Don't populate rust_ir::AdtVariantDatum::fields for now due to perf

Author: Veykril

crates/hir-ty/src/chalk_db.rs

@@ -742,6 +742,8 @@ pub(crate) fn adt_datum_query(
         phantom_data,
     };
 
+    #[cfg(FALSE)]
+    // this slows down rust-analyzer by quite a bit unfortunately, so enabling this is currently not worth it
     let variant_id_to_fields = |id: VariantId| {
         let variant_data = &id.variant_data(db.upcast());
         let fields = if variant_data.fields().is_empty() {
@@ -757,6 +759,7 @@ pub(crate) fn adt_datum_query(
         };
         rust_ir::AdtVariantDatum { fields }
     };
+    let variant_id_to_fields = |_: VariantId| rust_ir::AdtVariantDatum { fields: vec![] };
 
     let (kind, variants) = match adt_id {
         hir_def::AdtId::StructId(id) => {