);
let mut sugg = None;
let mut sugg_mutref = false;
- if let ty::Ref(reg, _, mutbl) = *self.cast_ty.kind() {
+ if let ty::Ref(reg, cast_ty, mutbl) = *self.cast_ty.kind() {
if let ty::RawPtr(TypeAndMut { ty: expr_ty, .. }) = *self.expr_ty.kind() {
if fcx
.try_coerce(
)
.is_ok()
{
- sugg = Some(format!("&{}*", mutbl.prefix_str()));
+ sugg = Some((format!("&{}*", mutbl.prefix_str()), cast_ty == expr_ty));
}
} else if let ty::Ref(expr_reg, expr_ty, expr_mutbl) = *self.expr_ty.kind() {
if expr_mutbl == Mutability::Not
)
.is_ok()
{
- sugg = Some(format!("&{}", mutbl.prefix_str()));
+ sugg = Some((format!("&{}", mutbl.prefix_str()), false));
}
} else if let ty::RawPtr(TypeAndMut { mutbl, .. }) = *self.cast_ty.kind() {
if fcx
)
.is_ok()
{
- sugg = Some(format!("&{}", mutbl.prefix_str()));
+ sugg = Some((format!("&{}", mutbl.prefix_str()), false));
}
}
if sugg_mutref {
err.span_label(self.span, "invalid cast");
err.span_note(self.expr.span, "this reference is immutable");
err.span_note(self.cast_span, "trying to cast to a mutable reference type");
- } else if let Some(sugg) = sugg {
+ } else if let Some((sugg, remove_cast)) = sugg {
err.span_label(self.span, "invalid cast");
- err.span_suggestion_verbose(
- self.expr.span.shrink_to_lo(),
+
+ let has_parens = fcx
+ .tcx
+ .sess
+ .source_map()
+ .span_to_snippet(self.expr.span)
+ .map_or(false, |snip| snip.starts_with("("));
+
+ // Very crude check to see whether the expression must be wrapped
+ // in parentheses for the suggestion to work (issue #89497).
+ // Can/should be extended in the future.
+ let needs_parens = !has_parens
+ && match self.expr.kind {
+ hir::ExprKind::Cast(..) => true,
+ _ => false,
+ };
+
+ let mut suggestion = vec![(self.expr.span.shrink_to_lo(), sugg)];
+ if needs_parens {
+ suggestion[0].1 += "(";
+ suggestion.push((self.expr.span.shrink_to_hi(), ")".to_string()));
+ }
+ if remove_cast {
+ suggestion.push((
+ self.expr.span.shrink_to_hi().to(self.cast_span),
+ String::new(),
+ ));
+ }
+
+ err.multipart_suggestion_verbose(
"consider borrowing the value",
- sugg,
+ suggestion,
Applicability::MachineApplicable,
);
} else if !matches!(