"Insert" Rcpp code chunk in RMarkdown uses "rcpp" not "Rcpp" which doesn't work

[DavisVaughan]

RStudio version 1.1.423, Mac

• File -> New File -> R Markdown...
• Insert -> Rcpp
• For me, the code chunk looks like:

```{rcpp}

```

Running something like the chunk below fails with /bin/sh: rcpp: command not found.

```{rcpp}
#include <Rcpp.h>
using namespace Rcpp;

// [[Rcpp::export]]
NumericVector timesTwo(NumericVector x) {
  return x * 2;
}
```

Changing it to Rcpp not rcpp works fine. I assume this has to do with the fact that Rcpp is used as the knit engine, not rcpp.

> names(knitr::knit_engines$get())
 [1] "awk"       "bash"      "coffee"    "gawk"      "groovy"    "haskell"   "lein"      "mysql"     "node"      "octave"    "perl"      "psql"     
[13] "Rscript"   "ruby"      "sas"       "scala"     "sed"       "sh"        "stata"     "zsh"       "highlight" "Rcpp"      "tikz"      "dot"      
[25] "c"         "fortran"   "fortran95" "asy"       "cat"       "asis"      "stan"      "block"     "block2"    "js"        "css"       "sql"      
[37] "go"        "python"    "julia"  

[DavisVaughan]

Potentially relevant line

rstudio/src/gwt/src/org/rstudio/studio/client/workbench/views/source/editors/text/TextEditingTarget.java

Line 4426 in 0506148

onInsertChunk("```{rcpp}\n\n```\n", 1, 0);