fix JuliaLang#39982, remove cursor artifacts in REPL after JuliaLang#…

…40411 (JuliaLang#40452)

stdlib/REPL/src/LineEdit.jl

@@ -786,25 +786,30 @@ function edit_insert(s::PromptState, c::StringLike)
  after = options(s).auto_refresh_time_delay
  termbuf = terminal(s)
  w = width(termbuf)
- delayup = !eof(buf) || old_wait
  offset = s.ias.curs_row == 1 || s.indent < 0 ?
  sizeof(prompt_string(s.p.prompt)::String) : s.indent
  offset += position(buf) - beginofline(buf) # size of current line
- spinner = true
- if offset + textwidth(str) <= w
+ spinner = '\0'
+ delayup = !eof(buf) || old_wait
+ if offset + textwidth(str) <= w && !(after == 0 && delayup)
  # Avoid full update when appending characters to the end
  # and an update of curs_row isn't necessary (conservatively estimated)
  write(termbuf, str)
- spinner = false
+ spinner = ' ' # temporarily clear under the cursor
  elseif after == 0
  refresh_line(s)
  delayup = false
- else
+ else # render a spinner for each key press
+ if old_wait || length(str) != 1
+ spinner = spin_seq[mod1(position(buf) - w, length(spin_seq))]
+ else
+ spinner = str[end]
+ end
  delayup = true
  end
  if delayup
- if spinner
- write(termbuf, spin_seq[mod1(position(buf) - w, length(spin_seq))])
+ if spinner != '\0'
+ write(termbuf, spinner)
  cmove_left(termbuf)
  end
  s.refresh_wait = Timer(after) do t