Fix charlist formatting issue on '\"' (#13364)

Author: sabiwara

lib/elixir/lib/code/formatter.ex

@@ -6,7 +6,8 @@ defmodule Code.Formatter do
   @double_heredoc "\"\"\""
   @single_quote "'"
   @single_heredoc "'''"
-  @sigil_c "~c\""
+  @sigil_c_double "~c\""
+  @sigil_c_single "~c'"
   @sigil_c_heredoc "~c\"\"\""
   @newlines 2
   @min_line 0
@@ -300,7 +301,7 @@ defmodule Code.Formatter do
         remote_to_algebra(quoted, context, state)
 
       meta[:delimiter] == ~s['''] ->
-        {opener, quotes} = get_charlist_quotes(true, state)
+        {opener, quotes} = get_charlist_quotes(:heredoc, state)
 
         {doc, state} =
           entries
@@ -310,7 +311,7 @@ defmodule Code.Formatter do
         {force_unfit(doc), state}
 
       true ->
-        {opener, quotes} = get_charlist_quotes(false, state)
+        {opener, quotes} = get_charlist_quotes({:regular, entries}, state)
         list_interpolation_to_algebra(entries, quotes, state, opener, quotes)
     end
   end
@@ -369,13 +370,14 @@ defmodule Code.Formatter do
   defp quoted_to_algebra({:__block__, meta, [list]}, _context, state) when is_list(list) do
     case meta[:delimiter] do
       ~s['''] ->
-        {opener, quotes} = get_charlist_quotes(true, state)
+        {opener, quotes} = get_charlist_quotes(:heredoc, state)
         string = list |> List.to_string() |> escape_heredoc(quotes)
         {opener |> concat(string) |> concat(quotes) |> force_unfit(), state}
 
       ~s['] ->
-        {opener, quotes} = get_charlist_quotes(false, state)
-        string = list |> List.to_string() |> escape_string(quotes)
+        string = list |> List.to_string()
+        {opener, quotes} = get_charlist_quotes({:regular, [string]}, state)
+        string = escape_string(string, quotes)
         {opener |> concat(string) |> concat(quotes), state}
 
       _other ->
@@ -2422,19 +2424,23 @@ defmodule Code.Formatter do
     {left, right}
   end
 
-  defp get_charlist_quotes(_heredoc = false, state) do
+  defp get_charlist_quotes(:heredoc, state) do
     if state.normalize_charlists_as_sigils do
-      {@sigil_c, @double_quote}
+      {@sigil_c_heredoc, @double_heredoc}
     else
-      {@single_quote, @single_quote}
+      {@single_heredoc, @single_heredoc}
     end
   end
 
-  defp get_charlist_quotes(_heredoc = true, state) do
-    if state.normalize_charlists_as_sigils do
-      {@sigil_c_heredoc, @double_heredoc}
-    else
-      {@single_heredoc, @single_heredoc}
+  defp get_charlist_quotes({:regular, chunks}, state) do
+    cond do
+      !state.normalize_charlists_as_sigils -> {@single_quote, @single_quote}
+      Enum.any?(chunks, &has_double_quote?/1) -> {@sigil_c_single, @single_quote}
+      true -> {@sigil_c_double, @double_quote}
     end
   end
+
+  defp has_double_quote?(chunk) do
+    is_binary(chunk) and chunk =~ @double_quote
+  end
 end

lib/elixir/test/elixir/code_formatter/literals_test.exs

@@ -210,10 +210,15 @@ defmodule Code.Formatter.LiteralsTest do
     test "with escapes" do
       assert_format ~S['f\a\b\ro'], ~S[~c"f\a\b\ro"]
       assert_format ~S['single \' quote'], ~S[~c"single ' quote"]
-      assert_format ~S['double " quote'], ~S[~c"double \" quote"]
+      assert_format ~S['double " quote'], ~S[~c'double " quote']
+      assert_format ~S['escaped \" quote'], ~S[~c'escaped \" quote']
+      assert_format ~S['\\"'], ~S[~c'\\"']
 
       assert_same ~S['f\a\b\ro'], @keep_charlists
       assert_same ~S['single \' quote'], @keep_charlists
+      assert_same ~S['double " quote'], @keep_charlists
+      assert_same ~S['escaped \" quote'], @keep_charlists
+      assert_same ~S['\\"'], @keep_charlists
     end
 
     test "keeps literal new lines" do
@@ -235,13 +240,15 @@ defmodule Code.Formatter.LiteralsTest do
 
     test "with interpolation" do
       assert_format ~S['one #{2} three'], ~S[~c"one #{2} three"]
+      assert_format ~S['#{1}\n \\ " \"'], ~S[~c'#{1}\n \\ " \"']
 
       assert_same ~S['one #{2} three'], @keep_charlists
+      assert_same ~S['#{1}\n \\ " \"'], @keep_charlists
     end
 
     test "with escape and interpolation" do
       assert_format ~S['one\n\'#{2}\'\nthree'], ~S[~c"one\n'#{2}'\nthree"]
-      assert_format ~S['one\n"#{2}"\nthree'], ~S[~c"one\n\"#{2}\"\nthree"]
+      assert_format ~S['one\n"#{2}"\nthree'], ~S[~c'one\n"#{2}"\nthree']
 
       assert_same ~S['one\n\'#{2}\'\nthree'], @keep_charlists
     end