feat: Derive Eq & Default

noir_stdlib/src/cmp.nr

@@ -1,9 +1,37 @@
+use crate::meta::derive_via;
+
+#[derive_via(derive_eq)]
 // docs:start:eq-trait
 trait Eq {
     fn eq(self, other: Self) -> bool;
 }
 // docs:end:eq-trait
 
+comptime fn derive_eq(s: StructDefinition) -> Quoted {
+    let typ = s.as_type();
+
+    let impl_generics = s.generics().join(quote {,});
+
+    let where_clause = s.generics().map(|name| quote { $name: Default }).join(quote {,});
+
+    // `(self.a == other.a) & (self.b == other.b) & ...`
+    let equalities = s.fields().map(
+        |f: (Quoted, Type)| {
+        let name = f.0;
+        quote { (self.$name == other.$name) }
+    }
+    );
+    let body = equalities.join(quote { & });
+
+    quote {
+        impl<$impl_generics> Eq for $typ where $where_clause {
+            fn eq(self, other: Self) -> bool {
+                $body
+            }
+        }
+    }
+}
+
 impl Eq for Field { fn eq(self, other: Field) -> bool { self == other } }
 
 impl Eq for u64 { fn eq(self, other: u64) -> bool { self == other } }

noir_stdlib/src/default.nr

@@ -1,9 +1,37 @@
+use crate::meta::derive_via;
+
+#[derive_via(derive_default)]
 // docs:start:default-trait
 trait Default {
     fn default() -> Self;
 }
 // docs:end:default-trait
 
+comptime fn derive_default(s: StructDefinition) -> Quoted {
+    let typ = s.as_type();
+
+    let impl_generics = s.generics().join(quote {,});
+
+    let where_clause = s.generics().map(|name| quote { $name: Default }).join(quote {,});
+
+    // `foo: Default::default(), bar: Default::default(), ...`
+    let fields = s.fields().map(
+        |f: (Quoted, Type)| {
+        let name = f.0;
+        quote { $name: Default::default() }
+    }
+    );
+    let fields = fields.join(quote {,});
+
+    quote {
+        impl<$impl_generics> Default for $typ where $where_clause {
+            fn default() -> Self {
+                Self { $fields }
+            }
+        }
+    }
+}
+
 impl Default for Field { fn default() -> Field { 0 } }
 
 impl Default for u8 { fn default() -> u8 { 0 } }

noir_stdlib/src/hash/poseidon2.nr

@@ -1,7 +1,7 @@
 use crate::hash::Hasher;
 use crate::default::Default;
 
-global RATE: u32 = 3;
+comptime global RATE: u32 = 3;
 
 struct Poseidon2 {
     cache: [Field;3],

noir_stdlib/src/meta/mod.nr

@@ -2,9 +2,9 @@ use crate::collections::umap::UHashMap;
 use crate::hash::BuildHasherDefault;
 use crate::hash::poseidon2::Poseidon2Hasher;
 
+mod struct_def;
 mod trait_constraint;
 mod trait_def;
-mod type_def;
 mod quoted;
 
 /// Calling unquote as a macro (via `unquote!(arg)`) will unquote

test_programs/execution_success/derive/src/main.nr

@@ -19,7 +19,17 @@ comptime fn derive_do_nothing(s: StructDefinition) -> Quoted {
     }
 }
 
+// Test stdlib derive fns & multiple traits
+#[derive(Eq, Default)]
+struct MyOtherStruct {
+    field1: u32,
+    field2: u64,
+}
+
 fn main() {
     let s = MyStruct { my_field: 1 };
     s.do_nothing();
+
+    let o = MyOtherStruct::default();
+    assert_eq(o, o);
 }