Compare script language defaults

[vmcj]

If/When this is approved we need another PR to also use these values in the run/build scripts per language to fully implement the CLICS spec. Given that we don't implement the draft yet we have some time still.

One import thing is that I've changed the python to pypy3 to be consistent, this will require that this is installed in the host so I'm not sure if the consistency is wanted.

[meisterT]

I cannot really review this on my tiny phone screen, just wanted to leave two comments:

I started some work in this direction here #1241 - we probably want to use the same mechanism to pass in flags for both?

Historically speaking, we decided explicitly not to use the configured languages as you might have different options for submissions and validators. I think this is worth reconsidering; my current gut feeling is that we could do something like this:
Have per language an executable defined with which validators are compiled as well custom flags and a boolean, e.g. to disallow Python as submission language but allow it as validator language. If allowed as submission language but not separate executable / flags are set, we fall back to the configuration for submissions.

[vmcj]

I cannot really review this on my tiny phone screen, just wanted to leave two comments:

I'll wait for you to be on a larger screen,

I started some work in this direction here #1241 - we probably want to use the same mechanism to pass in flags for both?

That was the intent, I extended the language object with the CLICS flags {runner,compiler} where you had those specific for the _version. If that is not available we use the old defaults of the judgedaemon.

Historically speaking, we decided explicitly not to use the configured languages as you might have different options for submissions and validators. I think this is worth reconsidering; my current gut feeling is that we could do something like this: Have per language an executable defined with which validators are compiled as well custom flags and a boolean, e.g. to disallow Python as submission language but allow it as validator language. If allowed as submission language but not separate executable / flags are set, we fall back to the configuration for submissions.

This PR was to work towards #1238, where it was proposed (if I understand correctly) to explicit use the same options.

[meisterT]

If I understand things correctly, after this PR languages will have fields in the UI that ask for compiler/runner and their args. But these commands are not used for the submission language, and only for the validators which can be very confusing (while the code is clean).

My proposal is actually to not introduce the new fields in the UI as a first step, but move to using the same executables that we use for submission languages for validators.

This will allow us to:

• Eventually split them again, e.g. allow to define a "submission executable" and "validator executable" per language (where we fall back to the submission executable if no validator executable is defined). As well as having a "allow for validation" toggle, so you could allow say python validators but disallow python as submission language. This should help with addressing Compare scripts should be build using language defaults #1238.
• Add compiler/runner and their args in a separate step since this requires some thorough thinking of how this works with invalidating caching in the judging backend.

[vmcj]

If I understand things correctly, after this PR languages will have fields in the UI that ask for compiler/runner and their args. But these commands are not used for the submission language, and only for the validators which can be very confusing (while the code is clean).

My proposal is actually to not introduce the new fields in the UI as a first step, but move to using the same executables that we use for submission languages for validators.

This will allow us to:

* Eventually split them again, e.g. allow to define a "submission executable" and "validator executable" per language (where we fall back to the submission executable if no validator executable is defined). As well as having a "allow for validation" toggle, so you could allow say python validators but disallow python as submission language. This should help with addressing [Compare scripts should be build using language defaults #1238](https://github.com/DOMjudge/domjudge/issues/1238).

* Add compiler/runner and their args in a separate step since this requires some thorough thinking of how this works with invalidating caching in the judging backend.

Makes sense, so I'll close this for now.