Auto merge of #76580 - rokob:iss76011, r=estebank

Suggest async {} for async || {}

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.
This commit is contained in:
bors 2021-01-12 02:56:51 +00:00
commit 467f5e99a5
5 changed files with 34 additions and 17 deletions

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@ -14,6 +14,17 @@ use rustc_span::Span;
use tracing::debug;
macro_rules! gate_feature_fn {
($visitor: expr, $has_feature: expr, $span: expr, $name: expr, $explain: expr, $help: expr) => {{
let (visitor, has_feature, span, name, explain, help) =
(&*$visitor, $has_feature, $span, $name, $explain, $help);
let has_feature: bool = has_feature(visitor.features);
debug!("gate_feature(feature = {:?}, span = {:?}); has? {}", name, span, has_feature);
if !has_feature && !span.allows_unstable($name) {
feature_err_issue(&visitor.sess.parse_sess, name, span, GateIssue::Language, explain)
.help(help)
.emit();
}
}};
($visitor: expr, $has_feature: expr, $span: expr, $name: expr, $explain: expr) => {{
let (visitor, has_feature, span, name, explain) =
(&*$visitor, $has_feature, $span, $name, $explain);
@ -27,6 +38,9 @@ macro_rules! gate_feature_fn {
}
macro_rules! gate_feature_post {
($visitor: expr, $feature: ident, $span: expr, $explain: expr, $help: expr) => {
gate_feature_fn!($visitor, |x: &Features| x.$feature, $span, sym::$feature, $explain, $help)
};
($visitor: expr, $feature: ident, $span: expr, $explain: expr) => {
gate_feature_fn!($visitor, |x: &Features| x.$feature, $span, sym::$feature, $explain)
};
@ -597,6 +611,13 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session) {
let spans = sess.parse_sess.gated_spans.spans.borrow();
macro_rules! gate_all {
($gate:ident, $msg:literal, $help:literal) => {
if let Some(spans) = spans.get(&sym::$gate) {
for span in spans {
gate_feature_post!(&visitor, $gate, *span, $msg, $help);
}
}
};
($gate:ident, $msg:literal) => {
if let Some(spans) = spans.get(&sym::$gate) {
for span in spans {
@ -607,7 +628,11 @@ pub fn check_crate(krate: &ast::Crate, sess: &Session) {
}
gate_all!(if_let_guard, "`if let` guards are experimental");
gate_all!(let_chains, "`let` expressions in this position are experimental");
gate_all!(async_closure, "async closures are unstable");
gate_all!(
async_closure,
"async closures are unstable",
"to use an async block, remove the `||`: `async {`"
);
gate_all!(generators, "yield syntax is experimental");
gate_all!(or_patterns, "or-patterns syntax is experimental");
gate_all!(raw_ref_op, "raw address of syntax is experimental");

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@ -1599,10 +1599,6 @@ impl<'a> Parser<'a> {
} else {
Async::No
};
if let Async::Yes { span, .. } = asyncness {
// Feature-gate `async ||` closures.
self.sess.gated_spans.gate(sym::async_closure, span);
}
let capture_clause = self.parse_capture_clause()?;
let decl = self.parse_fn_block_decl()?;
@ -1619,6 +1615,11 @@ impl<'a> Parser<'a> {
}
};
if let Async::Yes { span, .. } = asyncness {
// Feature-gate `async ||` closures.
self.sess.gated_spans.gate(sym::async_closure, span);
}
Ok(self.mk_expr(
lo.to(body.span),
ExprKind::Closure(capture_clause, asyncness, movability, decl, body, lo.to(decl_hi)),

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@ -6,6 +6,7 @@ LL | let _ = async || {};
|
= note: see issue #62290 <https://github.com/rust-lang/rust/issues/62290> for more information
= help: add `#![feature(async_closure)]` to the crate attributes to enable
= help: to use an async block, remove the `||`: `async {`
error: aborting due to previous error

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@ -26,6 +26,6 @@ fn f4() {
}
fn f5() {
async //~ ERROR async closures are unstable
async
let x = 0; //~ ERROR expected one of `move`, `|`, or `||`, found keyword `let`
}

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@ -39,15 +39,5 @@ LL | async
LL | let x = 0;
| ^^^ unexpected token
error[E0658]: async closures are unstable
--> $DIR/block-no-opening-brace.rs:29:5
|
LL | async
| ^^^^^
|
= note: see issue #62290 <https://github.com/rust-lang/rust/issues/62290> for more information
= help: add `#![feature(async_closure)]` to the crate attributes to enable
error: aborting due to 5 previous errors
error: aborting due to 6 previous errors
For more information about this error, try `rustc --explain E0658`.