I'm pretty sure this is from this R-devel commit:
https://github.com/r-devel/r-svn/commit/92c1d5de23c93576f55062e26d446feface07250
This turns on stricter boundary checking, specifically see
https://github.com/lme4/lme4/issues/794#issuecomment-2154948145
Arguably, accessing an element of a zero-length vector is at least
undefined behaviour, so you shouldn't be doing it ...
On 2024-07-08 6:46 p.m., Claborne, Daniel via R-package-devel wrote:
Seemingly starting with the most recent builds of R-devel, I�ve been getting
segfaults related to a piece of cpp code that indexes a zero-size
NumericVector. Essentially the same as this dummy example:
```
library(Rcpp)
sourceCpp(
code = '
#include<Rcpp.h>
using namespace Rcpp;
// [[Rcpp::export]]
NumericVector zeroindex() {
NumericVector zerosize(0);
Rcout << zerosize[0] << std::endl;
return zerosize;
}
'
)
zeroindex()
```
On R-release and on previous builds, this returns something like:
```
6.92674e-310
numeric(0)
```
But on current R-devel containers:
```
*** caught segfault ***
address 0x1, cause 'memory not mapped'
Traceback:
1: .Call(<pointer: 0x7fa9369c7930>)
2: zeroindex()
Possible actions:
1: abort (with core dump, if enabled)
2: normal R exit
3: exit R without saving workspace
4: exit R saving workspace
```
It was easy enough to write a catch for the zero-size vector, however I�m
wondering why the discrepancy between R-devel and previous versions?
Best,
-DMC
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