[R] CRAN warnings from clang18

[david-cortes]

The last uploaded version of XGBoost at CRAN (1.7.6.1) started showing issues with the latest clang:

Found the following significant warnings:
  /usr/local/clang-trunk/bin/../include/c++/v1/__type_traits/result_of.h:32:1: warning: 'result_of<(lambda at src/objective/../common/stats.h:118:7) (unsigned long)>' is deprecated [-Wdeprecated-declarations]
  /usr/local/clang-trunk/bin/../include/c++/v1/__type_traits/result_of.h:32:1: warning: 'result_of<(lambda at src/objective/../common/stats.h:124:48) (unsigned long)>' is deprecated [-Wdeprecated-declarations]
  /usr/local/clang-trunk/bin/../include/c++/v1/__type_traits/result_of.h:32:1: warning: 'result_of<(lambda at src/objective/../common/linalg_op.h:66:44) (unsigned long)>' is deprecated [-Wdeprecated-declarations]
  /usr/local/clang-trunk/bin/../include/c++/v1/__type_traits/result_of.h:32:1: warning: 'result_of<(lambda at src/objective/../common/linalg_op.h:80:7) (unsigned long)>' is deprecated [-Wdeprecated-declarations]
  /usr/local/clang-trunk/bin/../include/c++/v1/__type_traits/result_of.h:32:1: warning: 'result_of<(lambda at src/objective/regression_obj.cu:245:45) &(unsigned long, const float &)>' is deprecated [-Wdeprecated-declarations]
  /usr/local/clang-trunk/bin/../include/c++/v1/__type_traits/result_of.h:32:1: warning: 'result_of<(lambda at src/objective/regression_obj.cu:696:45) &(unsigned long, const float &)>' is deprecated [-Wdeprecated-declarations]
  /usr/local/clang-trunk/bin/../include/c++/v1/__type_traits/result_of.h:32:1: warning: 'result_of<(lambda at src/objective/adaptive.cc:102:48) (unsigned long)>' is deprecated [-Wdeprecated-declarations]
  /usr/local/clang-trunk/bin/../include/c++/v1/__type_traits/result_of.h:32:1: warning: 'result_of<(lambda at src/objective/adaptive.cc:106:48) (unsigned long)>' is deprecated [-Wdeprecated-declarations]
  /usr/local/clang-trunk/bin/../include/c++/v1/__type_traits/result_of.h:32:1: warning: 'result_of<(lambda at src/data/./sparse_page_source.h:225:35) (const xgboost::data::ArrayAdapterBatch &)>' is deprecated [-Wdeprecated-declarations]
  /usr/local/clang-trunk/bin/../include/c++/v1/__type_traits/result_of.h:32:1: warning: 'result_of<(lambda at src/data/gradient_index.cc:81:44) (unsigned long)>' is deprecated [-Wdeprecated-declarations]
  /usr/local/clang-trunk/bin/../include/c++/v1/__type_traits/result_of.h:32:1: warning: 'result_of<(lambda at src/data/sparse_page_source.h:225:35) (const xgboost::data::ArrayAdapterBatch &)>' is deprecated [-Wdeprecated-declarations]
  /usr/local/clang-trunk/bin/../include/c++/v1/__type_traits/result_of.h:32:1: warning: 'result_of<(lambda at src/data/sparse_page_dmatrix.cc:66:16) (const xgboost::data::ArrayAdapterBatch &)>' is deprecated [-Wdeprecated-declarations]
  /usr/local/clang-trunk/bin/../include/c++/v1/__type_traits/result_of.h:32:1: warning: 'result_of<(lambda at src/data/sparse_page_dmatrix.cc:75:16) (const xgboost::data::ArrayAdapterBatch &)>' is deprecated [-Wdeprecated-declarations]
  /usr/local/clang-trunk/bin/../include/c++/v1/__type_traits/result_of.h:32:1: warning: 'result_of<(lambda at src/data/iterative_dmatrix.cc:100:39) (const xgboost::data::ArrayAdapterBatch &)>' is deprecated [-Wdeprecated-declarations]
  /usr/local/clang-trunk/bin/../include/c++/v1/__type_traits/result_of.h:32:1: warning: 'result_of<(lambda at src/data/iterative_dmatrix.cc:103:39) (const xgboost::data::ArrayAdapterBatch &)>' is deprecated [-Wdeprecated-declarations]
  /usr/local/clang-trunk/bin/../include/c++/v1/__type_traits/result_of.h:32:1: warning: 'result_of<(lambda at src/data/iterative_dmatrix.cc:109:39) (const xgboost::data::ArrayAdapterBatch &)>' is deprecated [-Wdeprecated-declarations]
  /usr/local/clang-trunk/bin/../include/c++/v1/__type_traits/result_of.h:32:1: warning: 'result_of<(lambda at src/data/iterative_dmatrix.cc:187:34) (const xgboost::data::ArrayAdapterBatch &)>' is deprecated [-Wdeprecated-declarations]
  /usr/local/clang-trunk/bin/../include/c++/v1/__type_traits/result_of.h:32:1: warning: 'result_of<(lambda at src/data/iterative_dmatrix.cc:211:32) (const xgboost::data::ArrayAdapterBatch &)>' is deprecated [-Wdeprecated-declarations]
  /usr/local/clang-trunk/bin/../include/c++/v1/__type_traits/result_of.h:32:1: warning: 'result_of<(lambda at src/data/iterative_dmatrix.cc:233:32) (const xgboost::data::ArrayAdapterBatch &)>' is deprecated [-Wdeprecated-declarations]
  /usr/local/clang-trunk/bin/../include/c++/v1/__type_traits/result_of.h:32:1: warning: 'result_of<(lambda at src/data/../common/../data/gradient_index.h:182:46) (unsigned long)>' is deprecated [-Wdeprecated-declarations]

They'll likely ask to fix these issues if they haven't already.

[trivialfis]

I haven't received any warning, but will submit a fix. Thank you for sharing!

[trivialfis]

Just got the warning today. Will work on it.

[jameslamb]

Over in {lightgbm} we also recently got some clang18 check warnings from CRAN.

This PR shows how we reproduced them in CI: microsoft/LightGBM#6265

Sharing in case you want to use that approach to help verify before submitting to CRAN, and maybe to catch such issues on PRs in the future.

[trivialfis]

Thank you for sharing! The CI script will be really helpful! I happened to have a machine with llvm development branch and reproduced the warnings. I submitted a fix a couple hours ago.

[trivialfis]

Should be fixed now.