Mazdak Farrokhzad Centril

Centril's views on the "Await Syntax Write Up"

in our opinion this — which we will call the "error handling problem” — remains the primary problem that we are trying to resolve.

I don't agree that this is the primary problem; it's one of many problems to resolve; Chaining (and thus not forcing temporaries), general composability, and working well with IDEs is among notable problems.

Syntactic Sugar Solution:

I think it is a stretch to call this syntactic sugar in the first place. The syntax await? is composing await + ?. In my view this is not enough semantic compression to be deserving of the description "syntactic sugar".

Error Index

E0001

This error occurs when #[derive(Arbitrary)] is used on a type which has any lifetime parameters. For example:

Given the following type definitions:

struct Foo(usize);

struct Wrapping<T>(T);

struct Product<A, B>(A, B);

trait Trait { type Assoc; }

	// compile-fail

	#![feature(associated_type_bounds)]

	use std::fmt::Debug;

	trait Lam<Binder> { type App; }

	fn nested_bounds<_0, _1, _2, D>()
	where

	centril@centrilnas2:~/programming/rust$ RUST_BACKTRACE=1 ./x.py -i build --stage 1 [485/723]
	Updating only changed submodules
	Submodules updated in 0.02 seconds
	Finished dev [unoptimized] target(s) in 0.20s
	Building stage0 std artifacts (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
	Finished release [optimized] target(s) in 0.21s
	Copying stage0 std from stage0 (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu / x86_64-unknown-linux-gnu)
	Building stage0 test artifacts (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
	Finished release [optimized] target(s) in 0.18s
	Copying stage0 test from stage0 (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu / x86_64-unknown-linux-gnu)

	// run-pass

	// The purpose of this test is to demonstrate that so long as no more than the
	// first expanded trait in dyn Bound is an auto-trait, it's all good.

	#![feature(trait_alias)]

	fn main() {}

	trait _0 = Send + Sync;

	// run-pass

	use core::fmt::Debug;
	use core::iter::{Empty, Once};
	use core::ops::Range;

	trait Lam<Binder> { type App; }

	#[derive(Clone)]
	struct L1;

	Updating only changed submodules
	Submodules updated in 0.01 seconds
	Building stage0 tool tidy (x86_64-unknown-linux-gnu)
	tidy check
	* 565 error codes
	* highest error code: E0722
	* 250 features
	Building stage0 std artifacts (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
	Copying stage0 std from stage0 (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu / x86_64-unknown-linux-gnu)
	Building stage0 test artifacts (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)

	// run-pass

	struct Foo<T>(T);
	struct Bar<T> { x: T }
	struct W(u32);
	struct A { a: u32 }

	const fn basics((a,): (u32,)) -> u32 {
	// Deferred assignment:
	let b: u32;


	// while P { B_1 } else { B_2 } */
	// ==>
	/*
	if P {
	B_1;

	while P {
	B_1
	}