feat(attributes): enable custom attributes

crates/noirc_evaluator/src/ssa/ssa_gen/mod.rs

@@ -130,7 +130,10 @@ impl<'a> FunctionContext<'a> {
                         let slice_contents = self.codegen_array(elements, typ[1].clone());
                         Tree::Branch(vec![slice_length.into(), slice_contents])
                     }
-                    _ => unreachable!("ICE: array literal type must be an array or a slice, but got {}", array.typ),
+                    _ => unreachable!(
+                        "ICE: array literal type must be an array or a slice, but got {}",
+                        array.typ
+                    ),
                 }
             }
             ast::Literal::Integer(value, typ) => {

crates/noirc_frontend/src/ast/function.rs

@@ -86,6 +86,7 @@ impl From<FunctionDefinition> for NoirFunction {
             Some(Attribute::Test) => FunctionKind::Normal,
             Some(Attribute::Oracle(_)) => FunctionKind::Oracle,
             Some(Attribute::Deprecated(_)) | None => FunctionKind::Normal,
+            Some(Attribute::Custom(_)) => FunctionKind::Normal,
         };
 
         NoirFunction { def: fd, kind }

crates/noirc_frontend/src/lexer/lexer.rs

@@ -453,6 +453,15 @@ fn deprecated_attribute_with_note() {
     assert_eq!(token.token(), &Token::Attribute(Attribute::Deprecated("hello".to_string().into())));
 }
 
+#[test]
+fn custom_attribute() {
+    let input = r#"#[custom(hello)]"#;
+    let mut lexer = Lexer::new(input);
+
+    let token = lexer.next().unwrap().unwrap();
+    assert_eq!(token.token(), &Token::Attribute(Attribute::Custom("hello".to_string().into())));
+}
+
 #[test]
 fn test_custom_gate_syntax() {
     let input = "#[foreign(sha256)]#[foreign(blake2s)]#[builtin(sum)]";

crates/noirc_frontend/src/lexer/token.rs

@@ -326,6 +326,7 @@ pub enum Attribute {
     Oracle(String),
     Deprecated(Option<String>),
     Test,
+    Custom(String),
 }
 
 impl fmt::Display for Attribute {
@@ -337,6 +338,7 @@ impl fmt::Display for Attribute {
             Attribute::Test => write!(f, "#[test]"),
             Attribute::Deprecated(None) => write!(f, "#[deprecated]"),
             Attribute::Deprecated(Some(ref note)) => write!(f, r#"#[deprecated("{note}")]"#),
+            Attribute::Custom(ref k) => write!(f, "#[{k}]"),
         }
     }
 }
@@ -390,6 +392,10 @@ impl Attribute {
                 Attribute::Deprecated(name.trim_matches('"').to_string().into())
             }
             ["test"] => Attribute::Test,
+            [name] => {
+                validate(name)?;
+                Attribute::Custom(name.to_string())
+            }
             _ => {
                 return Err(LexerErrorKind::MalformedFuncAttribute { span, found: word.to_owned() })
             }
@@ -429,6 +435,7 @@ impl AsRef<str> for Attribute {
             Attribute::Oracle(string) => string,
             Attribute::Deprecated(Some(string)) => string,
             Attribute::Test | Attribute::Deprecated(None) => "",
+            Attribute::Custom(string) => string,
         }
     }
 }