[Rd] Compiler + stopifnot bug

[Iñaki Ucar]

Hi,

I found the following issue in r-devel (2019-01-02 r75945):

`foo<-` <- function(x, value) {
  bar(x) <- value * x
  x
}

`bar<-` <- function(x, value) {
  stopifnot(all(value / x == 1))
  x + value
}

`foo<-` <- compiler::cmpfun(`foo<-`)
`bar<-` <- compiler::cmpfun(`bar<-`)

x <- c(2, 2)
foo(x) <- 1
x # should be c(4, 4)
#> [1] 3 3

If the functions are not compiled or the stopifnot call is removed,
the snippet works correctly. So it seems that something is messing
around with the references to "value" when the call to stopifnot gets
compiled, and the wrong "value" is modified. Note also that if "x <-
2", then the result is correct, 4.

Regards,
-- 
Iñaki Úcar