The Rcpp team is trying to move towards defining STRICT_R_HEADERS by default. Please the issue ticket at RcppCore/Rcpp#1158 for motivation and history.
Your package uses PI (instead of the standard C define M_PI, or the newer Armadillo constant arma::datum::pi) and PI goes away when we set STRICT_R_HEADERS (as a #define in a header or source file, a -DSTRICT_R_HEADERS as a compiler flag, or as a #define in the Rcpp sources as we currently do). We plan to enable STRICT_R_HEADERS by the Jan 2022 release of Rcpp, and will likely offer you a define to suppress it. So if you really do not want the change you can prevent it -- see these lines in Rcpp for details:
https://github.com/RcppCore/Rcpp/blob/e79c70e76bc2a776d2d57287f7192dbdbcb292aa/inst/include/Rcpp/r/headers.h#L28-L38
As discussed in RcppCore/Rcpp#1158, this is not urgent, but we of course welcome relatively prompt resolution at CRAN so when we continue to test for this (at a likely montly pace) so we do not get false positives as we will continue to use the CRAN set of packages (as opposed to hand-curated set of upstream dev versions).
Many thanks for your help, and I hope you continue to find Rcpp helpful. Please don't hesitate to ask if you have any questions.
Dear Johan, dear eulerr team,
The Rcpp team is trying to move towards defining STRICT_R_HEADERS by default. Please the issue ticket at RcppCore/Rcpp#1158 for motivation and history.
Your package uses PI (instead of the standard C define M_PI, or the newer Armadillo constant arma::datum::pi) and PI goes away when we set STRICT_R_HEADERS (as a #define in a header or source file, a -DSTRICT_R_HEADERS as a compiler flag, or as a #define in the Rcpp sources as we currently do). We plan to enable STRICT_R_HEADERS by the Jan 2022 release of Rcpp, and will likely offer you a define to suppress it. So if you really do not want the change you can prevent it -- see these lines in Rcpp for details: https://github.com/RcppCore/Rcpp/blob/e79c70e76bc2a776d2d57287f7192dbdbcb292aa/inst/include/Rcpp/r/headers.h#L28-L38
As discussed in RcppCore/Rcpp#1158, this is not urgent, but we of course welcome relatively prompt resolution at CRAN so when we continue to test for this (at a likely montly pace) so we do not get false positives as we will continue to use the CRAN set of packages (as opposed to hand-curated set of upstream dev versions).
Many thanks for your help, and I hope you continue to find Rcpp helpful. Please don't hesitate to ask if you have any questions.