bug#13290: 24.2.91; [PATCH] Comint can stall emacs with non-trivial input senders

[Vitalie Spinu <spinuvit@gmail.com>]

  >> Glenn Morris <rgm@gnu.org>
  >> on Thu, 03 Jan 2013 01:49:03 -0500 wrote:

  > Vitalie Spinu wrote:
  >> The problem is that, occasionally, comint-input-sender might be a
  >> non-trivial function and could take care of process output itself.

  > Thanks for the report. Could you give an example of this happening in
  > practice?

Yes,  this was happening in ESS under some specific
conditions. Particularly when the user wants to evaluate the code
linewise, i.e. each line of code is echoed in the comint buffer, and
then the output is immediately inserted after that line.

This is implemented in comint-input-sender function, and it does nothing
else than just send input line by line and wait after each line for the
process output. Thus, after the execution of comint-input-sender there
was no process output left, and comint was waiting for nothing.

Cases like above, when both input and output should be manipulated, are
not easily implemented in comint-preoutput-filter-functions.

    Vitalie