feat!: introduce UnconstrainedContext

docs/docs/migration_notes.md

@@ -8,6 +8,17 @@ Aztec is in full-speed development. Literally every version breaks compatibility
 
 ## 0.42.0
 
+### [Aztec.nr] Unconstrained Context
+
+Top-level unconstrained execution is now marked by the new `UnconstrainedContext`, which provides access to the block number and contract address being used in the simulation. Any custom state variables that provided unconstrained functions should update their specialization parameter:
+
+```diff
++ use dep::aztec::context::UnconstrainedContext;
+
+- impl MyStateVariable<()> {
++ impl MyStateVariable<UnconstrainedContext> {
+```
+
 ### [Aztec.nr] Filtering is now constrained
 
 The `filter` argument of `NoteGetterOptions` (typically passed via the `with_filter()` function) is now applied in a constraining environment, meaning any assertions made during the filtering are guaranteed to hold. This mirrors the behavior of the `select()` function.

docs/docs/reference/smart_contract_reference/storage/index.md

@@ -27,9 +27,10 @@ On this and the following pages in this section, you’ll learn:
 Aztec contracts have three different modes of execution: [private](../../../aztec/glossary/call_types.md#private-execution), [public](../../../aztec/glossary/call_types.md#public-execution) and [top-level unconstrained](../../../aztec/glossary/call_types.md#top-level-unconstrained). How storage is accessed depends on the execution mode: for example, `PublicImmutable` can be read in all execution modes but only initialized in public, while `PrivateMutable` is entirely unavailable in public.
 
 Aztec.nr prevents developers from calling functions unavailable in the current execution mode via the `context` variable that is injected into all contract functions. Its type indicates the current execution mode:
- - `&mut PrivateContext` for private execution
- - `&mut PublicContext` for public execution
- - `()` for unconstrained
+
+- `&mut PrivateContext` for private execution
+- `&mut PublicContext` for public execution
+- `UncontrainedContext` for top-level unconstrained execution
 
 All state variables are generic over this `Context` type, and expose different methods in each execution mode. In the example above, `PublicImmutable`'s `initialize` function is only available with a public execution context, and so the following code results in a compilation error:
 

noir-projects/aztec-nr/aztec/src/context.nr

@@ -4,6 +4,8 @@ mod inputs;
 mod packed_returns;
 mod private_context;
 mod public_context;
+mod unconstrained_context;
+
 mod call_interfaces;
 mod gas;
 
@@ -16,3 +18,4 @@ use private_context::PrivateContext;
 use packed_returns::PackedReturns;
 use public_context::PublicContext;
 use public_context::FunctionReturns;
+use unconstrained_context::UnconstrainedContext;

noir-projects/aztec-nr/aztec/src/context/unconstrained_context.nr

@@ -0,0 +1,32 @@
+use dep::protocol_types::address::AztecAddress;
+
+struct UnconstrainedContext {
+    block_number: u32,
+    contract_address: AztecAddress,    
+}
+
+impl UnconstrainedContext {
+    fn new() -> Self {
+        // We could call these oracles on the getters instead of at creation, which makes sense given that they might
+        // not even be accessed. However any performance gains are minimal, and we'd rather fail early if a user
+        // incorrectly attempts to create an UnconstrainedContext in an environment in which these oracles are not
+        // available.
+        let block_number = block_number_oracle();
+        let contract_address = contract_address_oracle();
+        Self { block_number, contract_address }
+    }
+
+    fn block_number(self) -> u32 {
+        self.block_number
+    }
+
+    fn contract_address(self) -> AztecAddress {
+        self.contract_address
+    }
+}
+
+#[oracle(getContractAddress)]
+fn contract_address_oracle() -> AztecAddress {}
+
+#[oracle(getBlockNumber)]
+fn block_number_oracle() -> u32 {}

noir-projects/aztec-nr/aztec/src/state_vars/private_immutable.nr

@@ -3,7 +3,7 @@ use dep::protocol_types::{
     constants::GENERATOR_INDEX__INITIALIZATION_NULLIFIER, hash::pedersen_hash
 };
 
