Make iteration order of trimmed_def_paths query stable

Author: michaelwoerister

compiler/rustc_middle/src/query/mod.rs

@@ -1791,7 +1791,7 @@ rustc_queries! {
     }
     /// Collects the "trimmed", shortest accessible paths to all items for diagnostics.
     /// See the [provider docs](`rustc_middle::ty::print::trimmed_def_paths`) for more info.
-    query trimmed_def_paths(_: ()) -> &'tcx FxHashMap<DefId, Symbol> {
+    query trimmed_def_paths(_: ()) -> &'tcx DefIdMap<Symbol> {
         arena_cache
         desc { "calculating trimmed def paths" }
     }

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

@@ -12,7 +12,7 @@ use rustc_apfloat::Float;
 use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
 use rustc_hir as hir;
 use rustc_hir::def::{self, CtorKind, DefKind, Namespace};
-use rustc_hir::def_id::{DefIdSet, ModDefId, CRATE_DEF_ID, LOCAL_CRATE};
+use rustc_hir::def_id::{DefIdMap, DefIdSet, ModDefId, CRATE_DEF_ID, LOCAL_CRATE};
 use rustc_hir::definitions::{DefKey, DefPathDataName};
 use rustc_hir::LangItem;
 use rustc_session::config::TrimmedDefPaths;
@@ -3049,8 +3049,8 @@ fn for_each_def(tcx: TyCtxt<'_>, mut collect_fn: impl for<'b> FnMut(&'b Ident, N
 ///
 /// See also [`DelayDm`](rustc_error_messages::DelayDm) and [`with_no_trimmed_paths!`].
 // this is pub to be able to intra-doc-link it
-pub fn trimmed_def_paths(tcx: TyCtxt<'_>, (): ()) -> FxHashMap<DefId, Symbol> {
-    let mut map: FxHashMap<DefId, Symbol> = FxHashMap::default();
+pub fn trimmed_def_paths(tcx: TyCtxt<'_>, (): ()) -> DefIdMap<Symbol> {
+    let mut map: DefIdMap<Symbol> = Default::default();
 
     if let TrimmedDefPaths::GoodPath = tcx.sess.opts.trimmed_def_paths {
         // Trimming paths is expensive and not optimized, since we expect it to only be used for error reporting.