MAINT: Misc review comments

[HaoZeke]

where is this included from? I only see cpp11.cpp https://github.com/HaoZeke/fastMatMR/blob/main/src/from_file.cpp#L10
My IDE underlined this with red, but it might be fine, I am not familiar with cpp bindings in R packages

First noted here: ropensci/software-review#606 (comment).

[HaoZeke]

This is loaded in as part of the cpp11 package. It is found by R by using the following directive in the DESCRIPTION (as suggested by the documentation):

LinkingTo:
    cpp11

There really isn't a good way to get an IDE to be aware of the R installed package headers. cpp11.cpp is actually auto-generated :)