
   end
 
+  defp get_start_pos([{:eol, {start_line, start_column, _}} | _]) do
+    {start_line, start_column}
+  end
+
   defp get_start_pos([{_, {start_line, start_column, _}, _} | _]) do
     {start_line, start_column}
   end
diff --git a/apps/common/test/lexical/ast/tokens_test.exs b/apps/common/test/lexical/ast/tokens_test.exs
index 837b8fcb..15d1d215 100644
--- a/apps/common/test/lexical/ast/tokens_test.exs
+++ b/apps/common/test/lexical/ast/tokens_test.exs
@@ -47,5 +47,40 @@ defmodule Lexical.Ast.TokensTest do
 
       assert Enum.to_list(tokens) == []
     end
+
+    test "works on interpolations with newlines" do
+      text = ~S[
+          ~S"""
+          "foo«#{
+            2
+          }»bar"
+          """
+          |
+          ]
+
+      {position, document} = pop_cursor(text, as: :document)
+
+      tokens = Tokens.prefix_stream(document, position)
+
+      assert Enum.to_list(tokens) == [
+               {:eol, '\n', []},
+               {:eol, '\n', []},
+               {:eol, '\n', []},
+               {:eol, '\n', []},
+               {
+                 :interpolated_string,
+                 [
+                   {:literal, "foo«", {{1, 1}, {1, 5}}},
+                   {:interpolation,
+                    [{:eol, {3, 18, 1}}, {:int, {4, 13, 2}, '2'}, {:eol, {4, 14, 1}}],
+                    {{3, 18}, {5, 11}}},
+                   {:literal, "»bar", {{5, 11}, {5, 15}}}
+                 ],
+                 {3, 11}
+               },
+               {:eol, '\n', []},
+               {:eol, '\n', []}
+             ]
+    end
   end
 end