Rcpp function 打包时崩溃 RStudio

Question

I built a dummy Rcpp package using Rcpp.package.skeleton(myPackage) with a single function:

// [[Rcpp::export]]
double triple_balance(const double& balance) {

  if(R_IsNA(balance)) {
    stop("balance is NA, please provide a numeric value");
  } else {
     double result = balance*3;
    return result;
  }
}

In unit tests, I want to make sure that the function returns an error when a wrong input is passed, which it consistently does if I source it:

Rcpp::sourceCpp('src/triple_balance.cpp')
triple_balance("10")

Error in triple_balance("10"): Not compatible with requested type: [type=character; target=double].

However, if I Install and Restart the package, running triple_balance("10") crashes RStudio. I should add that the crash does not happen every time and it seems to depend on the initial state of the library, eg whether I installed previous versions of the package before, for example with or without const in the function definition.

What could explain such an inconsistent behaviour?

My sessionInfo :

> sessionInfo()
R version 3.6.0 (2019-04-26)
Platform: x86_64-redhat-linux-gnu (64-bit)
Running under: Red Hat Enterprise Linux Server 7.8 (Maipo)

Matrix products: default
BLAS/LAPACK: /usr/lib64/R/lib/libRblas.so

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C              
 [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8    
 [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8   
 [7] LC_PAPER=en_US.UTF-8       LC_NAME=C                 
 [9] LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] rcppDummy_1.0

loaded via a namespace (and not attached):
[1] compiler_3.6.0 tools_3.6.0    Rcpp_1.0.2     packrat_0.5.0 

Answer 1

In the use case

Rcpp::sourceCpp('src/triple_balance.cpp')
triple_balance("10")

the error is yours because while your interface is using double

double triple_balance(const double& balance)

that is not what you supply when you type "10" -- that is a character vector (or "string")!

You can catch that autoMAGICally with Rcpp if you use vector arguments:

// [[Rcpp::export]]
NumericVector triple_balance(const NumericVector & balance) {
    return balance * 3;
}

This now checks when the Rcpp data structure is instantiated:

R> triple_balance(10)
[1] 30
R> triple_balance(10L)
[1] 30
R> triple_balance("10")
Error in triple_balance("10") : 
  Not compatible with requested type: [type=character; target=double].
R> 

Best of all, it works automagically on vectors:

R> triple_balance(c(c(2,3), seq(10,30,by=10), log10(1:3)))
[1]  6.00000  9.00000 30.00000 60.00000 90.00000  0.00000  0.90309  1.43136
R> 

and also takes care of non-finite values:

R> triple_balance(c(10, NA, NaN, Inf, -Inf))
[1]   30   NA  NaN  Inf -Inf
R> 

Edit By the way, if I keep your version in the source file with an _orig appended, it works fine for me too (Ubuntu 20.04; current Rcpp)

R> triple_balance_orig("10")
Error in triple_balance_orig("10") : 
  Not compatible with requested type: [type=character; target=double].
R> packageVersion("Rcpp")
[1] ‘1.0.4.11’
R> 

That behavior is not new code, so I am a little surprised it crashes your RHEL installation.

Edit 2: For argument's sake, I also made it into a package, and it does not bring RStudio down either. I am running a very recent test version 1.4.390. (I have seen such crash on re-compilation of packages and errors, it can happen. It should not happen here.)

You could try your code in https://rstudio.cloud to quickly try a different enviroment.