Optional fvm for curio

[snadrus]

This simple change reduces Curio build time & saves 24mb off Curio's final filesize.
fvm becomes optional=true instead of required.

[Copilot]

Pull Request Overview

This PR makes FVM (Filecoin Virtual Machine) dependencies optional by introducing a feature flag system. The changes allow building the project without FVM support, reducing dependencies for users who don't require FVM functionality.

• Moved FVM module in Rust behind a fvm feature flag
• Made all FVM-related Rust dependencies optional
• Added fvm build tag to Go files to conditionally compile FVM code
• Provided C header fallback definitions for FVM error constants when FVM is disabled

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
rust/src/lib.rs	Wrapped FVM module declaration with cfg(feature = "fvm") conditional compilation
rust/Cargo.toml	Made FVM dependencies optional and created an fvm feature that includes them; added fvm to default features
fvm.go	Added fvm build tag to conditionally compile FVM functionality
cgo/types.go	Removed FVM type definitions and helpers, replaced with comments referencing types_fvm.go
cgo/fvm.go	Added fvm build tag to conditionally compile FVM CGO bindings
cgo/errors.go	Added fallback C macro definitions for FVM error constants when FVM is not compiled

Comments suppressed due to low confidence (3)

rust/Cargo.toml:76

• The cuda feature unconditionally references fvm2/cuda, fvm3/cuda, and fvm4/cuda, but these dependencies are now optional (only available when the fvm feature is enabled). This will cause build failures when using --no-default-features --features cuda. The FVM sub-features should be made conditional on the fvm feature, for example: dep:fvm2?/cuda or the feature should depend on fvm.

cuda = [
  "filecoin-proofs-api/cuda",
  "rust-gpu-tools/cuda",
  "fvm2/cuda",
  "fvm3/cuda",
  "fvm4/cuda",
]

rust/Cargo.toml:82

• The cuda-supraseal feature unconditionally references fvm3/cuda-supraseal and fvm4/cuda-supraseal, but these dependencies are now optional. This will cause build failures when using --no-default-features --features cuda-supraseal. The FVM sub-features should be made conditional on the fvm feature.

cuda-supraseal = [
  "filecoin-proofs-api/cuda-supraseal",
  "rust-gpu-tools/cuda",
  "fvm3/cuda-supraseal",
  "fvm4/cuda-supraseal",
]

rust/Cargo.toml:89

• The opencl feature unconditionally references fvm2/opencl, fvm3/opencl, and fvm4/opencl, but these dependencies are now optional. This will cause build failures when using --no-default-features --features opencl. The FVM sub-features should be made conditional on the fvm feature.

opencl = [
  "filecoin-proofs-api/opencl",
  "rust-gpu-tools/opencl",
  "fvm2/opencl",
  "fvm3/opencl",
  "fvm4/opencl",
]

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[rvagg]

Aside from the disable logic flip this lgtm, 🤞 and we'll find out pretty quick when we try to use it!

[snadrus]

Please merge @rvagg as I don't have permission