-use crate::context::PrivateContext;
+use crate::context::{PrivateContext, UnconstrainedContext};
 use crate::note::{
     lifecycle::create_note, note_getter::{get_note, view_notes}, note_interface::NoteInterface,
     note_viewer_options::NoteViewerOptions
@@ -66,7 +66,7 @@ impl<Note> PrivateImmutable<Note, &mut PrivateContext> {
     // docs:end:get_note
 }
 
-impl<Note> PrivateImmutable<Note, ()> {
+impl<Note> PrivateImmutable<Note, UnconstrainedContext> {
     // docs:start:is_initialized
     unconstrained pub fn is_initialized(self) -> bool {
         let nullifier = self.compute_initialization_nullifier();

noir-projects/aztec-nr/aztec/src/state_vars/private_mutable.nr

@@ -3,7 +3,7 @@ use dep::protocol_types::{
     grumpkin_point::GrumpkinPoint, hash::pedersen_hash
 };
 
-use crate::context::PrivateContext;
+use crate::context::{PrivateContext, UnconstrainedContext};
 use crate::note::{
     lifecycle::{create_note, destroy_note}, note_getter::{get_note, view_notes},
     note_interface::NoteInterface, note_viewer_options::NoteViewerOptions
@@ -124,7 +124,7 @@ impl<Note> PrivateMutable<Note, &mut PrivateContext> {
     // docs:end:get_note
 }
 
-impl<Note> PrivateMutable<Note, ()> {
+impl<Note> PrivateMutable<Note, UnconstrainedContext> {
     unconstrained pub fn is_initialized(self) -> bool {
         let nullifier = self.compute_initialization_nullifier();
         check_nullifier_exists(nullifier)

noir-projects/aztec-nr/aztec/src/state_vars/private_set.nr

@@ -2,7 +2,7 @@ use dep::protocol_types::{
     constants::MAX_NOTE_HASH_READ_REQUESTS_PER_CALL, abis::read_request::ReadRequest,
     grumpkin_point::GrumpkinPoint
 };
-use crate::context::{PrivateContext, PublicContext};
+use crate::context::{PrivateContext, PublicContext, UnconstrainedContext};
 use crate::note::{
     constants::MAX_NOTES_PER_PAGE, lifecycle::{create_note, create_note_hash_from_public, destroy_note},
     note_getter::{get_notes, view_notes}, note_getter_options::NoteGetterOptions,
@@ -85,7 +85,7 @@ impl<Note> PrivateSet<Note, &mut PrivateContext> {
     // docs:end:get_notes
 }
 
-impl<Note> PrivateSet<Note, ()> {
+impl<Note> PrivateSet<Note, UnconstrainedContext> {
     // docs:start:view_notes
     unconstrained pub fn view_notes<N, M>(
         self,

noir-projects/aztec-nr/aztec/src/state_vars/public_immutable.nr

@@ -1,4 +1,7 @@
-use crate::{context::PublicContext, oracle::{storage::{storage_read, storage_write}}, state_vars::storage::Storage};
+use crate::{
+    context::{PublicContext, UnconstrainedContext}, oracle::{storage::{storage_read, storage_write}},
+    state_vars::storage::Storage
+};
 use dep::protocol_types::{constants::INITIALIZATION_SLOT_SEPARATOR, traits::{Deserialize, Serialize}};
 
 // Just like SharedImmutable but without the ability to read from private functions.
@@ -54,11 +57,11 @@ impl <T> PublicImmutable<T, &mut PublicContext> {
     // docs:end:public_immutable_struct_read
 }
 
