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Simplify collect_in_band_defs.

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This commit is contained in:
Camille GILLOT 2021-11-12 14:45:19 +01:00
parent 0b6f079e49
commit 6e7ec0c5b4
1 changed files with 35 additions and 36 deletions
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71
compiler/rustc_ast_lowering/src/lib.rs
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@ -646,31 +646,18 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
/// parameter while `f` is running (and restored afterwards).
fn collect_in_band_defs<T>(
&mut self,
parent_def_id: LocalDefId,
anonymous_lifetime_mode: AnonymousLifetimeMode,
f: impl FnOnce(&mut Self) -> (Vec<hir::GenericParam<'hir>>, T),
) -> (Vec<hir::GenericParam<'hir>>, T) {
f: impl FnOnce(&mut Self) -> T,
) -> (Vec<(Span, ParamName)>, T) {
assert!(!self.is_collecting_in_band_lifetimes);
assert!(self.lifetimes_to_define.is_empty());
let old_anonymous_lifetime_mode = self.anonymous_lifetime_mode;
self.anonymous_lifetime_mode = anonymous_lifetime_mode;
self.is_collecting_in_band_lifetimes = true;
let (in_band_ty_params, res) = f(self);
let res = f(self);
self.is_collecting_in_band_lifetimes = false;
self.anonymous_lifetime_mode = old_anonymous_lifetime_mode;
let lifetimes_to_define = self.lifetimes_to_define.split_off(0);
let params = lifetimes_to_define
.into_iter()
.map(|(span, hir_name)| self.lifetime_to_generic_param(span, hir_name, parent_def_id))
.chain(in_band_ty_params.into_iter())
.collect();
(params, res)
let lifetimes_to_define = std::mem::take(&mut self.lifetimes_to_define);
(lifetimes_to_define, res)
}
/// Converts a lifetime into a new generic parameter.
@ -785,27 +772,39 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
anonymous_lifetime_mode: AnonymousLifetimeMode,
f: impl FnOnce(&mut Self, &mut Vec<hir::GenericParam<'hir>>) -> T,
) -> (hir::Generics<'hir>, T) {
let (in_band_defs, (mut lowered_generics, res)) =
self.with_in_scope_lifetime_defs(&generics.params, |this| {
this.collect_in_band_defs(parent_def_id, anonymous_lifetime_mode, |this| {
let mut params = Vec::new();
// Note: it is necessary to lower generics *before* calling `f`.
// When lowering `async fn`, there's a final step when lowering
// the return type that assumes that all in-scope lifetimes have
// already been added to either `in_scope_lifetimes` or
// `lifetimes_to_define`. If we swapped the order of these two,
// in-band-lifetimes introduced by generics or where-clauses
// wouldn't have been added yet.
let generics = this.lower_generics_mut(
generics,
ImplTraitContext::Universal(&mut params, this.current_hir_id_owner),
);
let res = f(this, &mut params);
(params, (generics, res))
let (lifetimes_to_define, (mut lowered_generics, impl_trait_defs, res)) = self
.collect_in_band_defs(|this| {
this.with_anonymous_lifetime_mode(anonymous_lifetime_mode, |this| {
this.with_in_scope_lifetime_defs(&generics.params, |this| {
let mut impl_trait_defs = Vec::new();
// Note: it is necessary to lower generics *before* calling `f`.
// When lowering `async fn`, there's a final step when lowering
// the return type that assumes that all in-scope lifetimes have
// already been added to either `in_scope_lifetimes` or
// `lifetimes_to_define`. If we swapped the order of these two,
// in-band-lifetimes introduced by generics or where-clauses
// wouldn't have been added yet.
let generics = this.lower_generics_mut(
generics,
ImplTraitContext::Universal(
&mut impl_trait_defs,
this.current_hir_id_owner,
),
);
let res = f(this, &mut impl_trait_defs);
(generics, impl_trait_defs, res)
})
})
});
lowered_generics.params.extend(in_band_defs);
lowered_generics.params.extend(
lifetimes_to_define
.into_iter()
.map(|(span, hir_name)| {
self.lifetime_to_generic_param(span, hir_name, parent_def_id)
})
.chain(impl_trait_defs),
);
let lowered_generics = lowered_generics.into_generics(self.arena);
(lowered_generics, res)