From 3ae7f5fbd3f5b60960243ecfe216f232ccec61aa Mon Sep 17 00:00:00 2001
From: Matt Enlow <enlow@adobe.com>
Date: Mon, 18 Nov 2024 22:10:08 -0800
Subject: [PATCH] rewrite ranges

---
 lib/style/deprecations.ex        | 11 +++++++++++
 test/style/deprecations_test.exs | 28 ++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/lib/style/deprecations.ex b/lib/style/deprecations.ex
index 68050083..7b948d7b 100644
--- a/lib/style/deprecations.ex
+++ b/lib/style/deprecations.ex
@@ -17,6 +17,14 @@ defmodule Styler.Style.Deprecations do
 
   def run({node, meta}, ctx), do: {:cont, {style(node), meta}, ctx}
 
+  # rewrite patterns of `first..last = ...` to `first..last//_ = ...`
+  defp style({:=, m, [{:.., _, [_first, _last]} = range, rhs]}), do: {:=, m, [rewrite_range_match(range), rhs]}
+  defp style({:->, m, [[{:.., _, [_first, _last]} = range], rhs]}), do: {:->, m, [[rewrite_range_match(range)], rhs]}
+  defp style({:<-, m, [{:.., _, [_first, _last]} = range, rhs]}), do: {:<-, m, [rewrite_range_match(range), rhs]}
+
+  defp style({def, dm, [{x, xm, params} | rest]}) when def in ~w(def defp)a and is_list(params),
+    do: {def, dm, [{x, xm, Enum.map(params, &rewrite_range_match/1)} | rest]}
+
   # Logger.warn => Logger.warning
   # Started to emit warning after Elixir 1.15.0
   defp style({{:., dm, [{:__aliases__, am, [:Logger]}, :warn]}, funm, args}),
@@ -84,6 +92,9 @@ defmodule Styler.Style.Deprecations do
 
   defp style(node), do: node
 
+  defp rewrite_range_match({:.., dm, [first, {_, m, _} = last]}), do: {:"..//", dm, [first, last, {:_, m, nil}]}
+  defp rewrite_range_match(x), do: x
+
   defp add_step_to_date_range?(first, last) do
     with {:ok, f} <- extract_date_value(first),
          {:ok, l} <- extract_date_value(last),
diff --git a/test/style/deprecations_test.exs b/test/style/deprecations_test.exs
index 3d5e8ed9..7d93f452 100644
--- a/test/style/deprecations_test.exs
+++ b/test/style/deprecations_test.exs
@@ -33,6 +33,34 @@ defmodule Styler.Style.DeprecationsTest do
     )
   end
 
+  test "matching ranges" do
+    assert_style "first..last = range", "first..last//_ = range"
+    assert_style "^first..^last = range", "^first..^last//_ = range"
+    assert_style "first..last = x = y", "first..last//_ = x = y"
+    assert_style "y = first..last = x", "y = first..last//_ = x"
+
+    assert_style "def foo(x..y), do: :ok", "def foo(x..y//_), do: :ok"
+    assert_style "def foo(a, x..y = z), do: :ok", "def foo(a, x..y//_ = z), do: :ok"
+    assert_style "def foo(%{a: x..y = z}), do: :ok", "def foo(%{a: x..y//_ = z}), do: :ok"
+
+    assert_style "with a..b = c <- :ok, d..e <- :better, do: :ok", "with a..b//_ = c <- :ok, d..e//_ <- :better, do: :ok"
+
+    assert_style(
+      """
+      case x do
+        a..b = c -> :ok
+        d..e -> :better
+      end
+      """,
+      """
+      case x do
+        a..b//_ = c -> :ok
+        d..e//_ -> :better
+      end
+      """
+    )
+  end
+
   describe "1.16 deprecations" do
     @describetag skip: Version.match?(System.version(), "< 1.16.0-dev")