Fix deprecated Dict, HashDict, and HashSet calls

Resolve the deprecated dictionary branches against Elixir.Dict rather than
the absent Erlang module Dict.
Use the fully qualified module names in HashDict and HashSet protocols too.

Closes #15987.

Assisted-by: Codex:GPT-6

Author: leostera

lib/elixir/lib/enum.ex

@@ -1446,7 +1446,7 @@ defmodule Enum do
     )
 
     # Avoid warnings about Dict
-    dict_module = String.to_unsafe_atom("Dict")
+    dict_module = String.to_unsafe_atom("Elixir.Dict")
 
     reduce(reverse(enumerable), dict, fn entry, categories ->
       dict_module.update(categories, fun.(entry), [entry], &[entry | &1])

lib/elixir/lib/hash_dict.ex

@@ -265,13 +265,13 @@ defimpl Enumerable, for: HashDict do
 
   def reduce(dict, acc, fun) do
     # Avoid warnings about HashDict being deprecated.
-    module = String.to_unsafe_atom("HashDict")
+    module = String.to_unsafe_atom("Elixir.HashDict")
     module.reduce(dict, acc, fun)
   end
 
   def member?(dict, {key, value}) do
     # Avoid warnings about HashDict being deprecated.
-    module = String.to_unsafe_atom("HashDict")
+    module = String.to_unsafe_atom("Elixir.HashDict")
     {:ok, match?({:ok, ^value}, module.fetch(dict, key))}
   end
 
@@ -281,7 +281,7 @@ defimpl Enumerable, for: HashDict do
 
   def count(dict) do
     # Avoid warnings about HashDict being deprecated.
-    module = String.to_unsafe_atom("HashDict")
+    module = String.to_unsafe_atom("Elixir.HashDict")
     {:ok, module.size(dict)}
   end
 
@@ -296,7 +296,7 @@ defimpl Collectable, for: HashDict do
 
   def into(original) do
     # Avoid warnings about HashDict being deprecated.
-    module = String.to_unsafe_atom("HashDict")
+    module = String.to_unsafe_atom("Elixir.HashDict")
 
     collector_fun = fn
       dict, {:cont, {key, value}} -> module.put(dict, key, value)
@@ -315,7 +315,7 @@ defimpl Inspect, for: HashDict do
 
   def inspect(dict, opts) do
     # Avoid warnings about HashDict being deprecated.
-    module = String.to_unsafe_atom("HashDict")
+    module = String.to_unsafe_atom("Elixir.HashDict")
     concat(["#HashDict<", Inspect.List.inspect(module.to_list(dict), opts), ">"])
   end
 end

lib/elixir/lib/hash_set.ex

@@ -279,19 +279,19 @@ defimpl Enumerable, for: HashSet do
 
   def reduce(set, acc, fun) do
     # Avoid warnings about HashSet being deprecated.
-    module = String.to_unsafe_atom("HashSet")
+    module = String.to_unsafe_atom("Elixir.HashSet")
     module.reduce(set, acc, fun)
   end
 
   def member?(set, term) do
     # Avoid warnings about HashSet being deprecated.
-    module = String.to_unsafe_atom("HashSet")
+    module = String.to_unsafe_atom("Elixir.HashSet")
     {:ok, module.member?(set, term)}
   end
 
   def count(set) do
     # Avoid warnings about HashSet being deprecated.
-    module = String.to_unsafe_atom("HashSet")
+    module = String.to_unsafe_atom("Elixir.HashSet")
     {:ok, module.size(set)}
   end
 
@@ -306,7 +306,7 @@ defimpl Collectable, for: HashSet do
 
   def into(original) do
     # Avoid warnings about HashSet being deprecated.
-    module = String.to_unsafe_atom("HashSet")
+    module = String.to_unsafe_atom("Elixir.HashSet")
 
     collector_fun = fn
       set, {:cont, term} -> module.put(set, term)
@@ -325,7 +325,7 @@ defimpl Inspect, for: HashSet do
 
   def inspect(set, opts) do
     # Avoid warnings about HashSet being deprecated.
-    module = String.to_unsafe_atom("HashSet")
+    module = String.to_unsafe_atom("Elixir.HashSet")
     concat(["#HashSet<", Inspect.List.inspect(module.to_list(set), opts), ">"])
   end
 end

lib/elixir/lib/uri.ex

@@ -254,7 +254,7 @@ defmodule URI do
 
       {{key, value}, rest} ->
         # Avoid warnings about Dict being deprecated
-        dict_module = String.to_unsafe_atom("Dict")
+        dict_module = String.to_unsafe_atom("Elixir.Dict")
         decode_query_into_dict(rest, dict_module.put(dict, key, value), encoding)
     end
   end