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Auto merge of #83722 - jyn514:stable-help, r=estebank

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On stable, suggest removing `#![feature]` for features that have been stabilized

I don't know how to test this (https://rust-lang.zulipchat.com/#narrow/stream/182449-t-compiler.2Fhelp/topic/Run.20tests.20without.20enabling.20nightly.20features.3F). I confirmed locally that this gives the
appropriate help with `channel = "beta"`:

```
error[E0554]: `#![feature]` may not be used on the beta release channel
 --> src/lib.rs:2:1
  |
2 | #![feature(min_const_generics)]
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove the attribute
  |
  = help: the feature `min_const_generics` has been stable since 1.51.0 and no longer requires an attribute to enable

error[E0554]: `#![feature]` may not be used on the beta release channel
 --> src/lib.rs:3:1
  |
3 | #![feature(min_const_generics, min_specialization)]
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = help: the feature `min_const_generics` has been stable since 1.51.0 and no longer requires an attribute to enable

error[E0554]: `#![feature]` may not be used on the beta release channel
 --> src/lib.rs:4:1
  |
4 | #![feature(box_patterns)]
  | ^^^^^^^^^^^^^^^^^^^^^^^^^
```

Closes https://github.com/rust-lang/rust/issues/83715.
This commit is contained in:
bors 2021-04-24 02:25:54 +00:00
commit a7aba58e96
1 changed files with 33 additions and 3 deletions
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36
compiler/rustc_ast_passes/src/feature_gate.rs
View File

@ -727,16 +727,46 @@ macro_rules! gate_all {
}
fn maybe_stage_features(sess: &Session, krate: &ast::Crate) {
use rustc_errors::Applicability;
if !sess.opts.unstable_features.is_nightly_build() {
let lang_features = &sess.features_untracked().declared_lang_features;
for attr in krate.attrs.iter().filter(|attr| sess.check_name(attr, sym::feature)) {
struct_span_err!(
let mut err = struct_span_err!(
sess.parse_sess.span_diagnostic,
attr.span,
E0554,
"`#![feature]` may not be used on the {} release channel",
option_env!("CFG_RELEASE_CHANNEL").unwrap_or("(unknown)")
)
.emit();
);
let mut all_stable = true;
for ident in
attr.meta_item_list().into_iter().flatten().map(|nested| nested.ident()).flatten()
{
let name = ident.name;
let stable_since = lang_features
.iter()
.flat_map(|&(feature, _, since)| if feature == name { since } else { None })
.next();
if let Some(since) = stable_since {
err.help(&format!(
"the feature `{}` has been stable since {} and no longer requires \
an attribute to enable",
name, since
));
} else {
all_stable = false;
}
}
if all_stable {
err.span_suggestion(
attr.span,
"remove the attribute",
String::new(),
Applicability::MachineApplicable,
);
}
err.emit();
}
}
}