Deprecate single quites in quoted atoms and calls, refs #13958

lib/elixir/src/elixir_tokenizer.erl

@@ -488,7 +488,15 @@ tokenize([T | Rest], Line, Column, Scope, Tokens) when ?pipe_op(T) ->
 
 % Non-operator Atoms
 
-tokenize([$:, H | T] = Original, Line, Column, Scope, Tokens) when ?is_quote(H) ->
+tokenize([$:, H | T] = Original, Line, Column, BaseScope, Tokens) when ?is_quote(H) ->
+  Scope = case H == $' of
+    true ->
+      prepend_warning(Line, Column, "single quotes around atoms are deprecated. Use double quotes instead", BaseScope);
+
+    false ->
+      BaseScope
+  end,
+
   case elixir_interpolation:extract(Line, Column + 2, Scope, true, T, H) of
     {NewLine, NewColumn, Parts, Rest, InterScope} ->
       NewScope = case is_unnecessary_quote(Parts, InterScope) of
@@ -896,7 +904,15 @@ handle_dot([$., $( | Rest], Line, Column, DotInfo, Scope, Tokens) ->
   TokensSoFar = add_token_with_eol({dot_call_op, DotInfo, '.'}, Tokens),
   tokenize([$( | Rest], Line, Column, Scope, TokensSoFar);
 
-handle_dot([$., H | T] = Original, Line, Column, DotInfo, Scope, Tokens) when ?is_quote(H) ->
+handle_dot([$., H | T] = Original, Line, Column, DotInfo, BaseScope, Tokens) when ?is_quote(H) ->
+  Scope = case H == $' of
+    true ->
+      prepend_warning(Line, Column, "single quotes around calls are deprecated. Use double quotes instead", BaseScope);
+
+    false ->
+      BaseScope
+  end,
+
   case elixir_interpolation:extract(Line, Column + 1, Scope, true, T, H) of
     {NewLine, NewColumn, [Part], Rest, InterScope} when is_list(Part) ->
       NewScope = case is_unnecessary_quote([Part], InterScope) of

lib/elixir/test/elixir/kernel/warning_test.exs

@@ -201,6 +201,42 @@ defmodule Kernel.WarningTest do
     end
   end
 
+  describe "deprecated single quotes in atoms" do
+    test "warns for single quotes in atoms" do
+      assert_warn_eval(
+        [
+          "nofile:1:1",
+          "single quotes around atoms are deprecated. Use double quotes instead"
+        ],
+        ~s/:'a+b'/
+      )
+    end
+
+    test "warns twice for single and unnecessary atom quotes" do
+      assert_warn_eval(
+        [
+          "nofile:1:1",
+          "single quotes around atoms are deprecated. Use double quotes instead",
+          "nofile:1:1",
+          "found quoted atom \"ab\" but the quotes are not required"
+        ],
+        ~s/:'ab'/
+      )
+    end
+
+    test "warns twice for single and unnecessary call quotes" do
+      assert_warn_eval(
+        [
+          "nofile:1:9",
+          "single quotes around calls are deprecated. Use double quotes instead",
+          "nofile:1:9",
+          "found quoted call \"length\" but the quotes are not required"
+        ],
+        ~s/[Kernel.'length'([])]/
+      )
+    end
+  end
+
   test "warns on :: as atom" do
     assert_warn_eval(
       [

lib/elixir/test/erlang/atom_test.erl

@@ -17,7 +17,7 @@ atom_with_punctuation_test() ->
   {'...', []} = eval(":...").
 
 atom_quoted_call_test() ->
-  {3, []} = eval("Kernel.'+'(1, 2)").
+  {3, []} = eval("Kernel.\"+\"(1, 2)").
 
 kv_with_quotes_test() ->
   {'foo bar', []} = eval(":atom_test.kv(\"foo bar\": nil)").
@@ -29,7 +29,6 @@ kv_with_interpolation_test() ->
 
 quoted_atom_test() ->
   {'+', []} = eval(":\"+\""),
-  {'+', []} = eval(":'+'"),
   {'foo bar', []} = eval(":\"foo bar\"").
 
 atom_with_interpolation_test() ->