From 2bc723fbcaa1c1136793dd92f1b4307335184007 Mon Sep 17 00:00:00 2001
From: Santiago Pastorino <spastorino@gmail.com>
Date: Fri, 4 Jun 2021 16:15:31 -0300
Subject: [PATCH] Change opaque type map to be a `VecMap`

---
 compiler/rustc_mir/src/borrow_check/type_check/mod.rs | 2 +-
 compiler/rustc_trait_selection/src/opaque_types.rs    | 9 +++++----
 compiler/rustc_typeck/src/check/inherited.rs          | 5 +++--
 compiler/rustc_typeck/src/check/writeback.rs          | 2 +-
 4 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/compiler/rustc_mir/src/borrow_check/type_check/mod.rs b/compiler/rustc_mir/src/borrow_check/type_check/mod.rs
index e294f128f2e14..4b9569b74b904 100644
--- a/compiler/rustc_mir/src/borrow_check/type_check/mod.rs
+++ b/compiler/rustc_mir/src/borrow_check/type_check/mod.rs
@@ -1281,7 +1281,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                             .eq(output_ty, revealed_ty)?,
                     );
 
-                    for (&opaque_def_id, opaque_decl) in &opaque_type_map {
+                    for &(opaque_def_id, opaque_decl) in &opaque_type_map {
                         let resolved_ty = infcx.resolve_vars_if_possible(opaque_decl.concrete_ty);
                         let concrete_is_opaque = if let ty::Opaque(def_id, _) = resolved_ty.kind() {
                             *def_id == opaque_def_id
diff --git a/compiler/rustc_trait_selection/src/opaque_types.rs b/compiler/rustc_trait_selection/src/opaque_types.rs
index 163df26e9ffaf..2fdb267d0db8f 100644
--- a/compiler/rustc_trait_selection/src/opaque_types.rs
+++ b/compiler/rustc_trait_selection/src/opaque_types.rs
@@ -2,8 +2,9 @@ use crate::infer::InferCtxtExt as _;
 use crate::traits::{self, PredicateObligation};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::sync::Lrc;
+use rustc_data_structures::vec_map::VecMap;
 use rustc_hir as hir;
-use rustc_hir::def_id::{DefId, DefIdMap, LocalDefId};
+use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::Node;
 use rustc_infer::infer::error_reporting::unexpected_hidden_region_diagnostic;
 use rustc_infer::infer::free_regions::FreeRegionRelations;
@@ -16,7 +17,7 @@ use rustc_span::Span;
 
 use std::ops::ControlFlow;
 
-pub type OpaqueTypeMap<'tcx> = DefIdMap<OpaqueTypeDecl<'tcx>>;
+pub type OpaqueTypeMap<'tcx> = VecMap<DefId, OpaqueTypeDecl<'tcx>>;
 
 /// Information about the opaque types whose values we
 /// are inferring in this function (these are the `impl Trait` that
@@ -370,10 +371,10 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
     ) {
         debug!("constrain_opaque_types()");
 
-        for (&def_id, opaque_defn) in opaque_types {
+        for &(def_id, opaque_defn) in opaque_types {
             self.constrain_opaque_type(
                 def_id,
-                opaque_defn,
+                &opaque_defn,
                 GenerateMemberConstraints::WhenRequired,
                 free_region_relations,
             );
diff --git a/compiler/rustc_typeck/src/check/inherited.rs b/compiler/rustc_typeck/src/check/inherited.rs
index 1dacbade1bd32..0ff9bed749c75 100644
--- a/compiler/rustc_typeck/src/check/inherited.rs
+++ b/compiler/rustc_typeck/src/check/inherited.rs
@@ -2,8 +2,9 @@ use super::callee::DeferredCallResolution;
 use super::MaybeInProgressTables;
 
 use rustc_data_structures::fx::FxHashMap;
+use rustc_data_structures::vec_map::VecMap;
 use rustc_hir as hir;
-use rustc_hir::def_id::{DefIdMap, LocalDefId};
+use rustc_hir::def_id::{DefId, DefIdMap, LocalDefId};
 use rustc_hir::HirIdMap;
 use rustc_infer::infer;
 use rustc_infer::infer::{InferCtxt, InferOk, TyCtxtInferExt};
@@ -58,7 +59,7 @@ pub struct Inherited<'a, 'tcx> {
     // associated fresh inference variable. Writeback resolves these
     // variables to get the concrete type, which can be used to
     // 'de-opaque' OpaqueTypeDecl, after typeck is done with all functions.
-    pub(super) opaque_types: RefCell<DefIdMap<OpaqueTypeDecl<'tcx>>>,
+    pub(super) opaque_types: RefCell<VecMap<DefId, OpaqueTypeDecl<'tcx>>>,
 
     /// A map from inference variables created from opaque
     /// type instantiations (`ty::Infer`) to the actual opaque
diff --git a/compiler/rustc_typeck/src/check/writeback.rs b/compiler/rustc_typeck/src/check/writeback.rs
index e472add6e80f3..685f81b3bd6a5 100644
--- a/compiler/rustc_typeck/src/check/writeback.rs
+++ b/compiler/rustc_typeck/src/check/writeback.rs
@@ -475,7 +475,7 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
     }
 
     fn visit_opaque_types(&mut self, span: Span) {
-        for (&def_id, opaque_defn) in self.fcx.opaque_types.borrow().iter() {
+        for &(def_id, opaque_defn) in self.fcx.opaque_types.borrow().iter() {
             let hir_id = self.tcx().hir().local_def_id_to_hir_id(def_id.expect_local());
             let instantiated_ty = self.resolve(opaque_defn.concrete_ty, &hir_id);