Improve async-await/generator obligation errors in some cases #70679

tmandry · 2020-04-02T02:09:43Z

This change is best read one commit at a time (I add a test at the beginning and update it in each change after).

The test2 function is a case I found while writing the test that we don't handle with this code yet. I don't attempt to fix it in this PR, but it's a good candidate for future work.

r? @davidtwco, @nikomatsakis

src/librustc_trait_selection/traits/error_reporting/suggestions.rs

nikomatsakis

Generally looks good. Left some thoughts.

src/test/ui/async-await/async-fn-nonsend.stderr

src/test/ui/async-await/issue-68112.stderr

src/librustc_trait_selection/traits/error_reporting/suggestions.rs

davidtwco · 2020-04-08T10:09:20Z

r? @nikomatsakis

tmandry · 2020-04-08T19:03:31Z

@nikomatsakis I updated the wording, what do you think? It's a little repetitive in some places, but by and large I think it's for the best.

nikomatsakis

I think these are looking much better, yes.

nikomatsakis · 2020-04-10T19:17:44Z

src/test/ui/generator/issue-68112.stderr

+   = help: the trait `std::marker::Sync` is not implemented for `std::cell::RefCell<i32>`
+   = note: required because of the requirements on the impl of `std::marker::Send` for `std::sync::Arc<std::cell::RefCell<i32>>`
+   = note: required because it appears within the type `[generator@$DIR/issue-68112.rs:38:5: 41:6 t:std::sync::Arc<std::cell::RefCell<i32>> {()}]`
+   = note: required because it appears within the type `impl std::ops::Generator`


this backtrace is confusing, but that's a separate issue I think =)

nikomatsakis · 2020-04-10T19:18:07Z

src/test/ui/async-await/issue-67252-unnamed-future.stderr

@@ -5,14 +5,14 @@ LL | fn spawn<T: Send>(_: T) {}
   |    -----    ---- required by this bound in `spawn`
 ...
 LL |     spawn(async {
-   |     ^^^^^ future is not `Send`
+   |     ^^^^^ future created by async block is not `Send`


seems good to me

nikomatsakis · 2020-04-10T19:20:00Z

@bors r+

bors · 2020-04-10T19:20:02Z

📌 Commit 889cfe1 has been approved by nikomatsakis

@davidtwco

Improve async-await/generator obligation errors in some cases Fixes rust-lang#68112. This change is best read one commit at a time (I add a test at the beginning and update it in each change after). The `test2` function is a case I found while writing the test that we don't handle with this code yet. I don't attempt to fix it in this PR, but it's a good candidate for future work. r? @davidtwco, @nikomatsakis

bors · 2020-04-12T10:02:11Z

🔒 Merge conflict

This pull request and the master branch diverged in a way that cannot be automatically merged. Please rebase on top of the latest master branch, and let the reviewer approve again.

How do I rebase?

Assuming self is your fork and upstream is this repository, you can resolve the conflict following these steps:

git checkout issue-68112 (switch to your branch)
git fetch upstream master (retrieve the latest master)
git rebase upstream/master -p (rebase on top of it)
Follow the on-screen instruction to resolve conflicts (check git status if you got lost).
git push self issue-68112 --force-with-lease (update this PR)

You may also read Git Rebasing to Resolve Conflicts by Drew Blessing for a short tutorial.

Please avoid the "Resolve conflicts" button on GitHub. It uses git merge instead of git rebase which makes the PR commit history more difficult to read.

Sometimes step 4 will complete without asking for resolution. This is usually due to difference between how Cargo.lock conflict is handled during merge and rebase. This is normal, and you should still perform step 5 to update this PR.

Error message

Auto-merging src/test/ui/generator/not-send-sync.stderr
Auto-merging src/test/ui/async-await/issues/issue-65436-raw-ptr-not-send.stderr
Auto-merging src/test/ui/async-await/issue-67252-unnamed-future.stderr
Auto-merging src/test/ui/async-await/issue-64130-non-send-future-diags.stderr
Auto-merging src/test/ui/async-await/issue-64130-3-other.stderr
Auto-merging src/test/ui/async-await/issue-64130-2-send.stderr
Auto-merging src/test/ui/async-await/issue-64130-1-sync.stderr
Auto-merging src/test/ui/async-await/async-fn-nonsend.stderr
Auto-merging src/librustc_typeck/check/expr.rs
Auto-merging src/librustc_trait_selection/traits/error_reporting/suggestions.rs
CONFLICT (content): Merge conflict in src/librustc_trait_selection/traits/error_reporting/suggestions.rs
Automatic merge failed; fix conflicts and then commit the result.

bors · 2020-04-12T10:11:18Z

☔ The latest upstream changes (presumably #69707) made this pull request unmergeable. Please resolve the merge conflicts.

I personally find this clearer.

tmandry · 2020-04-14T02:15:01Z

@bors r=nikomatsakis

bors · 2020-04-14T02:15:02Z

📌 Commit 4326d95 has been approved by nikomatsakis

bors · 2020-04-14T06:47:43Z

⌛ Testing commit 4326d95 with merge a3ef360...

bors · 2020-04-14T10:04:40Z

☀️ Test successful - checks-azure
Approved by: nikomatsakis
Pushing a3ef360 to master...

rust-highfive assigned davidtwco Apr 2, 2020

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Apr 2, 2020

tmandry force-pushed the issue-68112 branch from d41f7fd to cd501a6 Compare April 2, 2020 02:14

Centril reviewed Apr 2, 2020

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nikomatsakis reviewed Apr 3, 2020

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src/librustc_trait_selection/traits/error_reporting/suggestions.rs Outdated Show resolved Hide resolved

nikomatsakis reviewed Apr 3, 2020

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rust-highfive assigned nikomatsakis and unassigned davidtwco Apr 8, 2020

nikomatsakis approved these changes Apr 10, 2020

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bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Apr 10, 2020

Dylan-DPC-zz mentioned this pull request Apr 10, 2020

Rollup of 5 pull requests #71012

Closed

Centril mentioned this pull request Apr 11, 2020

Rollup of 6 pull requests #71037

Closed

bors added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Apr 12, 2020

tmandry added 8 commits April 13, 2020 18:48

Use inner/outer generator naming instead of first/last

b129b32

I personally find this clearer.

Add test for rust-lang#68112 (existing output)

a40ec13

Improve span label

db0a5a1

Don't annotate type when type is opaque

7127ff3

Use "generator" instead of "future" when appropriate

6edfd66

Use clearer message when obligation is caused by await expr

aed7c30

Don't double-annotate the same Span

e340375

rustfmt

8ce334d

tmandry added 3 commits April 13, 2020 18:58

Include type info when available for awaited expr

df0a16b

Fix style nits

00795a9

Incorporate feedback into diagnostics

df64c5d

tmandry force-pushed the issue-68112 branch from 889cfe1 to df64c5d Compare April 14, 2020 01:58

Update test after rebase

4326d95

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Apr 14, 2020

bors added the merged-by-bors This PR was explicitly merged by bors. label Apr 14, 2020

bors merged commit a3ef360 into rust-lang:master Apr 14, 2020

tmandry deleted the issue-68112 branch April 14, 2020 23:43

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Improve async-await/generator obligation errors in some cases #70679

Improve async-await/generator obligation errors in some cases #70679

tmandry commented Apr 2, 2020 •

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Improve async-await/generator obligation errors in some cases #70679

Improve async-await/generator obligation errors in some cases #70679

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