[Rd] Cases of TAB-completion that hang Rterm

[Henrik Bengtsson]

FYI,

via a bug report of one of my packages, I discovered that the
following cases will hang Rterm when using TAB completion:

CASE #1:
Adding an empty default function for tail() causes Rterm on Windows to
hang if one press TAB at the prompt:

% Rterm -vanilla
> tail.default <- function(...) {}
> [PRESS TAB]
Error in specialOpLocs(text) :
  (list) object cannot be coerced to type 'double'

After this Rterm becomes completely unresponsive.  The same error
message will show up with Rgui, but R remains responsive.


CASE #2:
While troubleshooting the above, I discovered that if one does:

> debug(utils:::.guessTokenFromLine)
> [PRESS TAB]

or

> debug(utils:::.win32consoleCompletion)
> [PRESS TAB]

then Rterm hangs too (not Rgui).

This happens with R v2.13.0 patched (2011-05-30 r56020) and R v2.14.0
devel (2011-05-30 r56020) on Windows.

/Henrik