I was using substrate-node-template, and created some benchmarking functions.

I was able to use bounded_vec macro in tests.rs but, can't able to use it in the benchmarking.rs file

my code

#![cfg(feature = "runtime-benchmarks")]
use super::*;

use crate::Pallet as Template;
use frame_benchmarking::v2::*;
use frame_support::bounded_vec;
use frame_system::RawOrigin;

mod benchmarks {
    use super::*;

    fn store() {
        let caller: T::AccountId = whitelisted_caller();
            bounded_vec![Types{ key: b"1".to_vec().try_into().unwrap(), is_accepted: false }],
    impl_benchmark_test_suite!(Template, crate::mock::new_test_ext(), crate::mock::Test);

it was working fine when trying to compile cargo t -p pallet-template -F runtime-benchmarks

but, it was throwing errors while trying to compile with cargo t -p node-template-runtime -F runtime-benchmarks


error: cannot determine resolution for the macro `bounded_vec`
   --> /mnt/c/Users/pavan/PROJECTS/substrate-node-template/pallets/template/src/benchmarking.rs:24:4
 24 |             bounded_vec![Types{ key: b"1".to_vec().try_into().unwrap(), is_accepted: false }],
  • Try importing it like this: use sp_runtime::bounded_vec;
    – Alex Bean
    Commented Oct 4, 2023 at 7:28
  • I have tried using it but again triggers another error error[E0432]: unresolved import sp_runtime`` --> pallets/template/src/benchmarking.rs:9:5 | 9 | use sp_runtime::bounded_vec; | ^^^^^^^^^^ help: a similar path exists: frame_support::sp_runtime`` `
    – Mojo
    Commented Oct 4, 2023 at 10:18
  • @AlexBean can you pls help me out
    – Mojo
    Commented Oct 4, 2023 at 13:27

2 Answers 2


The bounded_vec macro is only available in std context - and therefore not in benchmarks.
You can replace it with vec![ ... ].try_into().unwrap().
It was done this way since it hides an unwrap, which could cause a panic in your runtime code. So it is hidden behind the std feature.


Not sure why the bounded_vec import is not working, see an example in the Substrate repo.

However I am not sure you are doing the conversion to bounded_vec propertly anyway as you can't just do a cast from a Vec into a BoundedVec.

See this way of doing it: How to create a bounded vec from a normal vec?. In your case it will look something like that:

use frame_support::BoundedVec;

let your_bounded_vec = BoundedVec::<u8, ConstU32<5>>::try_from(your_unbounded_vec);

See another example in this previous StackExchange answer: frame_benchmarking convert Vec to BoundedVec

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