[Rcpp-devel] Optimization flag may be needed in Makevars.win for 4.9.2 toolchain

[Dirk Eddelbuettel]

On 25 August 2015 at 17:39, Avraham Adler wrote:
| I've been testing a GCC 4.9.2-based toolchain for Windows for the last
| week or so, and today fell afoul of the error uncovered here
| <https://stat.ethz.ch/pipermail/r-devel/2015-March/070814.html>. I've
| been passing different optimization flags, and Rcpp compiled properly
| under every one EXCEPT when a -march (ivybridge) flag was passed
| without an optimization flag. In that case, I received the
| "collect2.exe: error: ld returned 5 exit status" error as discussed on
| R-devel. Passing a -mtune flag without an -O flag did not cause an
| error.
| 
| Downloading the Rcpp source code and manually adding -O2 to Rcpp's
| Makevars.win, re-tar/gzipping it and installing the local version
| allowed Rcpp to compile properly.
| 
| I don't know if it is better to tell people to change their local
| Makevars under HOME/.R to pass -O2 or -O3 (that would probably be a
| call by you, Dirk, as you would know best if O3 would help or hinder),
| or if it is better to have Rcpp enforce it, but it should be noted
| somewhere once a 4.9.2-based Windows is eventually released.

CRAN disallows non-portable flags such as -march.

So yes, ~/.R/Makevars it is.

Dirk

-- 
http://dirk.eddelbuettel.com | @eddelbuettel | edd at debian.org