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Auto merge of #98279 - cjgillot:all-fresh-nofn, r=petrochenkov

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Create elided lifetime parameters for function-like types

Split from https://github.com/rust-lang/rust/pull/97720

This PR refactor lifetime generic parameters in bare function types and parenthesized traits to introduce the additional required lifetimes as fresh parameters in a `for<>` bound.

This PR does the same to lifetimes appearing in closure signatures, and as-if introducing `for<>` bounds on closures (without the associated change in semantics).

r? `@petrochenkov`
This commit is contained in:
bors 2022-06-22 10:48:58 +00:00
commit 10f4ce324b
28 changed files with 816 additions and 607 deletions
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6
compiler/rustc_typeck/src/astconv/mod.rs
View file

@ -2920,13 +2920,15 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
) {
for br in referenced_regions.difference(&constrained_regions) {
let br_name = match *br {
ty::BrNamed(_, kw::UnderscoreLifetime) | ty::BrAnon(_) | ty::BrEnv => {
"an anonymous lifetime".to_string()
}
ty::BrNamed(_, name) => format!("lifetime `{}`", name),
ty::BrAnon(_) | ty::BrEnv => "an anonymous lifetime".to_string(),
};
let mut err = generate_err(&br_name);
if let ty::BrAnon(_) = *br {
if let ty::BrNamed(_, kw::UnderscoreLifetime) | ty::BrAnon(_) = *br {
// The only way for an anonymous lifetime to wind up
// in the return type but **also** be unconstrained is
// if it only appears in "associated types" in the

66
compiler/rustc_typeck/src/check/compare_method.rs
View file

@ -628,24 +628,40 @@ fn compare_number_of_generics<'tcx>(
let mut err_occurred = None;
for (kind, trait_count, impl_count) in matchings {
if impl_count != trait_count {
let arg_spans = |kind: ty::AssocKind, generics: &hir::Generics<'_>| {
let mut spans = generics
.params
.iter()
.filter(|p| match p.kind {
hir::GenericParamKind::Lifetime {
kind: hir::LifetimeParamKind::Elided,
} => {
// A fn can have an arbitrary number of extra elided lifetimes for the
// same signature.
!matches!(kind, ty::AssocKind::Fn)
}
_ => true,
})
.map(|p| p.span)
.collect::<Vec<Span>>();
if spans.is_empty() {
spans = vec![generics.span]
}
spans
};
let (trait_spans, impl_trait_spans) = if let Some(def_id) = trait_.def_id.as_local() {
let trait_item = tcx.hir().expect_trait_item(def_id);
if trait_item.generics.params.is_empty() {
(Some(vec![trait_item.generics.span]), vec![])
} else {
let arg_spans: Vec<Span> =
trait_item.generics.params.iter().map(|p| p.span).collect();
let impl_trait_spans: Vec<Span> = trait_item
.generics
.params
.iter()
.filter_map(|p| match p.kind {
GenericParamKind::Type { synthetic: true, .. } => Some(p.span),
_ => None,
})
.collect();
(Some(arg_spans), impl_trait_spans)
}
let arg_spans: Vec<Span> = arg_spans(trait_.kind, trait_item.generics);
let impl_trait_spans: Vec<Span> = trait_item
.generics
.params
.iter()
.filter_map(|p| match p.kind {
GenericParamKind::Type { synthetic: true, .. } => Some(p.span),
_ => None,
})
.collect();
(Some(arg_spans), impl_trait_spans)
} else {
(trait_span.map(|s| vec![s]), vec![])
};
@ -660,23 +676,7 @@ fn compare_number_of_generics<'tcx>(
_ => None,
})
.collect();
let spans = if impl_item.generics.params.is_empty() {
vec![impl_item.generics.span]
} else {
impl_item
.generics
.params
.iter()
.filter(|p| {
matches!(
p.kind,
hir::GenericParamKind::Type { .. }
| hir::GenericParamKind::Const { .. }
)
})
.map(|p| p.span)
.collect::<Vec<Span>>()
};
let spans = arg_spans(impl_.kind, impl_item.generics);
let span = spans.first().copied();
let mut err = tcx.sess.struct_span_err_with_code(