diff options
| -rw-r--r-- | compiler/rustc_typeck/src/check/op.rs | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/compiler/rustc_typeck/src/check/op.rs b/compiler/rustc_typeck/src/check/op.rs index d4bb3d43eff..322b8f1e749 100644 --- a/compiler/rustc_typeck/src/check/op.rs +++ b/compiler/rustc_typeck/src/check/op.rs @@ -631,18 +631,19 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { let rm_borrow_msg = "remove the borrow to obtain an owned `String`"; let to_owned_msg = "create an owned `String` from a string reference"; - let string_type = self.tcx.get_diagnostic_item(sym::String); - let is_std_string = |ty: Ty<'tcx>| match ty.ty_adt_def() { - Some(ty_def) => Some(ty_def.did()) == string_type, - None => false, + let is_std_string = |ty: Ty<'tcx>| { + ty.ty_adt_def() + .map_or(false, |ty_def| self.tcx.is_diagnostic_item(sym::String, ty_def.did())) }; match (lhs_ty.kind(), rhs_ty.kind()) { (&Ref(_, l_ty, _), &Ref(_, r_ty, _)) // &str or &String + &str, &String or &&str - if (*l_ty.kind() == Str || is_std_string(l_ty)) && ( - *r_ty.kind() == Str || is_std_string(r_ty) || - &format!("{:?}", rhs_ty) == "&&str" - ) => + if (*l_ty.kind() == Str || is_std_string(l_ty)) + && (*r_ty.kind() == Str + || is_std_string(r_ty) + || matches!( + r_ty.kind(), Ref(_, inner_ty, _) if *inner_ty.kind() == Str + )) => { if let IsAssign::No = is_assign { // Do not supply this message if `&str += &str` err.span_label(op.span, "`+` cannot be used to concatenate two `&str` strings"); |