serde should not be optional

[schoen]

Project

compiler

Describe the feature

There's a weird thing that I remember from the bootcamps back in October/November 2025 where simc can only serialize witnesses if it's compiled with serde. The simc --help output even mentions this issue.

I don't think there's ever any reason to make a version of simc that can't serialize witnesses, so I think serde (or something else that provides equivalent functionality) should be a mandatory dependency, and no help or documentation should mention the possibility of having a non-serde version of simc.

[apoelstra]

Yeah, agreed. We are using serde for pretty essential functionality. We should just make it a required dep.

[stringhandler]

It is actually compiled in by default, because the default features include it.

[features]
default = [ "serde" ]
serde = ["dep:serde", "dep:serde_json"]

You can exclude it by specifying --default-features=false. I think this is good practice to keep it, but might be unnecessary.

[apoelstra]

Welcome @stringhandler!

True -- now that it's a default feature, at least cargo run isn't broken. But I still feel you shouldn't be able to disable it at all.

It's extra code maintenance for us to feature-gate large chunks of CLI logic (and I'm not totally convinced the feature is additive, given that we're using it to gate logic in main() rather than the more normal thing of gating modules/functions/types) and I think the user experience without the feature is simply "this is broken and doesn't match the docs".