wrap_logical warning message when loading objects created in R 3.6 in an R 3.5 session

Hi,

I am experiencing a warning message when I load a large R object
created in an R 3.6 session in R 3.5.* , as follows:

```
Warning message:
In load(?GDSCv2.RData?) :
 cannot unserialize ALTVEC object of class ?wrap_logical? from package
?base?; returning length zero vector
```
Of relevant information may be that the large R object (a data
structure defined in my Bioconductor package PharmacoGx), was in part
created including data frames which were cast from data.tables. I
noticed that the ALTVEC class had caused some errors previously in the
data.table package.

I have two questions:
1. Should I be concerned about this warning? I cannot seem to find
what effect it has on the data loaded.
2. Could you point me towards narrowing down the cause of this issue?
Ideally, everyone would upgrade R promptly, but even our own
institute's HPC cluster is still on 3.5, and the warning does not
inspire confidence for some of the less technical members of our group
who are using the datasets.

Petr Smirnov
PhD Candidate,
Benjamin Haibe-Kains Lab
Princess Margaret Cancer Centre
University of Toronto

psmirnov2000 at gmail.com