Add ast::ExprKind::Dummy

compiler/rustc_ast_lowering/src/expr.rs

@@ -14,6 +14,7 @@ use rustc_ast::*;
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
+use rustc_middle::span_bug;
 use rustc_session::errors::report_lit_error;
 use rustc_span::source_map::{respan, Spanned};
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
@@ -331,6 +332,11 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 ExprKind::Err => {
                     hir::ExprKind::Err(self.dcx().span_delayed_bug(e.span, "lowered ExprKind::Err"))
                 }
+
+                ExprKind::Dummy => {
+                    span_bug!(e.span, "lowered ExprKind::Dummy")
+                }
+
                 ExprKind::Try(sub_expr) => self.lower_expr_try(e.span, sub_expr),
 
                 ExprKind::Paren(_) | ExprKind::ForLoop { .. } => {