-impl<T> PublicImmutable<T, ()> {
+impl<T> PublicImmutable<T, UnconstrainedContext> {
     pub fn read<T_SERIALIZED_LEN>(self) -> T where T: Deserialize<T_SERIALIZED_LEN> {
-        // Note that this is the exact same implementation as for public execution, though it might change in the future
-        // since unconstrained execution might not rely on the same oracles as used for public execution (which 
-        // transpile to AVM opcodes).
+        // This looks the same as the &mut PublicContext impl, but is actually very different. In public execution the
+        // storage read oracle gets transpiled to SLOAD opcodes, whereas in unconstrained execution the PXE returns
+        // historical data.
         let fields = storage_read(self.storage_slot);
         T::deserialize(fields)
     }

noir-projects/aztec-nr/aztec/src/state_vars/public_mutable.nr

@@ -1,4 +1,4 @@
-use crate::context::PublicContext;
+use crate::context::{PublicContext, UnconstrainedContext};
 use crate::oracle::storage::storage_read;
 use crate::oracle::storage::storage_write;
 use dep::protocol_types::traits::{Deserialize, Serialize};
@@ -42,11 +42,11 @@ impl<T> PublicMutable<T, &mut PublicContext> {
     // docs:end:public_mutable_struct_write
 }
 
-impl<T> PublicMutable<T, ()> {
+impl<T> PublicMutable<T, UnconstrainedContext> {
     pub fn read<T_SERIALIZED_LEN>(self) -> T where T: Deserialize<T_SERIALIZED_LEN> {
-        // Note that this is the exact same implementation as for public execution, though it might change in the future
-        // since unconstrained execution might not rely on the same oracles as used for public execution (which 
-        // transpile to AVM opcodes).
+        // This looks the same as the &mut PublicContext impl, but is actually very different. In public execution the
+        // storage read oracle gets transpiled to SLOAD opcodes, whereas in unconstrained execution the PXE returns
+        // historical data.
         let fields = storage_read(self.storage_slot);
         T::deserialize(fields)
     }

noir-projects/aztec-nr/aztec/src/state_vars/shared_immutable.nr

@@ -1,6 +1,6 @@
 use crate::{
-    context::{PrivateContext, PublicContext}, oracle::{storage::{storage_read, storage_write}},
-    state_vars::storage::Storage
+    context::{PrivateContext, PublicContext, UnconstrainedContext},
+    oracle::{storage::{storage_read, storage_write}}, state_vars::storage::Storage
 };
 use dep::protocol_types::{constants::INITIALIZATION_SLOT_SEPARATOR, traits::{Deserialize, Serialize}};
 
@@ -49,7 +49,7 @@ impl<T> SharedImmutable<T, &mut PublicContext> {
     }
 }
 
-impl<T> SharedImmutable<T, ()> {
+impl<T> SharedImmutable<T, UnconstrainedContext> {
     pub fn read_public<T_SERIALIZED_LEN>(self) -> T where T: Deserialize<T_SERIALIZED_LEN> {
         let fields = storage_read(self.storage_slot);
         T::deserialize(fields)

noir-projects/aztec-nr/value-note/src/balance_utils.nr

@@ -1,12 +1,14 @@
-use dep::aztec::note::{note_getter::view_notes, note_viewer_options::NoteViewerOptions};
-use dep::aztec::state_vars::PrivateSet;
+use dep::aztec::{
+    context::UnconstrainedContext, state_vars::PrivateSet,
+    note::{note_getter::view_notes, note_viewer_options::NoteViewerOptions}
+};
 use crate::value_note::ValueNote;
 
-unconstrained pub fn get_balance(set: PrivateSet<ValueNote, ()>) -> Field {
+unconstrained pub fn get_balance(set: PrivateSet<ValueNote, UnconstrainedContext>) -> Field {
     get_balance_with_offset(set, 0)
 }
 
