feat: replace eval_global_as_array_length with type/interpreter eva…

…luation (#6469)

Co-authored-by: Tom French <15848336+TomAFrench@users.noreply.github.com>
Co-authored-by: jfecher <jake@aztecprotocol.com>
Co-authored-by: Ary Borenszweig <asterite@gmail.com>

compiler/noirc_frontend/src/ast/statement.rs

@@ -154,6 +154,7 @@ impl StatementKind {
             r#type,
             expression,
             comptime: false,
+            is_global_let: false,
             attributes,
         })
     }
@@ -562,6 +563,7 @@ pub struct LetStatement {
 
     // True if this should only be run during compile-time
     pub comptime: bool,
+    pub is_global_let: bool,
 }
 
 #[derive(Debug, PartialEq, Eq, Clone)]

compiler/noirc_frontend/src/elaborator/mod.rs

@@ -1652,20 +1652,13 @@ impl<'context> Elaborator<'context> {
             self.push_err(ResolverError::MutableGlobal { span });
         }
 
-        let comptime = let_stmt.comptime;
-
-        let (let_statement, _typ) = if comptime {
-            self.elaborate_in_comptime_context(|this| this.elaborate_let(let_stmt, Some(global_id)))
-        } else {
-            self.elaborate_let(let_stmt, Some(global_id))
-        };
+        let (let_statement, _typ) = self
+            .elaborate_in_comptime_context(|this| this.elaborate_let(let_stmt, Some(global_id)));
 
         let statement_id = self.interner.get_global(global_id).let_statement;
         self.interner.replace_statement(statement_id, let_statement);
 
-        if comptime {
-            self.elaborate_comptime_global(global_id);
-        }
+        self.elaborate_comptime_global(global_id);
 
         if let Some(name) = name {
             self.interner.register_global(global_id, name, global.visibility, self.module_id());
@@ -1700,6 +1693,16 @@ impl<'context> Elaborator<'context> {
         }
     }
 
+    /// If the given global is unresolved, elaborate it and return true
+    fn elaborate_global_if_unresolved(&mut self, global_id: &GlobalId) -> bool {
+        if let Some(global) = self.unresolved_globals.remove(global_id) {
+            self.elaborate_global(global);
+            true
+        } else {
+            false
+        }
+    }
+
     fn define_function_metas(
         &mut self,
         functions: &mut [UnresolvedFunctions],

compiler/noirc_frontend/src/elaborator/patterns.rs

@@ -666,9 +666,7 @@ impl<'context> Elaborator<'context> {
                         self.interner.add_function_reference(func_id, hir_ident.location);
                     }
                     DefinitionKind::Global(global_id) => {
-                        if let Some(global) = self.unresolved_globals.remove(&global_id) {
-                            self.elaborate_global(global);
-                        }
+                        self.elaborate_global_if_unresolved(&global_id);
                         if let Some(current_item) = self.current_item {
                             self.interner.add_global_dependency(current_item, global_id);
                         }

compiler/noirc_frontend/src/elaborator/statements.rs

@@ -76,6 +76,7 @@ impl<'context> Elaborator<'context> {
     ) -> (HirStatement, Type) {
         let expr_span = let_stmt.expression.span;
         let (expression, expr_type) = self.elaborate_expression(let_stmt.expression);
+
         let type_contains_unspecified = let_stmt.r#type.contains_unspecified();
         let annotated_type = self.resolve_inferred_type(let_stmt.r#type);
 
@@ -123,7 +124,9 @@ impl<'context> Elaborator<'context> {
 
         let attributes = let_stmt.attributes;
         let comptime = let_stmt.comptime;
-        let let_ = HirLetStatement { pattern, r#type, expression, attributes, comptime };
+        let is_global_let = let_stmt.is_global_let;
+        let let_ =
+            HirLetStatement::new(pattern, r#type, expression, attributes, comptime, is_global_let);
         (HirStatement::Let(let_), Type::Unit)
     }
 

compiler/noirc_frontend/src/elaborator/types.rs

@@ -1,6 +1,5 @@
 use std::{borrow::Cow, rc::Rc};
 
