Improve guide for development with CLion

[badlogic]

This improved guide describes how to use the compilation database generated by SCons to work on Godot with CLion. It also describes a setup that allows single click cleaning/building/debugging/profiling of the Godot editor directly from within CLion. As a heavy CLion user, I can confirm that this should be the preferred workflow when using CLion for Godot development.

[Calinou]

One issue that was raised on the Godot contributors chat is that CLion doesn't seem to expand shell command usage such as scons -j$(nproc). This causes an error as $(nproc) will be passed as-is to the SCons command, while it should be converted to a numeric value by the shell.

The documentation should probably have a warning about this, telling the user to replace -j$(nproc), -j%NUMBER_OF_PROCESSORS or -j$(sysctl -n hw.logicalcpu) with a fixed amount of CPU cores like -j8.

To resolve this in the future, I requested the addition of an universal --parallel command line option on the SCons mailing list: https://pairlist4.pair.net/pipermail/scons-users/2022-April/008840.html

[badlogic]

Thank you for the swift review and sorry for the many edits you had to make.

Bill had a very good suggestion over on the SCons mailing list regarding the -j issue: https://pairlist4.pair.net/pipermail/scons-users/2022-April/008841.html

I suppose this could make it into Godot's SConstruct file as a default? I'll add a callout regarding -j to this PR for the current setup.

[mhilbrunner]

Nice to see you around these parts :) Looks good to me.

I'll wait for your amendment before merging. A squash would be appreciated!
Some of the screenshots seem on the larger side, but if you're busy I can run a compressor on them.

Edit:

Bill had a very good suggestion over on the SCons mailing list regarding the -j issue: https://pairlist4.pair.net/pipermail/scons-users/2022-April/008841.html

I suppose this could make it into Godot's SConstruct file as a default? I'll add a callout regarding -j to this PR for the current setup.

I'll see about this. There may be reasons we don't currently do this, but I'm not aware.

[Calinou]

I'll see about this. There may be reasons we don't currently do this, but I'm not aware.

Relevant conversation on the Godot contributors chat in #buildsystem:

<Calinou> it looks like we can add a custom parallel=yes option to SCons to automatically use the number of CPU threads on the system: https://pairlist4.pair.net/pipermail/scons-users/2022-April/008841.html
pairlist4.pair.net
<Calinou> the reason for doing this is that it will work well in IDEs that don't expand shell commands or variables, and it avoids having to remember one-liners for each platform 🙂
<Calinou> it needs to be optional though, as you can't override the number of threads with -j if you override it in your SCons setup. It could be enabled by default, but this would require users to use parallel=no -j1 to override it

<Akien> It could likely still be overridden, you can check in the code block for if env["parallel"] whether there's a -j X in the args list.
<Akien> Ah no, -j doesn't register in the ARGUMENTS dict.

[badlogic]

@mhilbrunner @Calinou Sorry for this taking so long. I've now amended the PR as discussed and squashed the commits. Thank you for your review.

[Calinou]

Thanks! Congratulations for your first merged pull request 🎉