move QueryKeyStringCache from rustc_middle to rustc_query_impl, where it actually used

also allows to drop measureme dep on rustc_middle

compiler/rustc_query_impl/src/lib.rs

@@ -13,6 +13,7 @@
 extern crate rustc_middle;
 
 use crate::plumbing::{__rust_begin_short_backtrace, encode_all_query_results, try_mark_green};
+use crate::profiling_support::QueryKeyStringCache;
 use field_offset::offset_of;
 use rustc_data_structures::stable_hasher::HashStable;
 use rustc_data_structures::sync::AtomicU64;
@@ -21,9 +22,7 @@ use rustc_middle::dep_graph::DepNodeIndex;
 use rustc_middle::dep_graph::{self, DepKind, DepKindStruct};
 use rustc_middle::query::erase::{erase, restore, Erase};
 use rustc_middle::query::on_disk_cache::{CacheEncoder, EncodedDepNodeIndex, OnDiskCache};
-use rustc_middle::query::plumbing::{
-    DynamicQuery, QueryKeyStringCache, QuerySystem, QuerySystemFns,
-};
+use rustc_middle::query::plumbing::{DynamicQuery, QuerySystem, QuerySystemFns};
 use rustc_middle::query::AsLocalKey;
 use rustc_middle::query::{
     queries, DynamicQueries, ExternProviders, Providers, QueryCaches, QueryEngine, QueryStates,

compiler/rustc_query_impl/src/profiling_support.rs

@@ -1,13 +1,23 @@
 use measureme::{StringComponent, StringId};
+use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::profiling::SelfProfiler;
 use rustc_hir::def_id::{CrateNum, DefId, DefIndex, LocalDefId, LOCAL_CRATE};
 use rustc_hir::definitions::DefPathData;
-use rustc_middle::query::plumbing::QueryKeyStringCache;
 use rustc_middle::ty::TyCtxt;
 use rustc_query_system::query::QueryCache;
 use std::fmt::Debug;
 use std::io::Write;
 
+pub(crate) struct QueryKeyStringCache {
+    def_id_cache: FxHashMap<DefId, StringId>,
+}
+
+impl QueryKeyStringCache {
+    fn new() -> QueryKeyStringCache {
+        QueryKeyStringCache { def_id_cache: Default::default() }
+    }
+}
+
 struct QueryKeyStringBuilder<'p, 'tcx> {
     profiler: &'p SelfProfiler,
     tcx: TyCtxt<'tcx>,