-unconstrained pub fn get_balance_with_offset(set: PrivateSet<ValueNote, ()>, offset: u32) -> Field {
+unconstrained pub fn get_balance_with_offset(set: PrivateSet<ValueNote, UnconstrainedContext>, offset: u32) -> Field {
     let mut balance = 0;
     // docs:start:view_notes
     let mut options = NoteViewerOptions::new();

noir-projects/noir-contracts/contracts/card_game_contract/src/cards.nr

@@ -1,6 +1,7 @@
 use dep::aztec::prelude::{AztecAddress, FunctionSelector, PrivateContext, NoteHeader, NoteGetterOptions, NoteViewerOptions};
 
 use dep::aztec::{
+    context::UnconstrainedContext,
     protocol_types::{
     traits::{ToField, Serialize, FromField}, grumpkin_point::GrumpkinPoint,
     constants::MAX_NOTE_HASH_READ_REQUESTS_PER_CALL
@@ -153,7 +154,7 @@ impl Deck<&mut PrivateContext> {
     }
 }
 
-impl Deck<()> {
+impl Deck<UnconstrainedContext> {
     unconstrained pub fn view_cards(self, offset: u32) -> [Option<Card>; MAX_NOTES_PER_PAGE] {
         let mut options = NoteViewerOptions::new();
         let opt_notes = self.set.view_notes(options.set_offset(offset));

noir-projects/noir-contracts/contracts/token_blacklist_contract/src/types/balances_map.nr

@@ -1,9 +1,7 @@
-use dep::aztec::prelude::{
-    AztecAddress, NoteGetterOptions, NoteViewerOptions, NoteHeader, NoteInterface, PrivateContext,
-    PrivateSet, Map
-};
+use dep::aztec::prelude::{AztecAddress, NoteGetterOptions, NoteViewerOptions, NoteHeader, NoteInterface, PrivateSet, Map};
 use dep::aztec::{
-    hash::pedersen_hash, protocol_types::constants::MAX_NOTE_HASH_READ_REQUESTS_PER_CALL,
+    context::{PrivateContext, UnconstrainedContext}, hash::pedersen_hash,
+    protocol_types::constants::MAX_NOTE_HASH_READ_REQUESTS_PER_CALL,
     note::{note_getter::view_notes, note_getter_options::SortOrder}
 };
 use crate::types::token_note::{TokenNote, OwnedNote};
@@ -25,7 +23,7 @@ impl<T, Context> BalancesMap<T, Context> {
     }
 }
 
-impl<T> BalancesMap<T, ()> {
+impl<T> BalancesMap<T, UnconstrainedContext> {
     unconstrained pub fn balance_of<T_SERIALIZED_LEN, T_SERIALIZED_BYTES_LEN>(
         self: Self,
         owner: AztecAddress

noir-projects/noir-contracts/contracts/token_contract/src/types/balances_map.nr

@@ -1,9 +1,7 @@
-use dep::aztec::prelude::{
-    AztecAddress, NoteGetterOptions, NoteViewerOptions, NoteHeader, NoteInterface, PrivateContext,
-    PrivateSet, Map
-};
+use dep::aztec::prelude::{AztecAddress, NoteGetterOptions, NoteViewerOptions, NoteHeader, NoteInterface, PrivateSet, Map};
 use dep::aztec::{
-    hash::pedersen_hash, protocol_types::constants::MAX_NOTE_HASH_READ_REQUESTS_PER_CALL,
+    context::{PrivateContext, UnconstrainedContext}, hash::pedersen_hash,
+    protocol_types::constants::MAX_NOTE_HASH_READ_REQUESTS_PER_CALL,
     note::{note_getter::view_notes, note_getter_options::SortOrder}
 };
 use crate::types::token_note::{TokenNote, OwnedNote};
@@ -25,7 +23,7 @@ impl<T, Context> BalancesMap<T, Context> {
     }
 }
 
