Fix an ICE on an invalid binding @ ... in a tuple struct pattern

src/librustc_resolve/late.rs

@@ -1500,11 +1500,17 @@ impl<'a, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
  pat_src: PatternSource,
  bindings: &mut SmallVec<[(PatBoundCtx, FxHashSet<Ident>); 1]>,
  ) {
+ let is_tuple_struct_pat = matches!(pat.kind, PatKind::TupleStruct(_, _));
+
  // Visit all direct subpatterns of this pattern.
  pat.walk(&mut |pat| {
  debug!("resolve_pattern pat={:?} node={:?}", pat, pat.kind);
  match pat.kind {
- PatKind::Ident(bmode, ident, ref sub) => {
+ // In tuple struct patterns ignore the invalid `ident @ ...`.
+ // It will be handled as an error by the AST lowering.
+ PatKind::Ident(bmode, ident, ref sub)
+ if !(is_tuple_struct_pat && sub.as_ref().filter(|p| p.is_rest()).is_some()) =>
+ {
  // First try to resolve the identifier as some existing entity,
  // then fall back to a fresh binding.
  let has_sub = sub.is_some();

src/test/ui/issues/issue-74539.rs

@@ -0,0 +1,12 @@
+enum E {
+ A(u8, u8),
+}
+
+fn main() {
+ let e = E::A(2, 3);
+ match e {
+ E::A(x @ ..) => { //~ ERROR `x @` is not allowed in a tuple
+ x //~ ERROR cannot find value `x` in this scope
+ }
+ };
+}

src/test/ui/issues/issue-74539.stderr

@@ -0,0 +1,21 @@
+error[E0425]: cannot find value `x` in this scope
+ --> $DIR/issue-74539.rs:9:13
+ |
+LL | x
+ | ^ help: a local variable with a similar name exists: `e`
+
+error: `x @` is not allowed in a tuple struct
+ --> $DIR/issue-74539.rs:8:14
+ |
+LL | E::A(x @ ..) => {
+ | ^^^^^^ this is only allowed in slice patterns
+ |
+ = help: remove this and bind each tuple field independently
+help: if you don't need to use the contents of x, discard the tuple's remaining fields
+ |
+LL | E::A(..) => {
+ | ^^
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0425`.