diff options
| -rw-r--r-- | src/librustc_typeck/check/wfcheck.rs | 37 |
1 files changed, 35 insertions, 2 deletions
diff --git a/src/librustc_typeck/check/wfcheck.rs b/src/librustc_typeck/check/wfcheck.rs index 7eb8bf7c6be..e82e40503e0 100644 --- a/src/librustc_typeck/check/wfcheck.rs +++ b/src/librustc_typeck/check/wfcheck.rs @@ -411,6 +411,23 @@ fn check_type_defn<'tcx, F>( ObligationCauseCode::MiscObligation, ) } + + // Explicit `enum` discriminant values must const-evaluate successfully. + if let Some(discr_def_id) = variant.explicit_discr { + let discr_substs = + InternalSubsts::identity_for_item(fcx.tcx, discr_def_id.to_def_id()); + + let cause = traits::ObligationCause::new( + fcx.tcx.def_span(discr_def_id), + fcx.body_id, + traits::MiscObligation, + ); + fcx.register_predicate(traits::Obligation::new( + cause, + fcx.param_env, + ty::Predicate::ConstEvaluatable(discr_def_id.to_def_id(), discr_substs), + )); + } } check_where_clauses(tcx, fcx, item.span, def_id.to_def_id(), None); @@ -1287,8 +1304,14 @@ impl ParItemLikeVisitor<'tcx> for CheckTypeWellFormedVisitor<'tcx> { /////////////////////////////////////////////////////////////////////////// // ADT +// FIXME(eddyb) replace this with getting fields/discriminants through `ty::AdtDef`. struct AdtVariant<'tcx> { + /// Types of fields in the variant, that must be well-formed. fields: Vec<AdtField<'tcx>>, + + /// Explicit discriminant of this variant (e.g. `A = 123`), + /// that must evaluate to a constant value. + explicit_discr: Option<LocalDefId>, } struct AdtField<'tcx> { @@ -1297,6 +1320,7 @@ struct AdtField<'tcx> { } impl<'a, 'tcx> FnCtxt<'a, 'tcx> { + // FIXME(eddyb) replace this with getting fields through `ty::AdtDef`. fn non_enum_variant(&self, struct_def: &hir::VariantData<'_>) -> AdtVariant<'tcx> { let fields = struct_def .fields() @@ -1309,11 +1333,20 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { AdtField { ty: field_ty, span: field.span } }) .collect(); - AdtVariant { fields } + AdtVariant { fields, explicit_discr: None } } fn enum_variants(&self, enum_def: &hir::EnumDef<'_>) -> Vec<AdtVariant<'tcx>> { - enum_def.variants.iter().map(|variant| self.non_enum_variant(&variant.data)).collect() + enum_def + .variants + .iter() + .map(|variant| AdtVariant { + fields: self.non_enum_variant(&variant.data).fields, + explicit_discr: variant + .disr_expr + .map(|explicit_discr| self.tcx.hir().local_def_id(explicit_discr.hir_id)), + }) + .collect() } fn impl_implied_bounds(&self, impl_def_id: DefId, span: Span) -> Vec<Ty<'tcx>> { |