[ruby/reline] Fix line rendering when newline is added at the end of the buffer

https://github.com/ruby/reline/commit/7d61b3df9a

lib/reline/line_editor.rb

@@ -468,7 +468,7 @@ class Reline::LineEditor
     rendered = false
     if @add_newline_to_end_of_buffer
       clear_dialog_with_content
-      rerender_added_newline(prompt, prompt_width)
+      rerender_added_newline(prompt, prompt_width, prompt_list)
       @add_newline_to_end_of_buffer = false
     else
       if @just_cursor_moving and not @rerender_all
@@ -969,11 +969,19 @@ class Reline::LineEditor
     end
   end
 
-  private def rerender_added_newline(prompt, prompt_width)
-    scroll_down(1)
+  private def rerender_added_newline(prompt, prompt_width, prompt_list)
     @buffer_of_lines[@previous_line_index] = @line
     @line = @buffer_of_lines[@line_index]
-    unless @in_pasting
+    @previous_line_index = nil
+    if @in_pasting
+      scroll_down(1)
+    else
+      lines = whole_lines
+      prev_line_prompt = @prompt_proc ? prompt_list[@line_index - 1] : prompt
+      prev_line_prompt_width = @prompt_proc ? calculate_width(prev_line_prompt, true) : prompt_width
+      prev_line = modify_lines(lines)[@line_index - 1]
+      render_partial(prev_line_prompt, prev_line_prompt_width, prev_line, @first_line_started_from + @started_from, with_control: false)
+      scroll_down(1)
       render_partial(prompt, prompt_width, @line, @first_line_started_from + @started_from + 1, with_control: false)
     end
     @cursor = @cursor_max = calculate_width(@line)
@@ -982,7 +990,6 @@ class Reline::LineEditor
     @highest_in_this = calculate_height_by_width(prompt_width + @cursor_max)
     @first_line_started_from += @started_from + 1
     @started_from = calculate_height_by_width(prompt_width + @cursor) - 1
-    @previous_line_index = nil
   end
 
   def just_move_cursor

test/reline/yamatanooroti/test_rendering.rb

@@ -690,6 +690,19 @@ begin
       EOC
     end
 
+    def test_newline_after_wrong_indent
+      start_terminal(5, 30, %W{ruby -I#{@pwd}/lib #{@pwd}/test/reline/yamatanooroti/multiline_repl --auto-indent}, startup_message: 'Multiline REPL.')
+      write "if 1\n    aa"
+      write "\n"
+      close
+      assert_screen(<<~EOC)
+        Multiline REPL.
+        prompt> if 1
+        prompt>   aa
+        prompt>
+      EOC
+    end
+
     def test_suppress_auto_indent_just_after_pasted
       start_terminal(5, 30, %W{ruby -I#{@pwd}/lib #{@pwd}/test/reline/yamatanooroti/multiline_repl --auto-indent}, startup_message: 'Multiline REPL.')
       write("def hoge\n  [[\n      3]]\ned")