delay_span_bug instead of silent ignore

Author: Mark-Simulacrum

src/librustc_resolve/late.rs

@@ -1415,16 +1415,22 @@ impl<'a, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
             match pat.kind {
                 // 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();
-                    let res = self
-                        .try_resolve_as_non_binding(pat_src, pat, bmode, ident, has_sub)
-                        .unwrap_or_else(|| self.fresh_binding(ident, pat.id, pat_src, bindings));
-                    self.r.record_partial_res(pat.id, PartialRes::new(res));
+                PatKind::Ident(bmode, ident, ref sub) => {
+                    if is_tuple_struct_pat && sub.as_ref().filter(|p| p.is_rest()).is_some() {
+                        self.r
+                            .session
+                            .delay_span_bug(ident.span, "ident in tuple pattern is invalid");
+                    } else {
+                        // First try to resolve the identifier as some existing entity,
+                        // then fall back to a fresh binding.
+                        let has_sub = sub.is_some();
+                        let res = self
+                            .try_resolve_as_non_binding(pat_src, pat, bmode, ident, has_sub)
+                            .unwrap_or_else(|| {
+                                self.fresh_binding(ident, pat.id, pat_src, bindings)
+                            });
+                        self.r.record_partial_res(pat.id, PartialRes::new(res));
+                    }
                 }
                 PatKind::TupleStruct(ref path, ..) => {
                     self.smart_resolve_path(pat.id, None, path, PathSource::TupleStruct);