impl compare nested array types method for function return type

compiler/src/statement/return_/return_.rs

@@ -30,6 +30,8 @@ fn check_return_type(expected: Option<Type>, actual: Type, span: Span) -> Result
             if expected.ne(&actual) {
                 if expected.is_self() && actual.is_circuit() {
                     return Ok(());
+                } else if expected.match_array_types(&actual) {
+                    return Ok(());
                 } else {
                     return Err(StatementError::arguments_type(&expected, &actual, span));
                 }

compiler/src/value/value.rs

@@ -108,9 +108,9 @@ impl<F: Field + PrimeField, G: GroupType<F>> ConstrainedValue<F, G> {
             ConstrainedValue::Integer(integer) => Type::IntegerType(integer.get_type()),
 
             // Data type wrappers
-            ConstrainedValue::Array(types) => {
+            ConstrainedValue::Array(array) => {
-                let array_type = types[0].to_type(span.clone())?;
+                let array_type = array[0].to_type(span.clone())?;
-                let mut dimensions = vec![types.len()];
+                let mut dimensions = vec![array.len()];
 
                 // Nested array type
                 if let Type::Array(inner_type, inner_dimensions) = &array_type {

compiler/tests/function/mod.rs

@@ -141,3 +141,37 @@ fn test_value_unchanged() {
 
     assert_satisfied(program);
 }
+
+// Test return multidimensional arrays
+
+#[test]
+fn test_return_array_nested_fail() {
+    let bytes = include_bytes!("return_array_nested_fail.leo");
+    let program = parse_program(bytes).unwrap();
+
+    expect_compiler_error(program);
+}
+
+#[test]
+fn test_return_array_nested_pass() {
+    let bytes = include_bytes!("return_array_nested_pass.leo");
+    let program = parse_program(bytes).unwrap();
+
+    assert_satisfied(program);
+}
+
+#[test]
+fn test_return_array_tuple_fail() {
+    let bytes = include_bytes!("return_array_tuple_fail.leo");
+    let program = parse_program(bytes).unwrap();
+
+    expect_compiler_error(program);
+}
+
+#[test]
+fn test_return_array_tuple_pass() {
+    let bytes = include_bytes!("return_array_tuple_pass.leo");
+    let program = parse_program(bytes).unwrap();
+
+    assert_satisfied(program);
+}

compiler/tests/function/return_array_nested_fail.leo

@@ -0,0 +1,7 @@
+function array_3x2_tuple() -> [[u8; 2]; 3] {
+    return [0u8; (2, 3)] // The correct 3x2 array tuple is `[0u8; (3, 2)]`
+}
+
+function main() {
+    let b = array_3x2_tuple();
+}

compiler/tests/function/return_array_nested_pass.leo

@@ -0,0 +1,12 @@
+function array_3x2_nested() -> [[u8; 2]; 3] {
+    return [[0u8; 2]; 3]
+}
+
+function array_3x2_tuple() -> [[u8; 2]; 3] {
+    return [0u8; (3, 2)]
+}
+
+function main() {
+    let a = array_3x2_nested();
+    let b = array_3x2_tuple();
+}

compiler/tests/function/return_array_tuple_fail.leo

@@ -0,0 +1,7 @@
+function array_3x2_nested() -> [u8; (3, 2)] {
+    return [[0u8; 3]; 2] // The correct 3x2 nested array is `[0u8; 2]; 3]`
+}
+
+function main() {
+    let a = array_3x2_nested();
+}

compiler/tests/function/return_array_tuple_pass.leo

@@ -0,0 +1,12 @@
+function array_3x2_nested() -> [u8; (3, 2)] {
+    return [[0u8; 2]; 3]
+}
+
+function array_3x2_tuple() -> [u8; (3, 2)] {
+    return [0u8; (3, 2)]
+}
+
+function main() {
+    let a = array_3x2_nested();
+    let b = array_3x2_tuple();
+}

typed/src/types/type_.rs

@@ -58,6 +58,26 @@ impl Type {
         false
     }
 
+    pub fn match_array_types(&self, other: &Type) -> bool {
+        // Check that both `self` and `other` are of type array
+        let (type_1, dimensions_1) = match self {
+            Type::Array(type_, dimensions) => (type_, dimensions),
+            _ => return false,
+        };
+
+        let (type_2, dimensions_2) = match other {
+            Type::Array(type_, dimensions) => (type_, dimensions),
+            _ => return false,
+        };
+
+        // Expand multidimensional array syntax
+        let (type_1_expanded, dimensions_1_expanded) = expand_array_type(type_1, dimensions_1);
+        let (type_2_expanded, dimensions_2_expanded) = expand_array_type(type_2, dimensions_2);
+
+        // Return true if expanded array types and dimensions match
+        type_1_expanded.eq(&type_2_expanded) && dimensions_1_expanded.eq(&dimensions_2_expanded)
+    }
+
     pub fn outer_dimension(&self, dimensions: &Vec<usize>) -> Self {
         let type_ = self.clone();
 
@@ -85,6 +105,19 @@ impl Type {
     }
 }
 
+fn expand_array_type(type_: &Type, dimensions: &Vec<usize>) -> (Type, Vec<usize>) {
+    if let Type::Array(nested_type, nested_dimensions) = type_ {
+        // Expand nested array type
+        let mut expanded_dimensions = dimensions.clone();
+        expanded_dimensions.append(&mut nested_dimensions.clone());
+
+        return expand_array_type(nested_type, &expanded_dimensions);
+    } else {
+        // Array type is fully expanded
+        (type_.clone(), dimensions.clone())
+    }
+}
+
 /// pest ast -> Explicit Type for defining circuit members and function params
 
 impl From<DataType> for Type {