Write a version of assert which allows a msg to be passed to the simulator

[iAmMichaelConnor]

At the moment, assert(condition) doesn't enable an error message to be given.

assert(condition, error_msg) would be lovely.

Now, I'm not sure if this is an issue that should be opened in the noir-lang repo, or if this is something we'll need to implement ourselves, to enable to the error message to be passed directly to the simulator via an oracle call.

E.g. we could create a wrapper function contract_assert(condition, error_msg), which under the hood does an assert(condition) and then does an oracle call with the message?

Tagging @sirasistant for inspirational ideas :)

[sirasistant]

I think that given the fact that we now have stepwise execution of ACIR we could just create a wrapper assert fn that if the condition is false calls an oracle with the message and then asserts the condition, and it would work fine for aztec (although It could be a bit inefficient), receiving the oracle call and then failing. But this could be much easier if the acir expressions could just have a message attached in case they fail.
The only advantage of this method over #1224 is for the case where we don't have access to the source code of the contract. It might be valuable even for regular noir. Will discuss with the noir team!

[iAmMichaelConnor]

although It could be a bit inefficient

Why would this be inefficient?

The only advantage of this method over #1224 is for the case where we don't have access to the source code of the contract

Yeah, it was that discussion that made me open this issue. Distributing source code isn't guaranteed (although validation of source code against bytecode should be encouraged, of course). Distributing the bytecode is guaranteed.

[sirasistant]

Why would this be inefficient?

For every assert with message you'll end up with two opcodes, the expression itself and a brillig opcode to send the message just before. But It would be only executed in the case of failure which should be ok

[sirasistant]

This issue is being worked on the noir side in this issue noir-lang/noir#1939

[sirasistant]

Done in #1997
both assert and assert_eq support an optional literal string parameter now