nordic-dev.net/rust
nordic-dev.net/rust
2
0
Fork 0
mirror of https://github.com/rust-lang/rust.git synced 2024-10-30 22:12:15 +00:00
Code Issues Packages Projects Releases Wiki Activity

Add comments about lifetime collect and create lifetime defs for RPITs

Browse Source
This commit is contained in:
Santiago Pastorino 2022-08-03 17:06:30 -03:00
parent 40bcbed3c7
commit 78585098b5
No known key found for this signature in database
GPG Key ID: 8131A24E0C79EFAF
1 changed files with 8 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
compiler/rustc_ast_lowering/src/lib.rs
View File

@ -1345,10 +1345,16 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
self.with_hir_id_owner(opaque_ty_node_id, |lctx| {
if origin != hir::OpaqueTyOrigin::TyAlias {
// When lowering `fn foo<'a>() -> impl Debug + 'a`, the `lifetime_collector` finds
// the set of lifetimes that appear in the bounds (in this case, 'a) and returns
// that set in the variable lifetimes_in_bounds.
let lifetimes_in_bounds =
lifetime_collector::lifetimes_in_bounds(&lctx.resolver, bounds);
debug!(?lifetimes_in_bounds);
// For each captured lifetime (e.g., 'a), we create a new lifetime parameter that
// is a generic defined on the TAIT, so we have type Foo<'a1> = ... and we
// establish a mapping from the original parameter 'a to the new parameter 'a1.
collected_lifetimes = lctx.create_lifetime_defs(
opaque_ty_def_id,
&lifetimes_in_bounds,
@ -1359,6 +1365,8 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
debug!(?collected_lifetimes);
lctx.with_remapping(new_remapping, |lctx| {
// Then when we lower the param bounds, references to 'a are remapped to 'a1, so we
// get back Debug + 'a1, which is suitable for use on the TAIT.
let hir_bounds = lctx.lower_param_bounds(bounds, itctx);
let lifetime_defs = lctx.arena.alloc_from_iter(collected_lifetimes.iter().map(