Original package path env var when installing #2609
Description
Is your feature request related to a problem? Please describe.
I am working on an R package that uses some C++ files however other languages also use the C++ code so I would like to place it outside the R package root directory. I would like to use a configure script to copy these C++ files when I run devtools::install however this builds the package in a temp directory with no way (that I know of) to get the location of the source package in the configure script.
Describe the solution you'd like
I think it could be useful if a devtools env variable was set in the install function that had the absolute path of the source package. That way the configure script could use that variable if needed.
Describe alternatives you've considered
I am aware you could use quick = TRUE to install in place however installing in a temp directory would be preferable
Additional context
I am happy to make a PR with the change if this seems like a reasonable request.