diff options
| -rw-r--r-- | compiler/rustc_trait_selection/src/traits/coherence.rs | 43 |
1 files changed, 25 insertions, 18 deletions
diff --git a/compiler/rustc_trait_selection/src/traits/coherence.rs b/compiler/rustc_trait_selection/src/traits/coherence.rs index 80ed9023d96..ab1dc8fcbfe 100644 --- a/compiler/rustc_trait_selection/src/traits/coherence.rs +++ b/compiler/rustc_trait_selection/src/traits/coherence.rs @@ -13,6 +13,7 @@ use crate::traits::{ self, FulfillmentContext, Normalized, Obligation, ObligationCause, PredicateObligation, PredicateObligations, SelectionContext, }; +use rustc_ast::Attribute; use rustc_hir::def_id::{DefId, LOCAL_CRATE}; use rustc_middle::ty::fast_reject::{self, SimplifyParams, StripReferences}; use rustc_middle::ty::fold::TypeFoldable; @@ -160,24 +161,30 @@ impl OverlapMode { } fn overlap_mode<'tcx>(tcx: TyCtxt<'tcx>, impl1_def_id: DefId, impl2_def_id: DefId) -> OverlapMode { - if tcx.has_attr(impl1_def_id, sym::rustc_strict_coherence) - != tcx.has_attr(impl2_def_id, sym::rustc_strict_coherence) - { - bug!("Use strict coherence on both impls",); - } - - if tcx.has_attr(impl1_def_id, sym::rustc_with_negative_coherence) - != tcx.has_attr(impl2_def_id, sym::rustc_with_negative_coherence) - { - bug!("Use with negative coherence on both impls",); - } - - if tcx.has_attr(impl1_def_id, sym::rustc_strict_coherence) { - OverlapMode::Strict - } else if tcx.has_attr(impl1_def_id, sym::rustc_with_negative_coherence) { - OverlapMode::WithNegative - } else { - OverlapMode::Stable + // Find the possible coherence mode override opt-in attributes for each `DefId` + let find_coherence_attr = |attr: &Attribute| { + let name = attr.name_or_empty(); + match name { + sym::rustc_with_negative_coherence | sym::rustc_strict_coherence => Some(name), + _ => None, + } + }; + let impl1_coherence_mode = tcx.get_attrs(impl1_def_id).iter().find_map(find_coherence_attr); + let impl2_coherence_mode = tcx.get_attrs(impl2_def_id).iter().find_map(find_coherence_attr); + + // If there are any (that currently happens in tests), they need to match. Otherwise, the + // default 1.0 rules are used. + match (impl1_coherence_mode, impl2_coherence_mode) { + (None, None) => OverlapMode::Stable, + (Some(sym::rustc_with_negative_coherence), Some(sym::rustc_with_negative_coherence)) => { + OverlapMode::WithNegative + } + (Some(sym::rustc_strict_coherence), Some(sym::rustc_strict_coherence)) => { + OverlapMode::Strict + } + (Some(mode), _) | (_, Some(mode)) => { + bug!("Use the same coherence mode on both impls: {}", mode) + } } } |