I don't know how to form the ${RSTUDIO_GIT_REVISION_HASH} string. And I'm not sure these instructions are up to date.
Thanks.
PS FYI I want to build RStudio from source because I've run into a bug that's hard to replicate. This bug turned up fairly recently, so I want to see if using an older version of RStudio fixes it.
If you just want to see if an old version fixes your bug, you might not need the source code, rather the installer. You can find those here: Older Versions - Posit Documentation
Now if you click on "Installers" for one of these versions, say 2021.09.2 Ghost Orchid, you find the installers for each system. If you click "details" on the right, that opens a table, where the bottom entry is the "Commit Hash", for example for Ghost Orchid:
The fc9e21... is the GIT REVISION (=commit) HASH, and by clicking the link you can get to the state of the source code by the time that version was released. You can change commit to tree in the URL to browse it.
Note that on each version's page, there is a link at the top, e.g.
It is a link to the source for the commercial version of RStudio (RStudio Workbench), as indicated by the version number (ends in pro1). To get the source/commit hash you should usually start by opening the details for the binary you're trying to build from source. E.g. if you want to build Ghost Orchid (2021.09) for Windows, start here: