diff options
| -rw-r--r-- | compiler/rustc_ast_lowering/src/item.rs | 32 |
1 files changed, 24 insertions, 8 deletions
diff --git a/compiler/rustc_ast_lowering/src/item.rs b/compiler/rustc_ast_lowering/src/item.rs index 77c5797442a..b452290dff4 100644 --- a/compiler/rustc_ast_lowering/src/item.rs +++ b/compiler/rustc_ast_lowering/src/item.rs @@ -25,6 +25,26 @@ pub(super) struct ItemLowerer<'a, 'lowering, 'hir> { pub(super) lctx: &'a mut LoweringContext<'lowering, 'hir>, } +/// When we have a ty alias we *may* have two where clauses. To give the best diagnostics, we set the span +/// to the where clause that is prefered, if it exists. Otherwise, it sets the span to the other where +/// clause if it exists. +fn add_ty_alias_where_clause( + generics: &mut ast::Generics, + mut where_clauses: (TyAliasWhereClause, TyAliasWhereClause), + prefer_first: bool, +) { + if !prefer_first { + where_clauses = (where_clauses.1, where_clauses.0); + } + if where_clauses.0.0 || !where_clauses.1.0 { + generics.where_clause.has_where_token = where_clauses.0.0; + generics.where_clause.span = where_clauses.0.1; + } else { + generics.where_clause.has_where_token = where_clauses.1.0; + generics.where_clause.span = where_clauses.1.1; + } +} + impl ItemLowerer<'_, '_, '_> { fn with_trait_impl_ref<T>( &mut self, @@ -298,8 +318,7 @@ impl<'hir> LoweringContext<'_, 'hir> { }, ); let mut generics = generics.clone(); - generics.where_clause.has_where_token = where_clauses.0.0; - generics.where_clause.span = where_clauses.0.1; + add_ty_alias_where_clause(&mut generics, where_clauses, true); let generics = self.lower_generics( &generics, ImplTraitContext::Disallowed(ImplTraitPosition::Generic), @@ -311,8 +330,7 @@ impl<'hir> LoweringContext<'_, 'hir> { }) => { let ty = self.arena.alloc(self.ty(span, hir::TyKind::Err)); let mut generics = generics.clone(); - generics.where_clause.has_where_token = where_clauses.0.0; - generics.where_clause.span = where_clauses.0.1; + add_ty_alias_where_clause(&mut generics, *where_clauses, true); let generics = self.lower_generics( &generics, ImplTraitContext::Disallowed(ImplTraitPosition::Generic), @@ -856,8 +874,7 @@ impl<'hir> LoweringContext<'_, 'hir> { self.lower_ty(x, ImplTraitContext::Disallowed(ImplTraitPosition::Type)) }); let mut generics = generics.clone(); - generics.where_clause.has_where_token = where_clauses.1.0; - generics.where_clause.span = where_clauses.1.1; + add_ty_alias_where_clause(&mut generics, where_clauses, false); let generics = self.lower_generics( &generics, ImplTraitContext::Disallowed(ImplTraitPosition::Generic), @@ -941,8 +958,7 @@ impl<'hir> LoweringContext<'_, 'hir> { } AssocItemKind::TyAlias(box TyAlias { generics, where_clauses, ty, .. }) => { let mut generics = generics.clone(); - generics.where_clause.has_where_token = where_clauses.1.0; - generics.where_clause.span = where_clauses.1.1; + add_ty_alias_where_clause(&mut generics, *where_clauses, false); let generics = self.lower_generics( &generics, ImplTraitContext::Disallowed(ImplTraitPosition::Generic), |