Fix removed `box_syntax` diagnostic if source isn't available

1 files changed, 6 insertions, 4 deletions

diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs
index a4d9d97045d..1b053c39e64 100644
--- a/compiler/rustc_parse/src/parser/expr.rs
+++ b/compiler/rustc_parse/src/parser/expr.rs
@@ -618,10 +618,12 @@ impl<'a> Parser<'a> {
     /// Parse `box expr` - this syntax has been removed, but we still parse this
     /// for now to provide a more useful error
     fn parse_expr_box(&mut self, box_kw: Span) -> PResult<'a, (Span, ExprKind)> {
-        let (span, _) = self.parse_expr_prefix_common(box_kw)?;
-        let inner_span = span.with_lo(box_kw.hi());
-        let code = self.psess.source_map().span_to_snippet(inner_span).unwrap();
-        let guar = self.dcx().emit_err(errors::BoxSyntaxRemoved { span: span, code: code.trim() });
+        let (span, expr) = self.parse_expr_prefix_common(box_kw)?;
+        // Make a multipart suggestion instead of `span_to_snippet` in case source isn't available
+        let box_kw_and_lo = box_kw.until(self.interpolated_or_expr_span(&expr));
+        let hi = span.shrink_to_hi();
+        let sugg = errors::AddBoxNew { box_kw_and_lo, hi };
+        let guar = self.dcx().emit_err(errors::BoxSyntaxRemoved { span, sugg });
         Ok((span, ExprKind::Err(guar)))
     }