Control whether exceptions include the call and C++ stack with a macros

[romainfrancois]

Follow up to #663.

The idea is to have a general default for whether exceptions generated by Rcpp include the call stack or not.

#define RCPP_DEFAULT_INCLUDE_CALL false
#include <Rcpp.h>

// [[Rcpp::export]]
void Rcpp_exception(){
    throw Rcpp::exception("ouch");
}

// [[Rcpp::export]]
void eval_error(){
    Rcpp_eval(Rf_lang1(Rf_install("ouch")), R_EmptyEnv);
}

Adding the RCPP_DEFAULT_INCLUDE_CALL which by default is defined to true in Rcpp. When it is defined to false such as above, the default for include_call in Rcpp::exception is set to false, and the other exceptions, e.g. eval_error don't include the call and c++ stack.

> Rcpp::sourceCpp('inst/unitTests/cpp/Exceptions_nocall.cpp')
> Rcpp_exception()
Error: ouch
> eval_error_no_call()
Error: Evaluation error: could not find function "ouch".
> stop_no_call()
Error: ouch

Having this in place means that a package can globally decide not to include the call stack for all exceptions that are generated by Rcpp internal code, and also still be able to use stop(...) instead of throw Rcpp::exception(tfm::format(...).c_str(), include_call = false) which is I believe the only way available after #663.

The alternative to this PR would be to rework all other exception classes so that they also have the bool include_call setting.

This is not necessary as these other exceptions are mostly thrown by Rcpp itself and so there is no opportunity to set the include_call argument in their constructors.

[codecov-io]

Codecov Report

Merging #868 into master will decrease coverage by 0.22%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #868      +/-   ##
==========================================
- Coverage   90.21%   89.99%   -0.23%     
==========================================
  Files          70       71       +1     
  Lines        3261     3269       +8     
==========================================
  Hits         2942     2942              
- Misses        319      327       +8

Impacted Files	Coverage Δ
inst/include/Rcpp/exceptions.h	7.69% <ø> (ø)	⬆️
inst/include/Rcpp/protection/Shelter.h	0% <0%> (ø)

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[eddelbuettel]

If you could, please consider writing submissions and commit message without emojis.

[eddelbuettel]

Thanks for tieing it into #663. We'll take a look. At some point we may need a full grid documenting how stop() and friends can be called.

[romainfrancois]

if you could, please consider writing submissions and commit message without emojis.

I can do that, maybe this should be part of your contributions guidelines.

[eddelbuettel]

I edited these last week and decided against making it a requirement, but the language I added was milder under Coding Style:

It would be nice if the contributed code followed existing conventions for whitespace and indentation.

I am just asking you (as well as everybody else) rather gently to consider following existing style. Most people have no problem with that.

[romainfrancois]

I don't have a problem with that.

[eddelbuettel]

Excellent.

Now, as we're at style: We have one pending PR I'll likely merge soon. Do you want to rebase then, or would it be ok if I squash-merged this one? I prefer to keep the git graph tidy and narrow.

[romainfrancois]

Feel free to squash.

[eddelbuettel]

Worked like a charm in reverse depends, and now part of Rcpp 0.12.17.3 -- so thanks!

[romainfrancois]

Thanks.