Fix Macro.to_string/1 and ExUnit diffs for multi-letter sigils (#12627)

Author: wojtekmach

lib/elixir/lib/code/normalizer.ex

@@ -183,7 +183,7 @@ defmodule Code.Normalizer do
   defp do_normalize({sigil, meta, [{:<<>>, _, args} = string, modifiers]} = quoted, state)
        when is_list(args) and is_atom(sigil) do
     case Atom.to_string(sigil) do
-      <<"sigil_", _name>> ->
+      "sigil_" <> _ ->
         meta =
           meta
           |> patch_meta_line(state.parent_meta)

lib/elixir/lib/macro.ex

@@ -1560,11 +1560,18 @@ defmodule Macro do
     {left, right} = delimiter_pair(delimiter)
 
     case Atom.to_string(sigil) do
-      <<"sigil_", name>> when name >= ?A and name <= ?Z ->
-        args = sigil_args(args, fun)
-        {:<<>>, _, [binary]} = parts
-        formatted = <<?~, name, left::binary, binary::binary, right::binary, args::binary>>
-        {:ok, fun.(ast, formatted)}
+      <<"sigil_", first, rest::binary>> when first >= ?A and first <= ?Z ->
+        if upcase_letters?(rest) do
+          args = sigil_args(args, fun)
+          {:<<>>, _, [binary]} = parts
+
+          formatted =
+            <<?~, first, rest::binary, left::binary, binary::binary, right::binary, args::binary>>
+
+          {:ok, fun.(ast, formatted)}
+        else
+          :error
+        end
 
       <<"sigil_", name>> when name >= ?a and name <= ?z ->
         args = sigil_args(args, fun)
@@ -1580,6 +1587,15 @@ defmodule Macro do
     :error
   end
 
+  defp upcase_letters?(<<letter, rest::binary>>) when letter >= ?A and letter <= ?Z,
+    do: upcase_letters?(rest)
+
+  defp upcase_letters?(<<_>>),
+    do: false
+
+  defp upcase_letters?(<<>>),
+    do: true
+
   defp delimiter_pair("["), do: {"[", "]"}
   defp delimiter_pair("{"), do: {"{", "}"}
   defp delimiter_pair("("), do: {"(", ")"}

lib/elixir/src/elixir_tokenizer.erl

@@ -1536,7 +1536,7 @@ tokenize_sigil([$~ | T], Line, Column, Scope, Tokens) ->
   case tokenize_sigil_name(T, [], Line, Column + 1, Scope, Tokens) of
     {ok, Name, Rest, NewLine, NewColumn, NewScope, NewTokens} ->
       tokenize_sigil_contents(Rest, Name, NewLine, NewColumn, NewScope, NewTokens);
-    
+
     {error, Message, Token} ->
       Reason = {Line, Column, Message, Token},
       error(Reason, T, Scope, Tokens)

lib/elixir/test/elixir/macro_test.exs

@@ -569,6 +569,32 @@ defmodule MacroTest do
       assert Macro.to_string(576_460_752_303_423_455) == "576_460_752_303_423_455"
       assert Macro.to_string(-576_460_752_303_423_455) == "-576_460_752_303_423_455"
     end
+
+    defmodule HTML do
+      defstruct [:string]
+
+      defimpl Inspect do
+        def inspect(%{string: string}, _) do
+          "~HTML[#{string}]"
+        end
+      end
+    end
+
+    defmacro sigil_HTML({:<<>>, _, [string]}, []) do
+      Macro.escape(%HTML{string: string})
+    end
+
+    test "sigils" do
+      assert Macro.to_string(quote(do: ~HTML[hi])) == ~S/~HTML[hi]/
+
+      assert Macro.to_string(
+               quote do
+                 ~HTML"""
+                 hi
+                 """
+               end
+             ) == ~s[~HTML"""\nhi\n"""]
+    end
   end
 
   describe "to_string/2" do
@@ -660,6 +686,8 @@ defmodule MacroTest do
       assert macro_to_string(quote(do: ~S["'(123)'"])) == ~S/~S["'(123)'"]/
       assert macro_to_string(quote(do: ~s"#{"foo"}")) == ~S/~s"#{"foo"}"/
 
+      assert macro_to_string(quote(do: ~HTML[hi])) == ~S/~HTML[hi]/
+
       assert macro_to_string(
                quote do
                  ~s"""
@@ -699,6 +727,14 @@ defmodule MacroTest do
                  """
                end
              ) == ~s[~S"""\n"123"\n"""]
+
+      assert macro_to_string(
+               quote do
+                 ~HTML"""
+                 "123"
+                 """
+               end
+             ) == ~s[~HTML"""\n"123"\n"""]
     end
 
     test "tuple call" do

lib/ex_unit/test/ex_unit/diff_test.exs

@@ -26,6 +26,20 @@ defmodule ExUnit.DiffTest do
     end
   end
 
+  defmodule HTML do
+    defstruct [:string]
+
+    defimpl Inspect do
+      def inspect(%{string: string}, _) do
+        "~HTML[#{string}]"
+      end
+    end
+  end
+
+  defmacro sigil_HTML({:<<>>, _, [string]}, []) do
+    Macro.escape(%HTML{string: string})
+  end
+
   defmacrop one, do: 1
 
   defmacrop tuple(a, b) do
@@ -642,6 +656,12 @@ defmodule ExUnit.DiffTest do
       ~s/-~D[2017-10-02]-/,
       ~s/+"2017-10-01"+/
     )
+
+    refute_diff(
+      ~HTML[hi] = ~HTML[bye],
+      "-~HTML[hi]-",
+      "~HTML[+bye+]"
+    )
   end
 
   test "structs with missing keys on match" do
@@ -682,6 +702,12 @@ defmodule ExUnit.DiffTest do
       ~s/-~D[2017-10-02]-/,
       ~s/+"2017-10-01"+/
     )
+
+    refute_diff(
+      ~HTML[hi] == ~HTML[bye],
+      "~HTML[-hi-]",
+      "~HTML[+bye+]"
+    )
   end
 
   test "structs with same inspect but different inside match" do