-use acvm::acir::AcirField;
 use iter_extended::vecmap;
 use noirc_errors::{Location, Span};
 use rustc_hash::FxHashMap as HashMap;
@@ -12,7 +11,6 @@ use crate::{
         UnresolvedTypeData, UnresolvedTypeExpression, WILDCARD_TYPE,
     },
     hir::{
-        comptime::{Interpreter, Value},
         def_collector::dc_crate::CompilationError,
         resolution::{errors::ResolverError, import::PathResolutionError},
         type_check::{
@@ -30,8 +28,8 @@ use crate::{
         traits::{NamedType, ResolvedTraitBound, Trait, TraitConstraint},
     },
     node_interner::{
-        DefinitionKind, DependencyId, ExprId, GlobalId, ImplSearchErrorKind, NodeInterner, TraitId,
-        TraitImplKind, TraitMethodId,
+        DependencyId, ExprId, ImplSearchErrorKind, NodeInterner, TraitId, TraitImplKind,
+        TraitMethodId,
     },
     token::SecondaryAttribute,
     Generics, Kind, ResolvedGeneric, Type, TypeBinding, TypeBindings, UnificationError,
@@ -415,17 +413,40 @@ impl<'context> Elaborator<'context> {
                     .map(|let_statement| Kind::numeric(let_statement.r#type))
                     .unwrap_or(Kind::u32());
 
-                // TODO(https://github.com/noir-lang/noir/issues/6238):
-                // support non-u32 generics here
-                if !kind.unifies(&Kind::u32()) {
-                    let error = TypeCheckError::EvaluatedGlobalIsntU32 {
-                        expected_kind: Kind::u32().to_string(),
-                        expr_kind: kind.to_string(),
-                        expr_span: path.span(),
-                    };
-                    self.push_err(error);
-                }
-                Some(Type::Constant(self.eval_global_as_array_length(id, path).into(), kind))
+                let Some(stmt) = self.interner.get_global_let_statement(id) else {
+                    if self.elaborate_global_if_unresolved(&id) {
+                        return self.lookup_generic_or_global_type(path);
+                    } else {
+                        let path = path.clone();
+                        self.push_err(ResolverError::NoSuchNumericTypeVariable { path });
+                        return None;
+                    }
+                };
+
+                let rhs = stmt.expression;
+                let span = self.interner.expr_span(&rhs);
+
+                let Some(global_value) = &self.interner.get_global(id).value else {
+                    self.push_err(ResolverError::UnevaluatedGlobalType { span });
+                    return None;
+                };
+
+                let Some(global_value) = global_value.to_field_element() else {
+                    let global_value = global_value.clone();
+                    if global_value.is_integral() {
+                        self.push_err(ResolverError::NegativeGlobalType { span, global_value });
+                    } else {
+                        self.push_err(ResolverError::NonIntegralGlobalType { span, global_value });
+                    }
+                    return None;
+                };
+
+                let Ok(global_value) = kind.ensure_value_fits(global_value, span) else {
+                    self.push_err(ResolverError::GlobalLargerThanKind { span, global_value, kind });
+                    return None;
+                };
+
+                Some(Type::Constant(global_value, kind))
             }
             _ => None,
         }
@@ -633,31 +654,6 @@ impl<'context> Elaborator<'context> {
             .or_else(|| self.resolve_trait_method_by_named_generic(path))
     }
 
-    fn eval_global_as_array_length(&mut self, global_id: GlobalId, path: &Path) -> u32 {
-        let Some(stmt) = self.interner.get_global_let_statement(global_id) else {
-            if let Some(global) = self.unresolved_globals.remove(&global_id) {
-                self.elaborate_global(global);
-                return self.eval_global_as_array_length(global_id, path);
-            } else {
-                let path = path.clone();
-                self.push_err(ResolverError::NoSuchNumericTypeVariable { path });
-                return 0;
-            }
-        };
-
-        let length = stmt.expression;
-        let span = self.interner.expr_span(&length);
-        let result = try_eval_array_length_id(self.interner, length, span);
-
-        match result.map(|length| length.try_into()) {
-            Ok(Ok(length_value)) => return length_value,
-            Ok(Err(_cast_err)) => self.push_err(ResolverError::IntegerTooLarge { span }),
-            Err(Some(error)) => self.push_err(error),
-            Err(None) => (),
-        }
-        0
-    }
-
     pub(super) fn unify(
         &mut self,
         actual: &Type,
@@ -1834,88 +1830,6 @@ fn bind_generic(param: &ResolvedGeneric, arg: &Type, bindings: &mut TypeBindings
     }
 }
 
