Github Suggest async {} for async || {} by rokob · Pull Request #76580 · rust-la...
source link: https://github.com/rust-lang/rust/pull/76580
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Suggest async {} for async || {} #76580
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rokob commented on Sep 11, 2020
Fixes #76011
This adds support for adding help diagnostics to the feature gating checks and
then uses it for the async_closure gate to add the extra bit of help
information as described in the issue.
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rust-highfive commented on Sep 11, 2020
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Can we add a test? It should live somewhere in src/test/ui/** and after the .rs file is created (and test check comments are added in the right place) you can run ./x.py test src/test/ui --stage 1 --bless to autogenerate the .stderr files.
debug!("gate_feature(feature = {:?}, span = {:?}); has? {}", name, span, has_feature);
if !has_feature && !span.allows_unstable($name) {
feature_err_issue(&visitor.sess.parse_sess, name, span, GateIssue::Language, explain)
.span_help(span, help)
estebank on Sep 12, 2020
Contributor
Because we have a single span, I think this should be a bare help call (without a span) so the output isn't too verbose/redundant. I would not close #76011, as that is asking for a structured suggestion, which we might be able to provide in the future (but this current change is a great mitigation).
Contributor
Author
rokob commented on Sep 23, 2020
I updated the src/test/ui/async-await/feature-async-closure UI test. I also made a change to compiler/rustc_parse/src/parser/expr.rs because otherwise this help would show up in this test src/test/ui/parser/block-no-opening-brace.
I can backout that change if you want and instead have this help show up in that case as well. But looking at that example, it didn't seem right to me that this code:
fn f5() {
async
let x = 0;
}
would produce an error about async closures being unstable. You don't know that this is trying to be a closure, it could very well have been an async block which is not unstable. The help message I am adding makes this part even more confusing because it suggests removing the || and replacing it with a { but there is no ||. I think moving the feature gate until after the parsing of the rest of the closure has no semantic impact but makes more sense as you shouldn't assume you have a closure if you don't have |, or ||, or {.
Member
jyn514 commented on Nov 20, 2020
ping @estebank - is there a better reviewer for this?
Member
camelid commented 21 days ago
I think estebank is catching up on reviews now.
@bors r+
Noticed the following output
error: expected one of `move`, `|`, or `||`, found keyword `let`
--> $DIR/block-no-opening-brace.rs:30:9
|
LL | async
| - expected one of `move`, `|`, or `||`
LL | let x = 0;
| ^^^ unexpected token
should also include { as an expected token, but that's independent of this. Edit: Created #80931.
Contributor
bors commented 19 days ago
Commit 5b475a4 has been approved by estebank
Contributor
bors commented 19 days ago
Testing commit Contributor
bors commented 19 days ago
Test successful - checks-actions
Approved by: estebank
Pushing 467f5e9 to master...
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