feat(frontend): aztec syntactic sugar (feature flagged)

[Maddiaa0]

Description

Linked work

• feat(attributes): enable custom attributes #2395
  • enabling custom attributes will allow the functions to be annotated accordingly
• feat(flags): add support for feature flags noirup#37
  • Adding the ability to use noirup to install from source with feature flags
• chore(ci): Allow releases to have additional feature flags #2405
  • Add the ability to publish releases with feature flags
• feat(noir): use #[aztec(private)] and #[aztec(public) attributes AztecProtocol/aztec-packages#1735
  • The pr in aztec-packages that makes use of this syntax upgrade

Performs some code generation on aztec annotated functions.
The goal of this PR is to abstract the app developer away from boilerplate code that is required to make noir compatible with the aztec execution environment.

For example what originally was:

    fn mint(
        inputs: PrivateContextInputs,
        amount: Field, 
        owner: Field
    ) -> distinct pub abi::PrivateCircuitPublicInputs {
        let storage = Storage::init();
        let mut context = PrivateContext::new(inputs, abi::hash_args([amount, owner]));

        // Insert new note to a set of user notes and emit the newly created encrypted note preimage via oracle call.
        let owner_balance = storage.balances.at(owner);
        send_note(&mut context, owner_balance, amount, owner);
        emit_unencrypted_log(&mut context, "Coins minted");

        // Return private circuit public inputs. All private functions need to return this as it is part of the input of the private kernel..
        context.finish()
    }

can instead be written as:

   #[aztec(private)]
    fn mint(
        amount: Field, 
        owner: Field
    )  {
        let storage = Storage::init();

        // Insert new note to a set of user notes and emit the newly created encrypted note preimage via oracle call.
        let owner_balance = storage.balances.at(owner);
        send_note(&mut context, owner_balance, amount, owner);
        emit_unencrypted_log(&mut context, "Coins minted");
    }

This will reduce the barrier for entry to new devs, making the syntax alot more approachable for them.

What does it abstract away
There is an execution context created in each function that allows the developer to:

• create commitments
• consume l1 messages
• interact with oracles required by the aztec-noir library
  among many other things.

This context is created by providing set inputs to each circuit (depending on the execution environment) and by hashing the other circuit inputs.

At the end of each call the inputs for the kernel iteration must be set as public inputs (returned). This is done with a call to context.finish().

Each macro:

• adds the input to the function
• hashes the args
• creates a context object
• inserts a context.finish() call

As the "macro" inserts the "context" into the ast, the context object is available to them as it it was something like solidity's block or msg structures.

subnote:
The storage pattern has not been added to this just yet as we have not concretely standardised this pattern. This shall be follow up work

Documentation

• This PR requires documentation updates when merged.

  • I will submit a noir-lang/docs PR.
  • I will request for and support Dev Rel's help in documenting this PR.

Additional Context

PR Checklist*

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt on default settings.

[jfecher]

can instead be written as:

   #[aztec(private)]
    fn mint(
        amount: Field, 
        owner: Field
    )  {
        let storage = Storage::init();

        // Insert new note to a set of user notes and emit the newly created encrypted note preimage via oracle call.
        let owner_balance = storage.balances.at(owner);
        send_note(&mut context, owner_balance, amount, owner);
        emit_unencrypted_log(&mut context, "Coins minted");
    }

Can you make it so the let storage = Storage::init(); line is inserted implicitly as well?

[Maddiaa0]

Can you make it so the let storage = Storage::init(); line is inserted implicitly as well?

We havent finalized this standard in the Aztec team. Once it is final i will make a followup pr

[jfecher]

I'm considering this temporary code so I only skimmed it. We can add to it/fix it later if needed

[ludamad]

based