recommend importFrom in Rcpp FAQ (closes #1030)

Author: eddelbuettel

ChangeLog

@@ -1,3 +1,8 @@
+2019-12-05  Dirk Eddelbuettel  <[email protected]>
+
+	* vignettes/rmd/Rcpp-FAQ.Rmd (Rcpp): Add entry about "'dataptr' (or
+	'enterRNGScope') not provided by Rcpp" recommending proper importFrom
+
 2019-12-03  Dirk Eddelbuettel  <[email protected]>
 
 	* docker/ci/Dockerfile: Lighter builds as fewer Suggests:

vignettes/rmd/Rcpp-FAQ.Rmd

@@ -1754,3 +1754,10 @@ Rcpp Modules \citep{CRAN:Rcpp:Modules}.  Some more background on the linking
 requirement is [in this SO
 question](https://stackoverflow.com/questions/2424836/exceptions-are-not-caught-in-gcc-program).
 
+## My package fails with 'dataptr' (or 'enterRNGScope') not provided by Rcpp
+
+For your package, it is generally recommended to have both `Imports:` and
+`LinkingTo:` in the file `DESCRIPTION` combined with an explicit
+`importFrom("Rcpp", "evalCpp")` in the file `NAMESPACE`.  Doing so ensures
+that certain symbols are registered when your package is loaded by R, and
+that certain Rcpp functions are properly resolved.