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Fallback to other where clause if preferred is missing

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This commit is contained in:
Jack Huey 2022-02-07 12:20:09 -05:00
parent 3f504f6984
commit c920eb88b2
1 changed files with 24 additions and 8 deletions
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32
compiler/rustc_ast_lowering/src/item.rs
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@ -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),