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Trying to suggest additional lifetime parameter #102323

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Merged
merged 6 commits into from
Oct 10, 2022
Merged

Trying to suggest additional lifetime parameter #102323

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887515a
Trying to suggest additional lifetime parameter
Stoozy Sep 26, 2022
365457b
Using multipart suggestion
Stoozy Sep 27, 2022
24c8e27
Properly formatting the multipart suggestion
Stoozy Sep 27, 2022
e7cb6ad
Proper span for new generic param suggestion
Stoozy Sep 28, 2022
ef930a2
Emitting error regardless of new param suggestion
Stoozy Sep 29, 2022
2657f9d
Removed unnecessary for loop
Stoozy Oct 1, 2022
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40 changes: 32 additions & 8 deletions compiler/rustc_resolve/src/late/lifetimes.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,7 @@

use rustc_ast::walk_list;
use rustc_data_structures::fx::{FxHashSet, FxIndexMap, FxIndexSet};
use rustc_errors::struct_span_err;
use rustc_errors::{struct_span_err};
use rustc_hir as hir;
use rustc_hir::def::{DefKind, Res};
use rustc_hir::def_id::LocalDefId;
Expand All @@ -24,6 +24,7 @@ use rustc_span::symbol::{sym, Ident};
use rustc_span::Span;
use std::fmt;


trait RegionExt {
fn early(hir_map: Map<'_>, param: &GenericParam<'_>) -> (LocalDefId, Region);

Expand Down Expand Up @@ -1318,13 +1319,36 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
&& let hir::IsAsync::NotAsync = self.tcx.asyncness(lifetime_ref.hir_id.owner.def_id)
&& !self.tcx.features().anonymous_lifetime_in_impl_trait
{
rustc_session::parse::feature_err(
&self.tcx.sess.parse_sess,
sym::anonymous_lifetime_in_impl_trait,
lifetime_ref.span,
"anonymous lifetimes in `impl Trait` are unstable",
).emit();
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You can keep this a feature error. You can keep this line, but instead of calling emit immediately, store it in a mut variable diag, decorate it using span_... methods, and call emit when you're done.

return;

match self.tcx.hir().get_generics(lifetime_ref.hir_id.owner.to_def_id().as_local().unwrap()) {
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Suggested change
match self.tcx.hir().get_generics(lifetime_ref.hir_id.owner.to_def_id().as_local().unwrap()) {
match self.tcx.hir().get_generics(lifetime_ref.hir_id.owner.def_id) {

Some(generics) => {
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Now you have generics you want 2 things to know where to suggest the lifetime parameter param_span, and in what form param_sugg.
Once you have that, you call

diag.multipart_suggestion(
  "consider introducing a named lifetime parameter",
  vec![
    (lifetime_ref.span, "'a".to_owned()), // this is at the use site
    (param_span, param_sugg), // this is in generics
  ],
)

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it seems if I put "'a" for the message, it replaces the ampersand symbol from the original posters input. Should I keep this?

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You can use lifetime_ref.span.shrink_to_hi() instead then.

for i in 0..generics.params.len() {
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You only use a single parameter. Could you separate the choice of param from the suggestion / move the suggestion code out of the loop?


if !generics.span.contains(generics.params[i].span) {
struct_span_err!(
self.tcx.sess,
lifetime_ref.span,
E0106,
"missing lifetime specifier"
)
.span_label(lifetime_ref.span, "expected named lifetime parameter")
.span_help(generics.span, "consider introducing a named lifetime parameter")
.emit();
return;
}
}
},
None => {
rustc_session::parse::feature_err(
&self.tcx.sess.parse_sess,
sym::anonymous_lifetime_in_impl_trait,
lifetime_ref.span,
"anonymous lifetimes in `impl Trait` are unstable",
).emit();
return;
}
}

}
scope = s;
}
Expand Down