The call_builder macro to provide a more developer-friendly way to work with CallBuilder

[xgreenx]

Overview

Implemented the call_builder! macro from the proposal.

The macro return the CallBuilder type that supports hinting and highlighting in the IDE.
The usage is the same as for standard cross-contract calls, where the call is wrapped into the call_builder macro:

#[ink::trait_definition]
pub trait Increment {
    /// Increments the current value of the implementer by one (1).
    #[ink(message)]
    fn inc_by_delta(&mut self, delta_1: u64, delta_2: u32);

    /// Returns the current value of the implementer.
    #[ink(message)]
    fn get(&self) -> u64;
}

#[ink(message)]
fn get(&self) -> u64 {
    self.incrementer.get();
    call_builder!(self.incrementer.get()).invoke();
    call_builder!(::dyn_traits::Increment::get(&self.incrementer)).invoke();
    call_builder!(<_ as ::dyn_traits::Increment>::get(&self.incrementer))
        .invoke();
    call_builder!(Increment::get(&self.incrementer)).invoke();
    call_builder!(::dyn_traits::Increment::get(&self.incrementer)).invoke();

    call_builder!(self.incrementer().get()).invoke()
}

#[ink(message)]
fn inc_by_delta(&mut self, delta_1: u64, delta_2: u32) -> u64 {
    self.incrementer.inc_by_delta(delta_1, delta_2);
    call_builder!(self.incrementer.inc_by_delta(delta_1, delta_2)).invoke();
    call_builder!(::dyn_traits::Increment::inc_by_delta(&mut self.incrementer, delta_1, delta_2)).invoke();
    call_builder!(<_ as ::dyn_traits::Increment>::inc_by_delta(&mut self.incrementer, delta_1, delta_2))
        .invoke();
    call_builder!(Increment::inc_by_delta(&mut self.incrementer, delta_1, delta_2)).invoke();
    call_builder!(::dyn_traits::Increment::inc_by_delta(&mut self.incrementer, delta_1, delta_2)).invoke();
    let call_builder =
        call_builder!(self.incrementer.inc_by_delta(delta_1, delta_2));

    call_builder.invoke()
}

How it looks in the IDE:

Follow-up

• In the same way, we can add the create_builder! macro for constructors in the follow-up PR. It would simplify instantiation because all functions will be highlighted. The macro would be much simpler because it always requires an explicit type name.
• Add mesage_descriptor! macro that returns the MessageDescription. Everyone would be able to get the method's selector(and other properties of the message) like in the solidity message_descriptor!(self.balanec_of).selector().
• Remove the TraitCallBuilder and replace its functionality with a new macro. Remove the {method_ident}Output associated type from the trait definition.

[SkymanOne]

I am not fun of the macro's interface. Wrapping every single call into the macro just to get the syntax highlighting for the .invoke() or .try_invoke() commands doesn't seem very idiomatic IMHO.

Perhaps, if we could do something like:

self.incrementer.get().invoke()

It would be much clearer to the developer. I am open to other proposals too.

[xgreenx]

It is a syntax for a rare case when the developers need to work with a result of the cross-contract call. Primarily, you work with methods directly like self.incrementer.get().

The idea of this change is to remove the {method_ident}Output alias from the trait in the follow-up PR. So it is impossible to support self.incrementer.get().invoke().

[cmichi]

I'm closing the PR for now, but we might revisit this approach. later.

[codecov]

Codecov Report

Attention: Patch coverage is 21.73913% with 18 lines in your changes missing coverage. Please review.

Project coverage is 52.92%. Comparing base (a51abe3) to head (ec7e669).
Report is 373 commits behind head on master.

Files with missing lines	Patch %	Lines
.../ink/codegen/src/generator/trait_def/definition.rs	0.00%	8 Missing ⚠️
...odegen/src/generator/as_dependency/contract_ref.rs	0.00%	5 Missing ⚠️
crates/ink/src/reflect/message.rs	55.55%	4 Missing ⚠️
crates/e2e/macro/src/codegen.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1858      +/-   ##
==========================================
- Coverage   53.00%   52.92%   -0.09%     
==========================================
  Files         212      213       +1     
  Lines        6724     6744      +20     
==========================================
+ Hits         3564     3569       +5     
- Misses       3160     3175      +15     

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