R devel - Mar 2020 - help with rchk warnings on Rf_eval(Rf_lang2(...))

> Shield<SEXP> res(Rcpp_fast_eval(Rf_lang2(asEnvironmentSym, x),
R_GlobalEnv));
The call should be protected before evaluation though. So more like:

Shield<SEXP> call(Rf_lang2(asEnvironmentSym, x));
return Rcpp_fast_eval(call, R_GlobalEnv);

Best,
Lionel

On 3/23/20, Dirk Eddelbuettel <edd at debian.org>
wrote:
>
>
> On 23 March 2020 at 17:07, Ben Bolker wrote:
> | Or is there a way I can use Shield() since this an Rcpp-based project
> | anyway?
>
> Yes you can, and I would recommend it.
>
> Example from Rcpp itself, file Environment.h:
>
>   Shield<SEXP> res(Rcpp_fast_eval(Rf_lang2(asEnvironmentSym, x),
> R_GlobalEnv));
>
> For Rcpp_fast_eval, you may still need to #define RCPP_USE_UNWIND_PROTECT
> before including Rcpp.h; as I recall we were seeing too many side effects
> in
> other packages when globally enabling it.  Or you can play it safe and
> simply
> use Rcpp_eval.
>
> This really was more of a rcpp-devel question.
>
> Dirk
>
> --
> http://dirk.eddelbuettel.com | @eddelbuettel | edd at debian.org
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>

On 24 March 2020 at 11:39, Lionel Henry wrote:
| > Shield<SEXP> res(Rcpp_fast_eval(Rf_lang2(asEnvironmentSym, x),
R_GlobalEnv));
| 
| The call should be protected before evaluation though. So more like:
| 
| Shield<SEXP> call(Rf_lang2(asEnvironmentSym, x));
| return Rcpp_fast_eval(call, R_GlobalEnv);

Good catch.

And recursive grep for Rf_lang2 in the Rcpp sources tree suggests this is as the
common pattern in all other instances.

Dirk

edd at rob:~/git/rcpp(master)$ ag Rf_lang2 inst/include/
inst/include/Rcpp/exceptions.h
360:        Rcpp::Shield<SEXP>
simpleErrorExpr(Rf_lang2(::Rf_install("simpleError"), txt));
365:        Rcpp::Shield<SEXP> simpleErrorExpr(
Rf_lang2(::Rf_install("simpleError"), tryError ));
388:    Rcpp::Shield<SEXP> expr( Rf_lang2( stop_sym , condition ) ) ;
395:    Rcpp::Shield<SEXP> expr( Rf_lang2( stop_sym , condition ) ) ;

inst/include/Rcpp/Reference.h
62:            Shield<SEXP> call(Rf_lang2(newSym, str));

inst/include/Rcpp/api/meat/Rcpp_eval.h
99:            Shield<SEXP>
conditionMessageCall(::Rf_lang2(::Rf_install("conditionMessage"),
res));

inst/include/Rcpp/macros/macros.h
69:       SEXP expr = PROTECT( Rf_lang2( stop_sym , rcpp_output_condition ) ) ; 
\

inst/include/Rcpp/Environment.h
36:                Shield<SEXP>
res(Rcpp_fast_eval(Rf_lang2(asEnvironmentSym, x), R_GlobalEnv));
250:                    Shield<SEXP> call(Rf_lang2(internalSym,
Rf_lang4(removeSym, str, Storage::get__(), Rf_ScalarLogical(FALSE))));
376:                Shield<SEXP> call( Rf_lang2(getNamespaceSym,
package_str) );

inst/include/Rcpp/r_cast.h
34:                Shield<SEXP> call(Rf_lang2(funSym, x));
117:                    Shield<SEXP> call( Rf_lang2( Rf_install(
"as.character" ), x ) );

inst/include/Rcpp/Module.h
456:    Shield<SEXP> __load_module_call__( Rf_lang2( GET_MODULE_SYM,
_rcpp_module_boot_##NAME() ) ); \

inst/include/Rcpp/lang.h
26:#define Rcpp_lang2 Rf_lang2
edd at rob:~/git/rcpp(master)$ 

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

On 24 March 2020 at 07:19, Dirk Eddelbuettel wrote:
| On 24 March 2020 at 11:39, Lionel Henry wrote:
| | > Shield<SEXP> res(Rcpp_fast_eval(Rf_lang2(asEnvironmentSym, x),
R_GlobalEnv));
| | 
| | The call should be protected before evaluation though. So more like:
| | 
| | Shield<SEXP> call(Rf_lang2(asEnvironmentSym, x));
| | return Rcpp_fast_eval(call, R_GlobalEnv);
| 
| Good catch.

Fixed in https://github.com/RcppCore/Rcpp/pull/1059 along with another
instance from further down in the same file.

Thanks to Romain and Lionel for spotting this.

Dirk

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