Auto merge of #123413 - petrochenkov:delegmulti2, r=fmease

delegation: Implement list delegation

```rust
reuse prefix::{a, b, c};
```

Using design described in https://github.com/rust-lang/rfcs/pull/3530#issuecomment-2020869823 (the lists are desugared at macro expansion time).
List delegations are expanded eagerly when encountered, similarly to `#[cfg]`s, and not enqueued for later resolution/expansion like regular macros or glob delegation (https://github.com/rust-lang/rust/pull/124135).

Part of https://github.com/rust-lang/rust/issues/118212.

1 files changed, 5 insertions, 2 deletions

diff --git a/compiler/rustc_parse/src/parser/path.rs b/compiler/rustc_parse/src/parser/path.rs
index c37d3f0441d..d845e8ab90d 100644
--- a/compiler/rustc_parse/src/parser/path.rs
+++ b/compiler/rustc_parse/src/parser/path.rs
@@ -95,12 +95,15 @@ impl<'a> Parser<'a> {
             debug!("parse_qpath: (decrement) count={:?}", self.unmatched_angle_bracket_count);
         }
 
-        if !self.recover_colon_before_qpath_proj() {
+        let is_import_coupler = self.is_import_coupler();
+        if !is_import_coupler && !self.recover_colon_before_qpath_proj() {
             self.expect(&token::PathSep)?;
         }
 
         let qself = P(QSelf { ty, path_span, position: path.segments.len() });
-        self.parse_path_segments(&mut path.segments, style, None)?;
+        if !is_import_coupler {
+            self.parse_path_segments(&mut path.segments, style, None)?;
+        }
 
         Ok((
             qself,