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Auto merge of #90986 - camsteffen:nested-filter, r=cjgillot

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Replace `NestedVisitorMap` with generic `NestedFilter`

This is an attempt to make the `intravisit::Visitor` API simpler and "more const" with regard to nested visiting.

With this change, `intravisit::Visitor` does not visit nested things by default, unless you specify `type NestedFilter = nested_filter::OnlyBodies` (or `All`). `nested_visit_map` returns `Self::Map` instead of `NestedVisitorMap<Self::Map>`. It panics by default (unreachable if `type NestedFilter` is omitted).

One somewhat trixty thing here is that `nested_filter::{OnlyBodies, All}` live in `rustc_middle` so that they may have `type Map = map::Map` and so that `impl Visitor`s never need to specify `type Map` - it has a default of `Self::NestedFilter::Map`.
This commit is contained in:
bors 2022-01-17 14:50:50 +00:00
commit ee5d8d37ba
110 changed files with 388 additions and 947 deletions
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8
compiler/rustc_ast_lowering/src/index.rs
View file

@ -3,7 +3,7 @@ use rustc_data_structures::sorted_map::SortedMap;
use rustc_hir as hir;
use rustc_hir::def_id::LocalDefId;
use rustc_hir::definitions;
use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
use rustc_hir::intravisit::{self, Visitor};
use rustc_hir::*;
use rustc_index::vec::{Idx, IndexVec};
use rustc_session::Session;
@ -101,16 +101,10 @@ impl<'a, 'hir> NodeCollector<'a, 'hir> {
}
impl<'a, 'hir> Visitor<'hir> for NodeCollector<'a, 'hir> {
type Map = !;
/// Because we want to track parent items and so forth, enable
/// deep walking so that we walk nested items in the context of
/// their outer items.
fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
panic!("`visit_nested_xxx` must be manually implemented in this visitor");
}
fn visit_nested_item(&mut self, item: ItemId) {
debug!("visit_nested_item: {:?}", item);
self.insert_nested(item.def_id);

6
compiler/rustc_ast_lowering/src/lib.rs
View file

@ -2436,12 +2436,6 @@ fn lifetimes_from_impl_trait_bounds(
}
impl<'r, 'v> intravisit::Visitor<'v> for ImplTraitLifetimeCollector<'r> {
type Map = intravisit::ErasedMap<'v>;
fn nested_visit_map(&mut self) -> intravisit::NestedVisitorMap<Self::Map> {
intravisit::NestedVisitorMap::None
}
fn visit_generic_args(&mut self, span: Span, parameters: &'v hir::GenericArgs<'v>) {
// Don't collect elided lifetimes used inside of `Fn()` syntax.
if parameters.parenthesized {