chore: add regression tests for #4372 (#6401)

compiler/noirc_frontend/src/tests.rs

@@ -3548,17 +3548,27 @@ fn uses_self_in_import() {
 }
 
 #[test]
-fn alias_in_let_pattern() {
+fn does_not_error_on_return_values_after_block_expression() {
+    // Regression test for https://github.com/noir-lang/noir/issues/4372
     let src = r#"
-        struct Foo<T> { x: T }
-
-        type Bar<U> = Foo<U>;
+    fn case1() -> [Field] {
+        if true {
+        }
+        &[1]
+    }
 
-        fn main() {
-            let Bar { x } = Foo { x: [0] };
-            // This is just to show the compiler knows this is an array.
-            let _: [Field; 1] = x;
+    fn case2() -> [u8] {
+        let mut var: u8 = 1;
+        {
+            var += 1;
         }
+        &[var]
+    }
+
+    fn main() {
+        let _ = case1();
+        let _ = case2();
+    }
     "#;
     assert_no_errors(src);
 }

compiler/noirc_frontend/src/tests/aliases.rs

@@ -31,3 +31,19 @@ fn allows_usage_of_type_alias_as_return_type() {
     "#;
     assert_no_errors(src);
 }
+
+#[test]
+fn alias_in_let_pattern() {
+    let src = r#"
+        struct Foo<T> { x: T }
+
+        type Bar<U> = Foo<U>;
+
+        fn main() {
+            let Bar { x } = Foo { x: [0] };
+            // This is just to show the compiler knows this is an array.
+            let _: [Field; 1] = x;
+        }
+    "#;
+    assert_no_errors(src);
+}