[Rd] Intermittent crashes with inset `[<-` command

[Gabriel Becker]

Hi Brian,

I don't have a windows machine, but on a modern macbook pro I'm not able to
get this to crash in 3.5.1 or a very recent built-from-source R-devel.  I
increased the length of x by 2 orders of magnitude but that just made the
loop take a lot longer to successfully run in both R versions i tested.

So seems like there is some OS/machine dependency at work here (?).

Best,
~G

On Wed, Feb 27, 2019 at 12:01 AM Brian Montgomery via R-devel <
r-devel using r-project.org> wrote:

> The following code crashes after about 300 iterations on
> my x86_64-w64-mingw32 machine on R 3.5.2 --vanilla.
> Others have duplicated this (see
> https://github.com/tidyverse/magrittr/issues/190 if necessary), but I
> don't know how machine/OS-dependent it may be.
> If it doesn't crash for you, please try increasing the length of the x
> vector.
>
> Substituting the commented-out line for the one below it works correctly
> (prints out 1:1000 and ends normally) every time.
>
> x <- 1:200000
> y <- rep(letters[1:5], length(x) / 5L)
> for (i in 1:1000) {
>   # x[y == 'a'] <- x[y == 'b']
>   x <- `[<-`(x, y == 'a', x[y == 'b'])
>   cat(i, '')
> }
> cat('\n')
>
> The point of using this syntax is to make it work better with pipes, but
> the errors occur without pipes or magrittr.
>
> Thank you for your help!
>
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