-impl<T> BalancesMap<T, ()> {
+impl<T> BalancesMap<T, UnconstrainedContext> {
     unconstrained pub fn balance_of<T_SERIALIZED_LEN, T_SERIALIZED_BYTES_LEN>(
         self: Self,
         owner: AztecAddress

noir/noir-repo/aztec_macros/src/transforms/functions.rs

@@ -216,12 +216,30 @@ pub fn export_fn_abi(
 ///
 /// Inserts the following code at the beginning of an unconstrained function
 /// ```noir
-/// let storage = Storage::init(Context::none());
+/// let context = UnconstrainedContext::new();
+/// let storage = Storage::init(context);
 /// ```
 ///
 /// This will allow developers to access their contract' storage struct in unconstrained functions
 pub fn transform_unconstrained(func: &mut NoirFunction, storage_struct_name: String) {
+    // let context = UnconstrainedContext::new();
+    let let_context = assignment(
+        "context", // Assigned to
+        call(
+            variable_path(chained_dep!(
+                "aztec",
+                "context",
+                "unconstrained_context",
+                "UnconstrainedContext",
+                "new"
+            )),
+            vec![],
+        ),
+    );
+
+    // We inject the statements at the beginning, in reverse order.
     func.def.body.statements.insert(0, abstract_storage(storage_struct_name, true));
+    func.def.body.statements.insert(0, let_context);
 }
 
 /// Helper function that returns what the private context would look like in the ast
@@ -597,30 +615,26 @@ fn abstract_return_values(func: &NoirFunction) -> Result<Option<Vec<Statement>>,
 /// ```noir
 /// #[aztec(private)]
 /// fn lol() {
-///     let storage = Storage::init(context);
+///     let storage = Storage::init(&mut context);
 /// }
 /// ```
 ///
 /// For public functions:
 /// ```noir
 /// #[aztec(public)]
 /// fn lol() {
-///    let storage = Storage::init(context);
+///    let storage = Storage::init(&mut context);
 /// }
 /// ```
 ///
 /// For unconstrained functions:
 /// ```noir
 /// unconstrained fn lol() {
-///   let storage = Storage::init(());
+///   let storage = Storage::init(context);
 /// }
 fn abstract_storage(storage_struct_name: String, unconstrained: bool) -> Statement {
-    let context_expr = if unconstrained {
-        // Note that the literal unit type (i.e. '()') is not the same as a tuple with zero elements
-        expression(ExpressionKind::Literal(Literal::Unit))
-    } else {
-        mutable_reference("context")
-    };
+    let context_expr =
+        if unconstrained { variable("context") } else { mutable_reference("context") };
 
     assignment(
         "storage", // Assigned to

yarn-project/simulator/src/acvm/oracle/oracle.ts

@@ -41,6 +41,14 @@ export class Oracle {
     return unpacked.map(toACVMField);
   }
 
+  async getBlockNumber(): Promise<ACVMField> {
+    return toACVMField(await this.typedOracle.getBlockNumber());
+  }
+
+  async getContractAddress(): Promise<ACVMField> {
+    return toACVMField(await this.typedOracle.getContractAddress());
+  }
+
   async getKeyValidationRequest([pkMHash]: ACVMField[]): Promise<ACVMField[]> {
     const { pkM, skApp } = await this.typedOracle.getKeyValidationRequest(fromACVMField(pkMHash));
 

yarn-project/simulator/src/acvm/oracle/typed_oracle.ts

@@ -82,6 +82,14 @@ export abstract class TypedOracle {
     throw new OracleMethodNotAvailableError('unpackReturns');
   }
 
+  getBlockNumber(): Promise<number> {
+    throw new OracleMethodNotAvailableError('getBlockNumber');
+  }
+
+  getContractAddress(): Promise<AztecAddress> {
+    throw new OracleMethodNotAvailableError('getContractAddress');
+  }
+
   getKeyValidationRequest(_pkMHash: Fr): Promise<KeyValidationRequest> {
     throw new OracleMethodNotAvailableError('getKeyValidationRequest');
   }

yarn-project/simulator/src/client/unconstrained_execution.test.ts

@@ -17,6 +17,10 @@ describe('Unconstrained Execution test suite', () => {
 
   beforeEach(() => {
     oracle = mock<DBOracle>();
+
+    node = mock<AztecNode>();
+    node.getBlockNumber.mockResolvedValue(42);
+
     acirSimulator = new AcirSimulator(oracle, node);
   });