fix!: disallow specifying associated items via generics

compiler/noirc_frontend/src/elaborator/mod.rs

@@ -2192,9 +2192,35 @@ impl<'context> Elaborator<'context> {
 
             let (trait_id, mut trait_generics, path_location) = match &trait_impl.r#trait.typ {
                 UnresolvedTypeData::Named(trait_path, trait_generics, _) => {
+                    let mut trait_generics = trait_generics.clone();
                     let location = trait_path.location;
                     let trait_path = self.validate_path(trait_path.clone());
                     let trait_id = self.resolve_trait_by_path(trait_path);
+
+                    // Check and remove and any generic that is specifying an associated item
+                    if !trait_generics.named_args.is_empty() {
+                        if let Some(trait_id) = trait_id {
+                            let associated_types =
+                                self.interner.get_trait(trait_id).associated_types.clone();
+                            trait_generics.named_args.retain(|(name, typ)| {
+                                let associated_type = associated_types.iter().find(|associated_type| {
+                                    associated_type.name.as_str() == name.as_str()
+                                });
+                                if associated_type.is_some() {
+                                    let location = name.location().merge(typ.location);
+                                    self.push_err(
+                                        ResolverError::AssociatedItemConstraintsNotAllowedInGenerics {
+                                            location,
+                                        },
+                                    );
+                                    false
+                                } else {
+                                    true
+                                }
+                            });
+                        }
+                    }
+
                     (trait_id, trait_generics.clone(), location)
                 }
                 UnresolvedTypeData::Resolved(quoted_type_id) => {

compiler/noirc_frontend/src/hir/resolution/errors.rs

@@ -178,6 +178,8 @@ pub enum ResolverError {
     UnconstrainedTypeParameter { ident: Ident },
     #[error("Unreachable statement")]
     UnreachableStatement { location: Location, break_or_continue_location: Location },
+    #[error("Associated item constraints are not allowed here")]
+    AssociatedItemConstraintsNotAllowedInGenerics { location: Location },
 }
 
 impl ResolverError {
@@ -237,7 +239,10 @@ impl ResolverError {
             | ResolverError::FoldAttributeOnUnconstrained { location, .. }
             | ResolverError::OracleMarkedAsConstrained { location, .. }
             | ResolverError::LowLevelFunctionOutsideOfStdlib { location }
-            | ResolverError::UnreachableStatement { location, .. } => *location,
+            | ResolverError::UnreachableStatement { location, .. }
+            | ResolverError::AssociatedItemConstraintsNotAllowedInGenerics { location } => {
+                *location
+            }
             ResolverError::UnusedVariable { ident }
             | ResolverError::UnusedItem { ident, .. }
             | ResolverError::DuplicateField { field: ident }
@@ -748,6 +753,13 @@ impl<'a> From<&'a ResolverError> for Diagnostic {
                 diagnostic.add_secondary("Any code following this expression is unreachable".to_string(), *break_or_continue_location);
                 diagnostic
             }
+            ResolverError::AssociatedItemConstraintsNotAllowedInGenerics { location} => {
+                Diagnostic::simple_error(
+                    "Associated item constraints are not allowed here".to_string(),
+                    "Consider removing this associated item binding".to_string(),
+                    *location,
+                )
+            }
         }
     }
 }

noir_stdlib/src/hash/mod.nr

@@ -183,10 +183,12 @@ pub trait BuildHasher {
 
 pub struct BuildHasherDefault<H>;
 
-impl<H> BuildHasher<H = H> for BuildHasherDefault<H>
+impl<H> BuildHasher for BuildHasherDefault<H>
 where
     H: Hasher + Default,
 {
+    type H = H;
+
     fn build_hasher(_self: Self) -> H {
         H::default()
     }

test_programs/compile_failure/associated_type_in_impl_trait_generic/Nargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "associated_type_in_impl_trait_generic"
+type = "bin"
+authors = [""]
+compiler_version = ">=0.33.0"
+
+[dependencies]

test_programs/compile_failure/associated_type_in_impl_trait_generic/src/main.nr

@@ -0,0 +1,8 @@
+trait Trait {
+    type T;
+}
+
+impl Trait<T = i32> for bool {
+}
+
+fn main() {}