use exported R API when removing variables from environment

[kevinushey]

From a recent R-devel post:

Thanks for spotting this pattern. Using Rf_defineVar() this way to
delete a variable from package code is wrong because WRE does not
describe such behavior. That behavior has not been intended by the
implementation and as you observe, the variable will not be properly
deleted.

I found another pattern in another package (Rcpp, Rcpp11) which calls
directly the .Internal() function that deletes a variable, that is also
wrong, one should only use exported wrappers. The only legitimate way to
delete a variable in already released versions of R from C is to use
eval() to call R's rm()/remove(), but we will consider adding a C
function to the API to do this directly.

And the code:

Rcpp/inst/include/Rcpp/Environment.h

Lines 245 to 252 in d04eae8

	/* unless we want to copy all of do_remove,
	we have to go back to R to do this operation */
	SEXP internalSym = Rf_install( ".Internal" );
	SEXP removeSym = Rf_install( "remove" );
	Shield<SEXP> call( Rf_lang2(internalSym,
	Rf_lang4(removeSym, Rf_mkString(name.c_str()), Storage::get__(), Rf_ScalarLogical( FALSE ))
	) );
	Rcpp_fast_eval( call, R_GlobalEnv ) ;

We're already calling back to R; might as well use the official function base::rm.

[eddelbuettel]

Thanks. I follow r-devel pretty closely but missed this. [ Turns out I was behind on that folder. Busy day. ] Well and we know how the OP "really" feels about Rcpp, don't we ;-)

[github-actions]

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