Cross-Contract Calls and Events don't work (ink 4.2.1)

Question

I have replicate this error using the MultiContractCaller from the ink-examples

In the multi_contract_caller we have a FakeEvent.

#[ink(event)]
pub struct FakeEvent {
    account_id: AccountId,
}

Which is being emitted in the multi_contract_caller change

#[ink(message)]
pub fn change(&mut self, by: i32) {
     let caller = self.env().caller();
     self.env().emit_event(FakeEvent { account_id: caller });
     match self.which {
           Which::Adder => self.adder.inc(by),
           Which::Subber => self.subber.dec(by),
    }
}

---

---

---

In the accumulator we have another FakeEvent.

#[ink(event)]
pub struct FakeEvent {
    account_id: AccountId,
}

Which is being emitted in the accumulator inc

#[ink(message)]
pub fn inc(&mut self, by: i32) {
       let caller = self.env().caller();
       self.env().emit_event(FakeEvent { account_id: caller });
       self.value += by;
}

In theory this should have been solved by the "Events 2.0"

But the result is this below. Nevertheless, anyone knows why or what magic trick should I do to make this work?

error[E0284]: type annotations needed
   --> /home/projects/crap/ink-examples-main/multi_contract_caller/lib.rs:101:24
    |
101 |             self.env().emit_event(FakeEvent { account_id: caller });
    |                        ^^^^^^^^^^
    |
    = note: cannot satisfy `<_ as ContractEventBase>::Type == _`
help: try using a fully qualified path to specify the expected types
    |
101 |             <EnvAccess<'_, DefaultEnvironment> as EmitEvent<C>>::emit_event::<FakeEvent>(self.env(), FakeEvent { account_id: caller });
    |             +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++          ~

error[E0283]: type annotations needed
   --> /home/projects/crap/ink-examples-main/multi_contract_caller/lib.rs:101:24
    |
101 |             self.env().emit_event(FakeEvent { account_id: caller });
    |                        ^^^^^^^^^^
    |
note: multiple `impl`s satisfying `EnvAccess<'_, DefaultEnvironment>: EmitEvent<_>` found
   --> /home/projects/crap/ink-examples-main/multi_contract_caller/lib.rs:3:1
    |
3   | #[ink::contract]
    | ^^^^^^^^^^^^^^^^
    = note: and another `impl` found in the `accumulator` crate: `impl<'a> EmitEvent<Accumulator> for EnvAccess<'a, <Accumulator as ContractEnv>::Env>;`
    = note: this error originates in the attribute macro `ink::contract` (in Nightly builds, run with -Z macro-backtrace for more info)
help: try using a fully qualified path to specify the expected types
    |
101 |             <EnvAccess<'_, DefaultEnvironment> as EmitEvent<C>>::emit_event::<FakeEvent>(self.env(), FakeEvent { account_id: caller });
    |             +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++          ~

Some errors have detailed explanations: E0283, E0284.
For more information about an error, try `rustc --explain E0283`.
error: could not compile `multi_contract_caller` (bin "multi_contract_caller") due to 2 prevERROR: command ["/home/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/bin/cargo", "build", "--color=always", "--target=wasm32-unknown-unknown", "-Zbuild-std=core,alloc", "--no-default-features", "--release", "--target-dir=/home/projects/crap/ink-examples-main/multi_contract_caller/target/ink", "-Zbuild-std-features=panic_immediate_abort"] exited with code 101

Whit this bug there are at least two other posts:

Post I

Post II

Answer 1

Why don't you do exactly what error message states? Replace

self.env().emit_event(FakeEvent { account_id: caller });

with

use ink::{
  codegen::EmitEvent,
  env::DefaultEnvironment,
  EnvAccess,
};

<EnvAccess<'_, DefaultEnvironment> as EmitEvent<MultiContractCaller>>::emit_event::<FakeEvent>(
  self.env(),
  FakeEvent { account_id: caller },
);

I am not sure why error happened but following error message instructions helped me to solve the same error in contract I wrote some time ago.