Do not reflect changes ignored due to :writable in returned struct

lib/ecto/repo/schema.ex

@@ -630,7 +630,7 @@ defmodule Ecto.Repo.Schema do
       case changes do
         %{^field => _change} ->
           handle_writable_violation(field, schema, action)
-          changes
+          Map.delete(changes, field)
         %{} ->
           changes
       end

lib/ecto/schema.ex

@@ -706,8 +706,7 @@ defmodule Ecto.Schema do
       attempts to modify a field that should not be modified according to it's `:writable` value.
       Must be one of `:nothing`, `:warn`, or `:raise`. If set to `:nothing`, the modification is
       silently ignored. If set to `:warn`, the modification is ignored and a warning is logged. If set
-      to `:raise`, an exception is raised and the operation is aborted. If `:writable` is set to `:always`,
-      `:on_writable_violation` must be set to `:nothing`. Defaults to `:nothing`.
+      to `:raise`, an exception is raised and the operation is aborted. Defaults to `:nothing`.
 
   """
   defmacro field(name, type \\ :string, opts \\ []) do

test/ecto/repo_test.exs

@@ -2439,6 +2439,20 @@ defmodule Ecto.RepoTest do
              ]
     end
 
+    test "update with on_writable_violation: :nothing/warn does not reflect ignored changes in returned struct" do
+      {:ok, %MySchemaWritable{always: 10, never: nil, insert: nil}} =
+        %MySchemaWritable{id: 1}
+        |> Ecto.Changeset.change(%{always: 10, never: 11, insert: 12})
+        |> TestRepo.update()
+
+      capture_log(fn ->
+        {:ok, %MySchemaWritableWarn{always: 10, never: nil, insert: nil}} =
+          %MySchemaWritableWarn{id: 1}
+          |> Ecto.Changeset.change(%{always: 10, never: 11, insert: 12})
+          |> TestRepo.update()
+      end)
+    end
+
     test "update with on_writable_violation: :nothing saves changes for writable: :always and ignores changes for writable: :insert/:never" do
       %MySchemaWritable{id: 1}
       |> Ecto.Changeset.change(%{always: 10, never: 11, insert: 12})
@@ -2513,6 +2527,20 @@ defmodule Ecto.RepoTest do
                    end
     end
 
+    test "insert with on_writable_violation: :nothing/warn does not reflect ignored changes in returned struct" do
+      {:ok, %MySchemaWritable{always: 10, never: nil, insert: 12}} =
+        %MySchemaWritable{id: 1}
+        |> Ecto.Changeset.change(%{always: 10, never: 11, insert: 12})
+        |> TestRepo.insert()
+
+      capture_log(fn ->
+        {:ok, %MySchemaWritableWarn{always: 10, never: nil, insert: 12}} =
+          %MySchemaWritableWarn{id: 2}
+          |> Ecto.Changeset.change(%{always: 10, never: 11, insert: 12})
+          |> TestRepo.insert()
+      end)
+    end
+
     test "insert with surfaced changes on_writable_violation: :nothing saves changes for writable: :always/:insert and ignores changes for writable: :never" do
       %MySchemaWritable{id: 1, always: 10, never: 11, insert: 12}
       |> Ecto.Changeset.change(%{})