Improve container_cursor_to_quoted with trailing fragment, closes #14087

lib/elixir/lib/code/fragment.ex

@@ -1226,10 +1226,7 @@ defmodule Code.Fragment do
   defp maybe_missing_stab?([{:else, _} | _]), do: true
   defp maybe_missing_stab?([{:catch, _} | _]), do: true
   defp maybe_missing_stab?([{:rescue, _} | _]), do: true
-
   defp maybe_missing_stab?([{:stab_op, _, :->} | _]), do: false
-  defp maybe_missing_stab?([{:eol, _}, next | _]) when elem(next, 0) != :",", do: false
-
   defp maybe_missing_stab?([_ | tail]), do: maybe_missing_stab?(tail)
   defp maybe_missing_stab?([]), do: false
 end

lib/elixir/test/elixir/code_fragment_test.exs

@@ -1315,9 +1315,15 @@ defmodule CodeFragmentTest do
       assert cc2q!("(fn x ->", trailing_fragment: ":ok end)") ==
                s2q!("(fn x -> __cursor__() end)")
 
-      assert cc2q!("(fn x ->", trailing_fragment: ":ok end)") ==
+      assert cc2q!("(fn x ->", trailing_fragment: "\n:ok end)") ==
                s2q!("(fn x -> __cursor__() end)")
 
+      assert cc2q!("(fn x when ", trailing_fragment: "-> :ok end)") ==
+               s2q!("(fn x when __cursor__() -> :ok end)")
+
+      assert cc2q!("(fn x when ", trailing_fragment: "->\n:ok end)") ==
+               s2q!("(fn x when __cursor__() -> :ok end)")
+
       assert cc2q!("(fn") == s2q!("(__cursor__())")
       assert cc2q!("(fn x") == s2q!("(__cursor__())")
       assert cc2q!("(fn x,") == s2q!("(__cursor__())")
@@ -1327,6 +1333,23 @@ defmodule CodeFragmentTest do
       assert cc2q!("(fn x, y -> x + y end") == s2q!("(__cursor__())")
     end
 
+    test "do -> end" do
+      assert cc2q!("if do\nx ->\n", trailing_fragment: "y\nz ->\nw\nend") ==
+               s2q!("if do\nx ->\n__cursor__()\nend")
+
+      assert cc2q!("if do\nx ->\ny", trailing_fragment: "\nz ->\nw\nend") ==
+               s2q!("if do\nx ->\n__cursor__()\nend")
+
+      assert cc2q!("if do\nx ->\ny\n", trailing_fragment: "\nz ->\nw\nend") ==
+               s2q!("if do\nx ->\ny\n__cursor__()\nend")
+
+      assert cc2q!("for x <- [], reduce: %{} do\ny, ", trailing_fragment: "-> :ok\nend") ==
+               s2q!("for x <- [], reduce: %{} do\ny, __cursor__() -> :ok\nend")
+
+      assert cc2q!("for x <- [], reduce: %{} do\ny, z when ", trailing_fragment: "-> :ok\nend") ==
+               s2q!("for x <- [], reduce: %{} do\ny, z when __cursor__() -> :ok\nend")
+    end
+
     test "removes tokens until opening" do
       assert cc2q!("(123") == s2q!("(__cursor__())")
       assert cc2q!("[foo") == s2q!("[__cursor__()]")