-pub fn try_eval_array_length_id(
-    interner: &NodeInterner,
-    rhs: ExprId,
-    span: Span,
-) -> Result<u128, Option<ResolverError>> {
-    // Arbitrary amount of recursive calls to try before giving up
-    let fuel = 100;
-    try_eval_array_length_id_with_fuel(interner, rhs, span, fuel)
-}
-
-fn try_eval_array_length_id_with_fuel(
-    interner: &NodeInterner,
-    rhs: ExprId,
-    span: Span,
-    fuel: u32,
-) -> Result<u128, Option<ResolverError>> {
-    if fuel == 0 {
-        // If we reach here, it is likely from evaluating cyclic globals. We expect an error to
-        // be issued for them after name resolution so issue no error now.
-        return Err(None);
-    }
-
-    match interner.expression(&rhs) {
-        HirExpression::Literal(HirLiteral::Integer(int, false)) => {
-            int.try_into_u128().ok_or(Some(ResolverError::IntegerTooLarge { span }))
-        }
-        HirExpression::Ident(ident, _) => {
-            if let Some(definition) = interner.try_definition(ident.id) {
-                match definition.kind {
-                    DefinitionKind::Global(global_id) => {
-                        let let_statement = interner.get_global_let_statement(global_id);
-                        if let Some(let_statement) = let_statement {
-                            let expression = let_statement.expression;
-                            try_eval_array_length_id_with_fuel(interner, expression, span, fuel - 1)
-                        } else {
-                            Err(Some(ResolverError::InvalidArrayLengthExpr { span }))
-                        }
-                    }
-                    _ => Err(Some(ResolverError::InvalidArrayLengthExpr { span })),
-                }
-            } else {
-                Err(Some(ResolverError::InvalidArrayLengthExpr { span }))
-            }
-        }
-        HirExpression::Infix(infix) => {
-            let lhs = try_eval_array_length_id_with_fuel(interner, infix.lhs, span, fuel - 1)?;
-            let rhs = try_eval_array_length_id_with_fuel(interner, infix.rhs, span, fuel - 1)?;
-
-            match infix.operator.kind {
-                BinaryOpKind::Add => Ok(lhs + rhs),
-                BinaryOpKind::Subtract => Ok(lhs - rhs),
-                BinaryOpKind::Multiply => Ok(lhs * rhs),
-                BinaryOpKind::Divide => Ok(lhs / rhs),
-                BinaryOpKind::Equal => Ok((lhs == rhs) as u128),
-                BinaryOpKind::NotEqual => Ok((lhs != rhs) as u128),
-                BinaryOpKind::Less => Ok((lhs < rhs) as u128),
-                BinaryOpKind::LessEqual => Ok((lhs <= rhs) as u128),
-                BinaryOpKind::Greater => Ok((lhs > rhs) as u128),
-                BinaryOpKind::GreaterEqual => Ok((lhs >= rhs) as u128),
-                BinaryOpKind::And => Ok(lhs & rhs),
-                BinaryOpKind::Or => Ok(lhs | rhs),
-                BinaryOpKind::Xor => Ok(lhs ^ rhs),
-                BinaryOpKind::ShiftRight => Ok(lhs >> rhs),
-                BinaryOpKind::ShiftLeft => Ok(lhs << rhs),
-                BinaryOpKind::Modulo => Ok(lhs % rhs),
-            }
-        }
-        HirExpression::Cast(cast) => {
-            let lhs = try_eval_array_length_id_with_fuel(interner, cast.lhs, span, fuel - 1)?;
-            let lhs_value = Value::Field(lhs.into());
-            let evaluated_value =
-                Interpreter::evaluate_cast_one_step(&cast, rhs, lhs_value, interner)
-                    .map_err(|error| Some(ResolverError::ArrayLengthInterpreter { error }))?;
-
-            evaluated_value
-                .to_u128()
-                .ok_or_else(|| Some(ResolverError::InvalidArrayLengthExpr { span }))
-        }
-        _other => Err(Some(ResolverError::InvalidArrayLengthExpr { span })),
-    }
-}
-
 /// Gives an error if a user tries to create a mutable reference
 /// to an immutable variable.
 fn verify_mutable_reference(interner: &NodeInterner, rhs: ExprId) -> Result<(), ResolverError> {

