I have the same issue. After reading through several posts,
I tried the following and it still didn't work,
(1) Updated XCode
(2) Tried install.packages("Rcpp", dependencies = TRUE) and install.packages("Rcpp", dependencies = FALSE)
(3) install.packages("tidyverse", repo = 'https://mac.R-project.org')
(4) Uninstalled and reinstalled R and RStudio
(5) Updated all packages
None of these worked for me. The only thing that worked is what was recommended here by @andresrcs. Although it is not clear to me what this means. After installing Rcpp successfully, I was able to install tidyverse.
I wonder if others have had this issue and what is the reason behind it. If I understand correctly, this is an issue for Mac users.
NOTE: Only Rcpp seems to be the issue. All other packages and updates work well. If I try to update it after installation, that also doesn't work.