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Auto merge of #70831 - sfackler:shrink-future-stack, r=matthewjasper

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Remove a stack frame from .await calls

The stack frames when `.await`ing one async fn from another currently look like this:

```
  12: foo:🅱️:{{closure}}
             at src/main.rs:2
  13: <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll
             at /home/sfackler/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libcore/future/mod.rs:66
  14: core::future::poll_with_context
             at /home/sfackler/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/src/libcore/future/mod.rs:84
  15: foo:🅰️:{{closure}}
             at src/main.rs:6
```

Since the move away from using TLS to pass the Context around, it's now easy to remove frame 14 by removing poll_with_context in favor of calling Future::poll directly. This still leaves the `GenFuture` frame, but that seems significantly harder to deal with.

It also improves diagnostics a bit since they no longer talk about the private poll_with_context function.
This commit is contained in:
bors 2020-04-16 09:13:07 +00:00
commit 4e4d49d60f
5 changed files with 40 additions and 25 deletions
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5
src/test/ui/async-await/issue-70594.stderr
View file

@ -32,11 +32,8 @@ error[E0277]: the trait bound `(): std::future::Future` is not satisfied
|
LL | [1; ().await];
| ^^^^^^^^ the trait `std::future::Future` is not implemented for `()`
|
::: $SRC_DIR/libcore/future/mod.rs:LL:COL
|
LL | F: Future,
| ------ required by this bound in `std::future::poll_with_context`
= note: required by `std::future::Future::poll`
error: aborting due to 5 previous errors

5
src/test/ui/async-await/issues/issue-62009-1.stderr
View file

@ -32,11 +32,8 @@ error[E0277]: the trait bound `[closure@$DIR/issue-62009-1.rs:12:5: 12:15]: std:
|
LL | (|_| 2333).await;
| ^^^^^^^^^^^^^^^^ the trait `std::future::Future` is not implemented for `[closure@$DIR/issue-62009-1.rs:12:5: 12:15]`
|
::: $SRC_DIR/libcore/future/mod.rs:LL:COL
|
LL | F: Future,
| ------ required by this bound in `std::future::poll_with_context`
= note: required by `std::future::Future::poll`
error: aborting due to 4 previous errors