Auto merge of #123126 - oli-obk:feed_crate_num, r=davidtwco

Enable `CrateNum` query feeding via `TyCtxt`

Instead of having a magic function that violates some `TyCtxtFeed` invariants, add a `create_def` equivalent for `CrateNum`s.

Note that this still isn't tracked by the query system (unlike `create_def`), and that feeding most `CrateNum` queries for crates other than the local one will likely cause performance regressions.

These things should be attempted on their own separately, but this PR should stand on its own

1 files changed, 19 insertions, 8 deletions

diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 686aa9cdc04..7dbe59e132d 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -565,13 +565,6 @@ impl<'tcx> TyCtxt<'tcx> {
         TyCtxtFeed { tcx: self, key: () }
     }
 
-    /// Can only be fed before queries are run, and is thus exempt from any
-    /// incremental issues. Do not use except for the initial query feeding.
-    pub fn feed_local_crate(self) -> TyCtxtFeed<'tcx, CrateNum> {
-        self.dep_graph.assert_ignored();
-        TyCtxtFeed { tcx: self, key: LOCAL_CRATE }
-    }
-
     /// Only used in the resolver to register the `CRATE_DEF_ID` `DefId` and feed
     /// some queries for it. It will panic if used twice.
     pub fn create_local_crate_def_id(self, span: Span) -> TyCtxtFeed<'tcx, LocalDefId> {
@@ -1151,7 +1144,12 @@ impl<'tcx> TyCtxt<'tcx> {
         if stable_crate_id == self.stable_crate_id(LOCAL_CRATE) {
             LOCAL_CRATE
         } else {
-            self.cstore_untracked().stable_crate_id_to_crate_num(stable_crate_id)
+            *self
+                .untracked()
+                .stable_crate_ids
+                .read()
+                .get(&stable_crate_id)
+                .unwrap_or_else(|| bug!("uninterned StableCrateId: {stable_crate_id:?}"))
         }
     }
 
@@ -1267,6 +1265,19 @@ impl<'tcx> TyCtxt<'tcx> {
         feed
     }
 
+    pub fn create_crate_num(
+        self,
+        stable_crate_id: StableCrateId,
+    ) -> Result<TyCtxtFeed<'tcx, CrateNum>, CrateNum> {
+        if let Some(&existing) = self.untracked().stable_crate_ids.read().get(&stable_crate_id) {
+            return Err(existing);
+        }
+
+        let num = CrateNum::new(self.untracked().stable_crate_ids.read().len());
+        self.untracked().stable_crate_ids.write().insert(stable_crate_id, num);
+        Ok(TyCtxtFeed { key: num, tcx: self })
+    }
+
     pub fn iter_local_def_id(self) -> impl Iterator<Item = LocalDefId> + 'tcx {
         // Create a dependency to the red node to be sure we re-execute this when the amount of
         // definitions change.