debug_println! doesn't work in #[ink(constructor)]

[cmichi]

To reproduce one can use the contract-transfer example. Just modify the constructor in this way:

/// Creates a new instance of this contract.
#[ink(constructor)]
pub fn new() -> Self {
    ink_env::debug_println!("constructor!");
    Self {}
}

Start the canvas-node this way:

$ canvas --tmp --dev -lerror,runtime::contracts=debug

If you deploy and interact with the contract the debug_println!'s in the #[ink(message)]'s will show up on the console, but not the one from the constructor.

Note that #820 needs to be merged to reproduce this.

[Robbepop]

Might it be possible that this is not an ink! related issue but resides in the contracts pallet instead? I cannot see a reason atm why constructors and messages would behave different in ink!. Do you?

[cmichi]

Nope, it was also my intuition that an investigation would probably lead to the contracts pallet. I haven't looked deeper though.

Does @athei maybe have an immediate hunch if this could be caused by the contracts pallet?

[athei]

AFAIK no UI dry-runs the constructor as RPC before deploying. Remember: Debugging is not enabled during on-chain execution. Only during RPC calls.

[cmichi]

Ok, but in principle it's possible to do a dry-run of the constructor, right? Then I would create follow-ups for the UI's.

[athei]

Yes. This functionality was added somewhat recently.

[cmichi]

Things left to do for this ticket:

• Test if this bug still appears when instantiating a contract with cargo contract instantiate.
• Test if it still happens with polkadot-js.
• Test if it still happens with contracts-ui.

If it happens in none of those we can close this issue.

[SkymanOne]

Closing as the bug no longer appears on ink! 4.1