[R-package] CRAN warnings on gcc-14

[jameslamb]

Description

I received an email from CRAN today:

Dear maintainer,

Please see the problems shown on
<https://cran.r-project.org/web/checks/check_results_lightgbm.html>.

Please correct before 2024-08-03 to safely retain your package on CRAN.

This is primarily about the compiler C++ warnings
shown in the fedora-gcc results.  These are from g++ 14.x
which was released a couple of months ago.

The CRAN Team

Reproducible example

See https://cran.r-project.org/web/checks/check_results_lightgbm.html.

Version: 4.4.0
Check: whether package can be installed
Result: WARN 
  Found the following significant warnings:
    io/dense_bin.hpp:617:27: warning: template-id not allowed for constructor in C++20 [-Wtemplate-id-cdtor]
    io/multi_val_dense_bin.hpp:346:26: warning: template-id not allowed for constructor in C++20 [-Wtemplate-id-cdtor]
    io/multi_val_sparse_bin.hpp:433:36: warning: template-id not allowed for constructor in C++20 [-Wtemplate-id-cdtor]
    io/sparse_bin.hpp:785:19: warning: template-id not allowed for constructor in C++20 [-Wtemplate-id-cdtor]
  See ‘/data/gannet/ripley/R/packages/tests-devel/lightgbm.Rcheck/00install.out’ for details.
  * used C++ compiler: ‘g++-14 (GCC) 14.1.0’

Environment info

v4.4.0 on CRAN

Additional Comments

If this wasn't so easy to fix, I might respond and say that this shouldn't be a problem because we explicitly request C++17 in the R package.

But it is pretty easy to fix, and in fact @hgminh95 has already done this in #6514.

Once that's merged, we should put up a v4.4.1 release (to CRAN and elsewhere). It'd also maybe be good to add a new CI job running with newer compilers if possible (maybe as part of #6514).

There is a gcc14 container image here: https://r-hub.github.io/containers/containers.html#gcc14

[jameslamb]

This appears to have been fixed by the v4.5.0 release (#6538).

See #6538 (comment) and the full check results at https://cran.r-project.org/web/checks/check_results_lightgbm.html.

Thanks very much to @hgminh95 for the help in #6514 🥳