[Rd] use of the tcltk package crashes R 4.0.1 for Windows

[Jeroen Ooms]

On Sun, Jun 7, 2020 at 3:13 AM Fox, John <jfox using mcmaster.ca> wrote:
>
> Hi,
>
> The following code, from the examples in ?TkWidgets , immediately crashes R 4.0.1 for Windows:
>
> --------------------- snip --------------------
> library("tcltk")
> tt <- tktoplevel()
> label.widget <- tklabel(tt, text = "Hello, World!")
> button.widget <- tkbutton(tt, text = "Push",
>          command = function()cat("OW!\n"))
> tkpack(label.widget, button.widget) # geometry manager
> --------------------- snip --------------------


I can reproduce this. The backtrace shows the crash happens in
dotTclObjv  [/src/library/tcltk/src/tcltk.c using 243 ]. This looks like a
bug that was introduced by commit 78408/78409 about a month ago. I
think the problem is that this commit changes 'calloc' to 'Calloc'
without changing the corresponding 'free' to 'Free'.

This has nothing to do with the Windows build or installation. Nothing
has changed in the windows build procedure between 4.0.0 and 4.0.1.