Replace Rcpp dependency with cpp11

[pachadotdev]

Dear Posit Team,

I hope you are doing well.

I spent most of my night awake trying to fix this error that chased me for a few days: When I try to install "devtools" in the Niagara cluster, I get this error

> install.packages("Rcpp")
trying URL 'https://packagemanager.posit.co/cran/__linux__/jammy/latest/src/contrib/Rcpp_1.0.13.tar.gz'
Content type 'binary/octet-stream' length 3438451 bytes (3.3 MB)
==================================================
downloaded 3.3 MB

* installing *source* package ‘Rcpp’ ...
** package ‘Rcpp’ successfully unpacked and MD5 sums checked
** using staged installation
** libs
using C++ compiler: ‘Ubuntu clang version 19.1.3 (++20241031083547+ab51eccf88f5-1~exp1~20241031083703.58)’
clang++-19 -stdlib=libc++ -I"/opt/R/lib/R/include" -DNDEBUG -I../inst/include/  -I/usr/local/include    -fpic  -Wall -O3 -pedantic  -c api.cpp -o api.o
clang++-19 -stdlib=libc++ -I"/opt/R/lib/R/include" -DNDEBUG -I../inst/include/  -I/usr/local/include    -fpic  -Wall -O3 -pedantic  -c attributes.cpp -o attributes.o
clang++-19 -stdlib=libc++ -I"/opt/R/lib/R/include" -DNDEBUG -I../inst/include/  -I/usr/local/include    -fpic  -Wall -O3 -pedantic  -c barrier.cpp -o barrier.o
barrier.cpp:74:30: error: use of undeclared identifier 'VECTOR_PTR_RO'; did you mean
      'VECTOR_PTR'?
   74 |     return const_cast<SEXP*>(RCPP_VECTOR_PTR(x));                                                       /...
      |                              ^~~~~~~~~~~~~~~
      |                              VECTOR_PTR
../inst/include/Rcpp/r/compat.h:34:26: note: expanded from macro 'RCPP_VECTOR_PTR'
   34 | # define RCPP_VECTOR_PTR VECTOR_PTR_RO
      |                          ^
/opt/R/lib/R/include/Rinternals.h:290:15: note: 'VECTOR_PTR' declared here
  290 | NORET SEXP * (VECTOR_PTR)(SEXP x);
      |               ^
1 error generated.
make: *** [/opt/R/lib/R/etc/Makeconf:204: barrier.o] Error 1
ERROR: compilation failed for package ‘Rcpp’
* removing ‘/opt/R/lib/R/library/Rcpp’

The downloaded source packages are in
        ‘/tmp/RtmpYC6Btl/downloaded_packages’
Updating HTML index of packages in '.Library'
Making 'packages.html' ... done
Warning message:
In install.packages("Rcpp") :
  installation of package ‘Rcpp’ had non-zero exit status

I have tried using Docker images and building R from source.

After replicating Niagara's configuration, which is CentOS with clang 19, I realised I had to install Rcpp from GitHub (i.e., using "remotes"), which is something I cannot do in the cluster (my account has limited permissions and TI is very strict).

My solution is this PR with minimal changes, adhering to your coding style, and that also features unit tests.

I hope you can accept it.

Please let me know if I have to change anything and I will do it promply.

It is not your fault, but I was severely mistreated on Stackoverflow for asking about this. I spent days figuring out my own solution for this, and my PR fixed the issues in the Niagara cluster by replacing the "Rcpp" dependency by "cpp11". I am just a (former) Statistician doing a PhD in Political Science, not a computer expert.

Respectfully,
Mauricio Pacha Vargas Sepulveda

[lionel-]

I don't think we can omit testing Rcpp loading with pkgload.

I'm not sure why you couldn't install pkgload because of Rcpp, especially since it's only a "suggested" package, not "imported", so it's not a requirement for simple installation.

[DavisVaughan]

In Rcpp the guard for VECTOR_PTR_RO was previously set incorrectly. It has been fixed already in cran Rcpp of 1.0.13-1
RcppCore/Rcpp@3ae789b

[pachadotdev]

I don't think we can omit testing Rcpp loading with pkgload.

I'm not sure why you couldn't install pkgload because of Rcpp, especially since it's only a "suggested" package, not "imported", so it's not a requirement for simple installation.

ok, could it be possible to add my contribution in "parallel"?

[pachadotdev]

I don't think we can omit testing Rcpp loading with pkgload.

I'm not sure why you couldn't install pkgload because of Rcpp, especially since it's only a "suggested" package, not "imported", so it's not a requirement for simple installation.

Niagara (the server) is very particular. It uses something called R-batteries-included that runs on a modified CentOS. If anything works there, it works anywhere.