also fix using operators in function defines

lib/credo/check/readability/function_names.ex

@@ -23,6 +23,9 @@ defmodule Credo.Check.Readability.FunctionNames do
   @all_sigil_chars ~w(a A b B c C d D e E f F g G h H i I j J k K l L m M n N o O p P q Q r R s S t T u U v V w W x X y Y z Z)
   @all_sigil_atoms Enum.map(@all_sigil_chars, &:"sigil_#{&1}")
 
+  #all non-special-form operators
+  @all_nonspecial_operators ~W(! && ++ -- .. <> =~ @ |> || != !== * + - / <= == === > >= ||| &&& <<< >>> <<~ ~>> <~ ~> <~> <|> ^^^ ~~~)a
+
   use Credo.Check, base_priority: :high
 
   alias Credo.Code.Name
@@ -64,6 +67,12 @@ defmodule Credo.Check.Readability.FunctionNames do
       {ast, issues}
     end
 
+    # ignore non-special-form (overridable) operators
+    defp traverse({unquote(op), _meta, [{operator, _at_meta, _args} | _tail]} = ast, issues, _issue_meta)
+    when operator in @all_nonspecial_operators do
+      {ast, issues}
+    end
+
     defp traverse({unquote(op), _meta, arguments} = ast, issues, issue_meta) do
       {ast, issues_for_definition(arguments, issues, issue_meta)}
     end

test/credo/check/readability/function_names_test.exs

@@ -67,6 +67,22 @@ defmodule Credo.Check.Readability.FunctionNamesTest do
     |> refute_issues(@described_check)
   end
 
+  @tag :one
+  test "it should NOT report expected code (for operators) /6" do
+    """
+    defmacro @expr2
+    defmacro @expr do
+      # ...
+    end
+
+    def left ++ right do
+      # ++ code
+    end
+    """
+    |> to_source_file
+    |> refute_issues(@described_check)
+  end
+
   #
   # cases raising issues
   #