RcppCore
C++11 as minimum supported standard
Meta-issue for discussion and to keep track of all the individual changes required to achieve this goal.
It may be helpful to define three classes of tasks and an ordering as DE sees it
- First order: establish C++11 as the baseline allowing variadic templates (and the 'can use C++11' define) to reduce to unconditional code which, as a major side effect and first order goal, leads to removal of all the pre-C++11 autogenerated code. Other cleanups below inst/include and in src/ happen basically as a side effect
- Second order, by a wide margin: cleanup below inst/ and removal of old helpers or illustrations which does not really affect anyone
- Third order, and possibly tied with or marginally ahead of the previous point: cleanup of R helper functins
Tasks
- [x] Clean up
inst/include/Rcpp/platform/compiler.h. Ancient tests and defines that are not required anymore. #1363 #1364 - [x] Review
HAS_VARIADIC_TEMPLATESchecks and remove carefully, also cleaning upinst/include/Rcpp/generatedstuff. (DE: I expect this to be one single careful PR) #1366 #1367 - [x] Review
RCPP_USING_CXX11checks and remove carefully. RInside uses this macro (see this search). Then, the definition could be removed. (DE: Thanks for the heads-up. I can take this.) #1369 - [x] Find remaining
if __cplusplus < 201103Land assess removal #1370 #1371 - [x] Review
RCPP_USING_UNORDERED_*checks and remove carefully. ReviewRCPP_UNORDERED_*types and just replace with the appropriatestd::unordered_*type. #1372 - [x] Remove branch in
inst/include/Rcpp/sugar/functions/sapply.h:41(see TODO there). (DE: Unsure about this one, lesser priority for me. To be determined...). (IU: Maybe the other way around: maybe we should just remove the first branch, the one that uses the std library. Then::Rcpp::traits::result_ofcould (or could not) be reimplemented based on the std library.) #1373 - [x] Reach out packages jiebaR, fwsim, ~~diveRsity~~ (removed from CRAN), which use
RCPP_UNORDERED_MAPandRCPP_UNORDERED_SET(see this search) in order to replace those uses too. We can deprecate these definitions and remove them in a future release. - [x] Maybe implement more variadic templates if any missing, then clean up remaining
inst/include/Rcpp/generatedstuff. - [x] Same for generated stuff under
inst/include/Rcpp/module. - [ ] Same for generated stuff under
inst/include/Rcpp/sugar/block. - [ ] Same for generated stuff under
inst/include/Rcpp/sugar/functions/mapply. - [ ] Clean up
R/RcppLdpath.R. Functions that have been deprecated for ages. Some internal functions could just be dropped (also theinst/discoveryscript). The exported ones require some revdep checking. (DE: Sure but low priority as it has not bitten anyone. We could also chase packages still doing 'Depends: Rcpp' but ... to what payoff?) - [ ] Clean up plugins in
R/Attributes.R. Particularly,cpp98,cpp0x, probablycpp11too. (DE: Unsure. There will be old code snippets hanging around that have this. Just as with old LdFlags() calls we could just make them null-ops) - [ ] Update vignettes accordingly.
@eddelbuettel Feel free to add/drop/edit/reorder above.
fwsim maintainer contacted here: https://lists.r-forge.r-project.org/pipermail/rcpp-devel/2025-March/010973.html
Yes trickier issue. "Eventually" we will make the same subsitution but we probably need to have a 'deprecated' period first where we warn. This is still a user-facing API.
I'm thrilled to see the new baseline move to C++11 tis like watching The Flintstones discover electricity. 😉
Let me know if I can help with anything! Looks like it's split with DE + IU and Kevin reviewing. Major props.
We're not there yet, but we are moving from wheels that are almost quadratic with their five sides to those with six. Almost a smooth ride now.
Kidding aside, many/most client packages have compilerd under C++11 or C++14 or C++17 (and some even C++20) for years. But the baseline is so safely aheard of C++98 that we can simply do the cleanup now. Fairly easily.