Only create `OnDiskCache` in incremental compilation mode

This lets us skip doing useless work when we're not in incremental
compilation mode.

1 files changed, 4 insertions, 4 deletions

diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index 634d50368bd..175b108dd24 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -130,8 +130,8 @@ rustc_queries! {
             storage(ArenaCacheSelector<'tcx>)
             cache_on_disk_if { key.is_local() }
             load_cached(tcx, id) {
-                let generics: Option<ty::Generics> = tcx.queries.on_disk_cache
-                                                        .try_load_query_result(tcx, id);
+                let generics: Option<ty::Generics> = tcx.queries.on_disk_cache.as_ref()
+                                                        .and_then(|c| c.try_load_query_result(tcx, id));
                 generics
             }
         }
@@ -688,8 +688,8 @@ rustc_queries! {
             cache_on_disk_if { true }
             load_cached(tcx, id) {
                 let typeck_results: Option<ty::TypeckResults<'tcx>> = tcx
-                    .queries.on_disk_cache
-                    .try_load_query_result(tcx, id);
+                    .queries.on_disk_cache.as_ref()
+                    .and_then(|c| c.try_load_query_result(tcx, id));
 
                 typeck_results.map(|x| &*tcx.arena.alloc(x))
             }