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Rust codegen Phantom handling bug

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
35/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
haskell, rust
Domain
compilers

Research direction

Start at lambda-buffers-codegen/src/LambdaBuffers/Codegen/Rust/Print/TyDef.hs around line 177 and inspect how the shown LambdaBuffers definitions become Rust structs. Compare the generated CreateScriptsRequest and ScriptDatum output, checking both the unnecessary phantom_A field and visibility of phantom values. Done means the generated Rust representation matches the source type definitions and handles genuine phantom types correctly.

Written by the indexing model from the issue text.

Description

codegen

Phantom handling in Rust codegen is not correct I believe https://github.com/mlabs-haskell/lambda-buffers/blob/401f8a920a557c71440795174da199a1e128c4f9/lambda-buffers-codegen/src/LambdaBuffers/Codegen/Rust/Print/TyDef.hs#L177

record CreateScriptsRequest a = {
  scripts : Map ScriptHash (ScriptDatum a)
  }
derive Eq (CreateScriptsRequest a)
derive Json (CreateScriptsRequest a)

record ScriptDatum a = {
  scriptType : a,
  -- ^ Protocol specific script type stored in this UTxO
  redeemer : AssetClass
  -- ^ Wallet containing `$redeemer` must sign the 'delete-script' transaction as an authorization method
}
derive Eq (ScriptDatum a)
derive PlutusData (ScriptDatum a)
derive Json (ScriptDatum a)

creates a

#[derive(std::fmt::Debug, std::clone::Clone)]
pub struct CreateScriptsRequest<A>{pub scripts: lbf_prelude::prelude::Map<lbf_plutus::plutus::v1::ScriptHash
                                  ,crate::cardano::extra::scriptstorage::validation::ScriptDatum<A>>,
                                  phantom_A: std::marker::PhantomData<A>}

#[derive(std::fmt::Debug, std::clone::Clone)]
pub struct ScriptDatum<A>{pub script_type: A,
                         pub redeemer: lbf_plutus::plutus::v1::AssetClass}

There's 2 problems here.

  1. There's no actual phantom types in the original LB type def
  2. Even if there was, we have a problem when phantom values are not made pub in Rust
Dominant language
Haskell
Stars
32
Forks
1
PR merge metrics
No merged PRs in 30d

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