Rename some Cache type variables as C.

Currently type variables that impl `QueryCache` are called either `C` or
`Cache`. I find the former clearer because single char type variables
names are very common and longer type variable names are easy to mistake
for type or trait names -- e.g. I find the trait bound `C: QueryCache`
much easier and faster to read than `Cache: QueryCache`.

Author: nnethercote

compiler/rustc_middle/src/query/inner.rs

@@ -33,15 +33,15 @@ where
 /// Shared implementation of `tcx.$query(..)` and `tcx.at(span).$query(..)`
 /// for all queries.
 #[inline(always)]
-pub(crate) fn query_get_at<'tcx, Cache>(
+pub(crate) fn query_get_at<'tcx, C>(
     tcx: TyCtxt<'tcx>,
-    execute_query: fn(TyCtxt<'tcx>, Span, Cache::Key, QueryMode) -> Option<Cache::Value>,
-    query_cache: &Cache,
+    execute_query: fn(TyCtxt<'tcx>, Span, C::Key, QueryMode) -> Option<C::Value>,
+    query_cache: &C,
     span: Span,
-    key: Cache::Key,
-) -> Cache::Value
+    key: C::Key,
+) -> C::Value
 where
-    Cache: QueryCache,
+    C: QueryCache,
 {
     match try_get_cached(tcx, query_cache, &key) {
         Some(value) => value,
@@ -52,14 +52,14 @@ where
 /// Shared implementation of `tcx.ensure_ok().$query(..)` for most queries,
 /// and `tcx.ensure_done().$query(..)` for all queries.
 #[inline]
-pub(crate) fn query_ensure<'tcx, Cache>(
+pub(crate) fn query_ensure<'tcx, C>(
     tcx: TyCtxt<'tcx>,
-    execute_query: fn(TyCtxt<'tcx>, Span, Cache::Key, QueryMode) -> Option<Cache::Value>,
-    query_cache: &Cache,
-    key: Cache::Key,
+    execute_query: fn(TyCtxt<'tcx>, Span, C::Key, QueryMode) -> Option<C::Value>,
+    query_cache: &C,
+    key: C::Key,
     ensure_mode: EnsureMode,
 ) where
-    Cache: QueryCache,
+    C: QueryCache,
 {
     if try_get_cached(tcx, query_cache, &key).is_none() {
         execute_query(tcx, DUMMY_SP, key, QueryMode::Ensure { ensure_mode });
@@ -69,17 +69,17 @@ pub(crate) fn query_ensure<'tcx, Cache>(
 /// Shared implementation of `tcx.ensure_ok().$query(..)` for queries that
 /// have the `return_result_from_ensure_ok` modifier.
 #[inline]
-pub(crate) fn query_ensure_error_guaranteed<'tcx, Cache, T>(
+pub(crate) fn query_ensure_error_guaranteed<'tcx, C, T>(
     tcx: TyCtxt<'tcx>,
-    execute_query: fn(TyCtxt<'tcx>, Span, Cache::Key, QueryMode) -> Option<Cache::Value>,
-    query_cache: &Cache,
-    key: Cache::Key,
+    execute_query: fn(TyCtxt<'tcx>, Span, C::Key, QueryMode) -> Option<C::Value>,
+    query_cache: &C,
+    key: C::Key,
     // This arg is needed to match the signature of `query_ensure`,
     // but should always be `EnsureMode::Ok`.
     ensure_mode: EnsureMode,
 ) -> Result<(), ErrorGuaranteed>
 where
-    Cache: QueryCache<Value = Erased<Result<T, ErrorGuaranteed>>>,
+    C: QueryCache<Value = Erased<Result<T, ErrorGuaranteed>>>,
     Result<T, ErrorGuaranteed>: Erasable,
 {
     assert_matches!(ensure_mode, EnsureMode::Ok);
@@ -101,15 +101,15 @@ where
 }
 
 /// Common implementation of query feeding, used by `define_feedable!`.
-pub(crate) fn query_feed<'tcx, Cache>(
+pub(crate) fn query_feed<'tcx, C>(
     tcx: TyCtxt<'tcx>,
     dep_kind: DepKind,
-    query_vtable: &QueryVTable<'tcx, Cache>,
-    key: Cache::Key,
-    value: Cache::Value,
+    query_vtable: &QueryVTable<'tcx, C>,
+    key: C::Key,
+    value: C::Value,
 ) where
-    Cache: QueryCache,
-    Cache::Key: DepNodeKey<'tcx>,
+    C: QueryCache,
+    C::Key: DepNodeKey<'tcx>,
 {
     let format_value = query_vtable.format_value;
 

compiler/rustc_query_impl/src/plumbing.rs

@@ -306,15 +306,15 @@ where
     QueryStackFrameExtra::new(description, span, def_kind)
 }
 
-pub(crate) fn create_deferred_query_stack_frame<'tcx, Cache>(
+pub(crate) fn create_deferred_query_stack_frame<'tcx, C>(
     tcx: TyCtxt<'tcx>,
-    vtable: &'tcx QueryVTable<'tcx, Cache>,
-    key: Cache::Key,
+    vtable: &'tcx QueryVTable<'tcx, C>,
+    key: C::Key,
 ) -> QueryStackFrame<QueryStackDeferred<'tcx>>
 where
-    Cache: QueryCache,
-    Cache::Key: Key + DynSend + DynSync,
-    QueryVTable<'tcx, Cache>: DynSync,
+    C: QueryCache,
+    C::Key: Key + DynSend + DynSync,
+    QueryVTable<'tcx, C>: DynSync,
 {
     let kind = vtable.dep_kind;