fix_regression_on_modify_table

lib/ecto/adapters/postgres/connection.ex

@@ -1580,11 +1580,12 @@ if Code.ensure_loaded?(Postgrex) do
     defp column_change(table, {:modify, name, type, opts}) do
       column_type = column_type(type, opts)
       from_column_type = extract_column_type(opts[:from])
+      from_opts = extract_opts(opts)
 
       drop_reference_expr = drop_reference_expr(opts[:from], table, name)
       any_drop_ref? = drop_reference_expr != []
 
-      if column_type == column_type(from_column_type, opts) do
+      if column_type == column_type(from_column_type, from_opts) do
         modify_null = modify_null(name, Keyword.put(opts, :prefix_with_comma, any_drop_ref?))
         any_modify_null? = modify_null != []
 
@@ -1844,6 +1845,15 @@ if Code.ensure_loaded?(Postgrex) do
       [type, generated_expr(generated)]
     end
 
+    defp extract_opts(opts) do
+      with {:ok, from} <- Keyword.fetch(opts, :from),
+           {_type, from_opts} <- from do
+        from_opts
+      else
+        _ -> opts
+      end
+    end
+
     defp extract_column_type({type, _}) when is_atom(type), do: type
     defp extract_column_type(type) when is_atom(type), do: type
     defp extract_column_type(%Reference{type: type}), do: type

test/ecto/adapters/postgres_test.exs

@@ -2509,6 +2509,7 @@ defmodule Ecto.Adapters.PostgresTest do
           from: %Reference{table: :groups}},
          {:modify, :status, :string,
           [null: false, size: 100, from: {:integer, null: true, size: 50}]},
+         {:modify, :email, :string, [size: 512, from: {:string, size: 255}]},
          {:remove, :summary},
          {:remove, :body, :text, []},
          {:remove, :space_id, %Reference{table: :author}, []},
@@ -2546,6 +2547,7 @@ defmodule Ecto.Adapters.PostgresTest do
              ADD CONSTRAINT "posts_group_id_fkey" FOREIGN KEY ("group_id") REFERENCES "groups"("gid"),
              ALTER COLUMN "status" TYPE varchar(100),
              ALTER COLUMN "status" SET NOT NULL,
+             ALTER COLUMN "email" TYPE varchar(512),
              DROP COLUMN "summary",
              DROP COLUMN "body",
              DROP CONSTRAINT "posts_space_id_fkey",