Auto merge of #128461 - matthiaskrgr:rollup-3dpp11g, r=matthiaskrgr

Rollup of 7 pull requests

Successful merges:

 - #123813 (Add `REDUNDANT_IMPORTS` lint for new redundant import detection)
 - #126697 ([RFC] mbe: consider the `_` in 2024 an expression)
 - #127159 (match lowering: Hide `Candidate` from outside the lowering algorithm)
 - #128244 (Peel off explicit (or implicit) deref before suggesting clone on move error in borrowck, remove some hacks)
 - #128431 (Add myself as VxWorks target maintainer for reference)
 - #128438 (Add special-case for [T, 0] in dropck_outlives)
 - #128457 (Fix docs for OnceLock::get_mut_or_init)

r? `@ghost`
`@rustbot` modify labels: rollup

1 files changed, 10 insertions, 1 deletions

diff --git a/compiler/rustc_parse/src/parser/nonterminal.rs b/compiler/rustc_parse/src/parser/nonterminal.rs
index bd9d96ba573..999f6f0eeb0 100644
--- a/compiler/rustc_parse/src/parser/nonterminal.rs
+++ b/compiler/rustc_parse/src/parser/nonterminal.rs
@@ -39,6 +39,7 @@ impl<'a> Parser<'a> {
         }
 
         match kind {
+            // `expr_2021` and earlier
             NonterminalKind::Expr(Expr2021 { .. }) => {
                 token.can_begin_expr()
                 // This exception is here for backwards compatibility.
@@ -46,8 +47,16 @@ impl<'a> Parser<'a> {
                 // This exception is here for backwards compatibility.
                 && !token.is_keyword(kw::Const)
             }
+            // Current edition expressions
             NonterminalKind::Expr(Expr) => {
-                token.can_begin_expr()
+                // In Edition 2024, `_` is considered an expression, so we
+                // need to allow it here because `token.can_begin_expr()` does
+                // not consider `_` to be an expression.
+                //
+                // Because `can_begin_expr` is used elsewhere, we need to reduce
+                // the scope of where the `_` is considered an expression to
+                // just macro parsing code.
+                (token.can_begin_expr() || token.is_keyword(kw::Underscore))
                 // This exception is here for backwards compatibility.
                 && !token.is_keyword(kw::Let)
             }