compiler/noirc_frontend/src/hir/comptime/interpreter.rs

@@ -581,7 +581,7 @@ impl<'local, 'interner> Interpreter<'local, 'interner> {
                             },
                         )?;
 
-                    if let_.comptime || crate_of_global != self.crate_id {
+                    if let_.runs_comptime() || crate_of_global != self.crate_id {
                         self.evaluate_let(let_.clone())?;
                     }
 

compiler/noirc_frontend/src/hir/comptime/value.rs

@@ -1,6 +1,6 @@
 use std::{borrow::Cow, rc::Rc, vec};
 
-use acvm::{AcirField, FieldElement};
+use acvm::FieldElement;
 use im::Vector;
 use iter_extended::{try_vecmap, vecmap};
 use noirc_errors::{Location, Span};
@@ -409,6 +409,9 @@ impl Value {
             Value::Pointer(element, true) => {
                 return element.unwrap_or_clone().into_hir_expression(interner, location);
             }
+            Value::Closure(hir_lambda, _args, _typ, _opt_func_id, _module_id) => {
+                HirExpression::Lambda(hir_lambda)
+            }
             Value::TypedExpr(TypedExpr::StmtId(..))
             | Value::Expr(..)
             | Value::Pointer(..)
@@ -420,7 +423,6 @@ impl Value {
             | Value::Zeroed(_)
             | Value::Type(_)
             | Value::UnresolvedType(_)
-            | Value::Closure(..)
             | Value::ModuleDefinition(_) => {
                 let typ = self.get_type().into_owned();
                 let value = self.display(interner).to_string();
@@ -502,19 +504,28 @@ impl Value {
         Ok(vec![token])
     }
 
-    /// Converts any unsigned `Value` into a `u128`.
-    /// Returns `None` for negative integers.
-    pub(crate) fn to_u128(&self) -> Option<u128> {
+    /// Returns false for non-integral `Value`s.
+    pub(crate) fn is_integral(&self) -> bool {
+        use Value::*;
+        matches!(
+            self,
+            Field(_) | I8(_) | I16(_) | I32(_) | I64(_) | U8(_) | U16(_) | U32(_) | U64(_)
+        )
+    }
+
+    /// Converts any non-negative `Value` into a `FieldElement`.
+    /// Returns `None` for negative integers and non-integral `Value`s.
+    pub(crate) fn to_field_element(&self) -> Option<FieldElement> {
         match self {
-            Self::Field(value) => Some(value.to_u128()),
-            Self::I8(value) => (*value >= 0).then_some(*value as u128),
-            Self::I16(value) => (*value >= 0).then_some(*value as u128),
-            Self::I32(value) => (*value >= 0).then_some(*value as u128),
-            Self::I64(value) => (*value >= 0).then_some(*value as u128),
-            Self::U8(value) => Some(*value as u128),
-            Self::U16(value) => Some(*value as u128),
-            Self::U32(value) => Some(*value as u128),
-            Self::U64(value) => Some(*value as u128),
+            Self::Field(value) => Some(*value),
+            Self::I8(value) => (*value >= 0).then_some((*value as u128).into()),
+            Self::I16(value) => (*value >= 0).then_some((*value as u128).into()),
+            Self::I32(value) => (*value >= 0).then_some((*value as u128).into()),
+            Self::I64(value) => (*value >= 0).then_some((*value as u128).into()),
+            Self::U8(value) => Some((*value as u128).into()),
+            Self::U16(value) => Some((*value as u128).into()),
+            Self::U32(value) => Some((*value as u128).into()),
+            Self::U64(value) => Some((*value as u128).into()),
             _ => None,
         }
     }