Allow the lint somewhere because precautios is already taken.

Author: ismailarilik

compiler/rustc_middle/src/ty/print/pretty.rs

@@ -5,7 +5,7 @@ use std::ops::{Deref, DerefMut};
 
 use rustc_apfloat::Float;
 use rustc_apfloat::ieee::{Double, Half, Quad, Single};
-use rustc_data_structures::fx::{FxIndexMap, IndexEntry};
+use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
 use rustc_data_structures::unord::UnordMap;
 use rustc_hir as hir;
 use rustc_hir::LangItem;
@@ -3352,8 +3352,8 @@ pub fn trimmed_def_paths(tcx: TyCtxt<'_>, (): ()) -> DefIdMap<Symbol> {
 
     // Once constructed, unique namespace+symbol pairs will have a `Some(_)` entry, while
     // non-unique pairs will have a `None` entry.
-    let unique_symbols_rev: &mut FxIndexMap<(Namespace, Symbol), Option<DefId>> =
-        &mut FxIndexMap::default();
+    let unique_symbols_rev: &mut FxHashMap<(Namespace, Symbol), Option<DefId>> =
+        &mut FxHashMap::default();
 
     for symbol_set in tcx.resolutions(()).glob_map.values() {
         for symbol in symbol_set {
@@ -3363,23 +3363,29 @@ pub fn trimmed_def_paths(tcx: TyCtxt<'_>, (): ()) -> DefIdMap<Symbol> {
         }
     }
 
-    for_each_def(tcx, |ident, ns, def_id| match unique_symbols_rev.entry((ns, ident.name)) {
-        IndexEntry::Occupied(mut v) => match v.get() {
-            None => {}
-            Some(existing) => {
-                if *existing != def_id {
-                    v.insert(None);
+    for_each_def(tcx, |ident, ns, def_id| {
+        use std::collections::hash_map::Entry::{Occupied, Vacant};
+
+        match unique_symbols_rev.entry((ns, ident.name)) {
+            Occupied(mut v) => match v.get() {
+                None => {}
+                Some(existing) => {
+                    if *existing != def_id {
+                        v.insert(None);
+                    }
                 }
+            },
+            Vacant(v) => {
+                v.insert(Some(def_id));
             }
-        },
-        IndexEntry::Vacant(v) => {
-            v.insert(Some(def_id));
         }
     });
 
     // Put the symbol from all the unique namespace+symbol pairs into `map`.
     let mut map: DefIdMap<Symbol> = Default::default();
-    for ((_, symbol), opt_def_id) in unique_symbols_rev.drain(..) {
+    // Precatious is taken below in the loop so we can allow this lint here.
+    #[allow(rustc::potential_query_instability)]
+    for ((_, symbol), opt_def_id) in unique_symbols_rev.drain() {
         use std::collections::hash_map::Entry::{Occupied, Vacant};
 
         if let Some(def_id) = opt_def_id {