bjoernager/rust
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Fix rebase and add comments

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This commit is contained in:
Esteban Küber 2020-09-11 17:20:56 -07:00
parent dc53cfea7e
commit c6f2ddf1cb
1 changed files with 6 additions and 1 deletions
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7
compiler/rustc_typeck/src/check/_match.rs
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@ -6,7 +6,7 @@ use rustc_infer::traits::Obligation;
use rustc_middle::ty::{self, ToPredicate, Ty}; use rustc_middle::ty::{self, ToPredicate, Ty};
use rustc_span::Span; use rustc_span::Span;
use rustc_trait_selection::opaque_types::InferCtxtExt as _; use rustc_trait_selection::opaque_types::InferCtxtExt as _;
use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _; use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
use rustc_trait_selection::traits::{ use rustc_trait_selection::traits::{
IfExpressionCause, MatchExpressionArmCause, ObligationCause, ObligationCauseCode, IfExpressionCause, MatchExpressionArmCause, ObligationCause, ObligationCauseCode,
}; };
@ -153,12 +153,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
); );
suggest_box &= self.infcx.predicate_must_hold_modulo_regions(&obl); suggest_box &= self.infcx.predicate_must_hold_modulo_regions(&obl);
if !suggest_box { if !suggest_box {
// We've encountered some obligation that didn't hold, so the
// return expression can't just be boxed. We don't need to
// evaluate the rest of the obligations.
break; break;
} }
} }
_ => {} _ => {}
} }
} }
// If all the obligations hold (or there are no obligations) the tail expression
// we can suggest to return a boxed trait object instead of an opaque type.
if suggest_box { self.ret_type_span.clone() } else { None } if suggest_box { self.ret_type_span.clone() } else { None }
} }
_ => None, _ => None,