Support escaping of terminators in uppercase sigils heredocs for consistency, closes #11390

Author: josevalim

lib/elixir/lib/code/formatter.ex

@@ -270,7 +270,7 @@ defmodule Code.Formatter do
         {doc, state} =
           entries
           |> prepend_heredoc_line()
-          |> interpolation_to_algebra(:heredoc, state, @double_heredoc, @double_heredoc)
+          |> interpolation_to_algebra(~s["""], state, @double_heredoc, @double_heredoc)
 
         {force_unfit(doc), state}
 
@@ -292,7 +292,7 @@ defmodule Code.Formatter do
         {doc, state} =
           entries
           |> prepend_heredoc_line()
-          |> list_interpolation_to_algebra(:heredoc, state, @single_heredoc, @single_heredoc)
+          |> list_interpolation_to_algebra(~s['''], state, @single_heredoc, @single_heredoc)
 
         {force_unfit(doc), state}
 
@@ -355,7 +355,7 @@ defmodule Code.Formatter do
   defp quoted_to_algebra({:__block__, meta, [list]}, _context, state) when is_list(list) do
     case meta[:delimiter] do
       ~s['''] ->
-        string = list |> List.to_string() |> escape_heredoc()
+        string = list |> List.to_string() |> escape_heredoc(~s['''])
         {@single_heredoc |> concat(string) |> concat(@single_heredoc) |> force_unfit(), state}
 
       ~s['] ->
@@ -369,7 +369,7 @@ defmodule Code.Formatter do
 
   defp quoted_to_algebra({:__block__, meta, [string]}, _context, state) when is_binary(string) do
     if meta[:delimiter] == ~s["""] do
-      string = escape_heredoc(string)
+      string = escape_heredoc(string, ~s["""])
       {@double_heredoc |> concat(string) |> concat(@double_heredoc) |> force_unfit(), state}
     else
       string = escape_string(string, @double_quote)
@@ -1339,7 +1339,7 @@ defmodule Code.Formatter do
         {doc, state} =
           entries
           |> prepend_heredoc_line()
-          |> interpolation_to_algebra(:heredoc, state, doc, closing_delimiter)
+          |> interpolation_to_algebra(opening_delimiter, state, doc, closing_delimiter)
 
         {force_unfit(doc), state}
       else
@@ -1548,11 +1548,13 @@ defmodule Code.Formatter do
     end
   end
 
-  defp escape_heredoc(string) do
+  defp escape_heredoc(string, escape) do
+    string = String.replace(string, escape, "\\" <> escape)
     heredoc_to_algebra(["" | String.split(string, "\n")])
   end
 
-  defp escape_string(string, :heredoc) do
+  defp escape_string(string, <<_, _, _>> = escape) do
+    string = String.replace(string, escape, "\\" <> escape)
     heredoc_to_algebra(String.split(string, "\n"))
   end
 

lib/elixir/src/elixir_interpolation.erl

@@ -37,6 +37,9 @@ extract([$\n | Rest], Buffer, Output, Line, _Column, Scope, Interpol, Last) ->
 extract([$\\, Last | Rest], Buffer, Output, Line, Column, Scope, Interpol, Last) ->
   extract(Rest, [Last | Buffer], Output, Line, Column+2, Scope, Interpol, Last);
 
+extract([$\\, Last, Last, Last | Rest], Buffer, Output, Line, Column, Scope, Interpol, [Last, Last, Last] = All) ->
+  extract(Rest, [Last, Last, Last | Buffer], Output, Line, Column+4, Scope, Interpol, All);
+
 extract([$\\, $#, ${ | Rest], Buffer, Output, Line, Column, Scope, true, Last) ->
   extract(Rest, [${, $#, $\\ | Buffer], Output, Line, Column+1, Scope, true, Last);
 

lib/elixir/test/elixir/kernel/binary_test.exs

@@ -47,6 +47,15 @@ defmodule Kernel.BinaryTest do
              )
   end
 
+  test "heredoc with heredoc inside interpolation" do
+    assert """
+           1
+           #{"""
+           2
+           """}
+           """ == "1\n2\n\n"
+  end
+
   test "UTF-8" do
     assert byte_size(" ゆんゆん") == 13
   end

lib/elixir/test/elixir/kernel/sigils_test.exs

@@ -42,6 +42,14 @@ bar) in ["foo\\\nbar", "foo\\\r\nbar"]
            """
   end
 
+  test "sigil S with escaping" do
+    assert "\"" == ~S"\""
+
+    assert "\"\"\"\n" == ~S"""
+           \"""
+           """
+  end
+
   test "sigil s/S expand to binary when possible" do
     assert Macro.expand(quote(do: ~s(foo)), __ENV__) == "foo"
     assert Macro.expand(quote(do: ~S(foo)), __ENV__) == "foo"

lib/elixir/test/elixir/string_test.exs

@@ -5,15 +5,6 @@ defmodule StringTest do
 
   doctest String
 
-  test "heredoc with heredoc inside interpolation" do
-    assert """
-           1
-           #{"""
-           2
-           """}
-           """ == "1\n2\n\n"
-  end
-
   test "next_codepoint/1" do
     assert String.next_codepoint("ésoj") == {"é", "soj"}
     assert String.next_codepoint(<<255>>) == {<<255>>, ""}