Use Windows registry to find R path

[renkun-ken]

What problem did you solve?

Closes #244

(If you do not have screenshot) How can I check this pull request?

If a Windows user installs R with default installation settings, the R path will be added to registry. So that user does not have to specify R executable in this case.

To test it, set rterm.windows to empty (now it's empty by default), run Create R Terminal and see if it could properly find R path and create a terminal with it.

Another thing to test is that if multiple versions are installed, the registry will contain multiple entries of R paths. Although the registry entry will have multiple subentries in this case, the value of the key should be the last installed version.

[renkun-ken]

I tested this on my Windows 10 VM and it works as expected.

To test, please download the build at https://github.com/Ikuyadeu/vscode-R/actions/runs/49221093 or see the artifacts in the details of main / build (pull_request).

[andycraig]

@renkun-ken I tried testing this just now on Windows 10, but no success I'm afraid.

Testing using VSIX file:

Cannot find R client.  Please check R path in preferences and reload.

Just to check, I also tested by running your win-find-rpath branch in debug mode:

Activating extension 'Ikuyadeu.r' failed: Cannot find module 'winreg'.
command 'r.createRTerm' not found

Not sure if it helps, but this is what my registry looks like:

Full key is like Computer\HKEY_LOCAL_MACHINE\SOFTWARE\R-core\R\3.4.1

[ksq]

I test with the VSIX at https://github.com/Ikuyadeu/vscode-R/actions/runs/49233584 and it works perfectly on my Windows 10.

My registry looks like

[renkun-ken]

@andycraig We use R's InstallPath key rather than any sub-entries such as 3.4.4 or 3.6.3.
Would you like to take a look at the keys R has?

[andycraig]

@renkun-ken Looks like that's the issue in my case. InstallPath seems to be under 3.4.1 rather than R:

[renkun-ken]

@andycraig I see. I'm not sure if newer versions of R will write to both R and R/3.x.y, or maybe it could also be caused by uninstalling the last installed version.

We are using almost the same code as in vscode-r-lsp and its default value. Therefore we are consistent with it too. If user does not have the R executable path correctly written in R/InstallPath, then user should specify path in VSCode settings for both vscode-R and vscode-r-lsp. Maybe we should make it more clear in the documentation or error message?

[andycraig]

@ksq Thank you for testing!

@renkun-ken Yeah, the version of R I have installed on Windows is old so that could well be it.

It worked for @ksq, and for me it displayed the appropriate error message. The README is very clear as well. I am happy with it as-is. Please merge it if you have no additional changes.

Thank you for this PR! It will make it simpler for new users.