From 0a34ce49ceab68a75dd34f1e76555396a8b5b2c8 Mon Sep 17 00:00:00 2001
From: Josh Stone <jistone@redhat.com>
Date: Tue, 13 Aug 2024 12:29:46 -0700
Subject: [PATCH 1/2] Add and use `IndexVec::append`

---
 compiler/rustc_index/src/vec.rs            | 5 +++++
 compiler/rustc_mir_transform/src/inline.rs | 4 ++--
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/compiler/rustc_index/src/vec.rs b/compiler/rustc_index/src/vec.rs
index 7438c97eb581c..1cb8bc861af98 100644
--- a/compiler/rustc_index/src/vec.rs
+++ b/compiler/rustc_index/src/vec.rs
@@ -188,6 +188,11 @@ impl<I: Idx, T> IndexVec<I, T> {
         let min_new_len = elem.index() + 1;
         self.raw.resize_with(min_new_len, fill_value);
     }
+
+    #[inline]
+    pub fn append(&mut self, other: &mut Self) {
+        self.raw.append(&mut other.raw);
+    }
 }
 
 /// `IndexVec` is often used as a map, so it provides some map-like APIs.
diff --git a/compiler/rustc_mir_transform/src/inline.rs b/compiler/rustc_mir_transform/src/inline.rs
index 324ddc5e799d5..61fc5fc881606 100644
--- a/compiler/rustc_mir_transform/src/inline.rs
+++ b/compiler/rustc_mir_transform/src/inline.rs
@@ -726,7 +726,7 @@ impl<'tcx> Inliner<'tcx> {
 
         // Insert all of the (mapped) parts of the callee body into the caller.
         caller_body.local_decls.extend(callee_body.drain_vars_and_temps());
-        caller_body.source_scopes.extend(&mut callee_body.source_scopes.drain(..));
+        caller_body.source_scopes.append(&mut callee_body.source_scopes);
         if self
             .tcx
             .sess
@@ -740,7 +740,7 @@ impl<'tcx> Inliner<'tcx> {
             // still getting consistent results from the mir-opt tests.
             caller_body.var_debug_info.append(&mut callee_body.var_debug_info);
         }
-        caller_body.basic_blocks_mut().extend(callee_body.basic_blocks_mut().drain(..));
+        caller_body.basic_blocks_mut().append(callee_body.basic_blocks_mut());
 
         caller_body[callsite.block].terminator = Some(Terminator {
             source_info: callsite.source_info,

From ce67e68cce3f4582db48b86c51a35c76d1103654 Mon Sep 17 00:00:00 2001
From: Josh Stone <jistone@redhat.com>
Date: Tue, 13 Aug 2024 16:16:57 -0700
Subject: [PATCH 2/2] Update `indexmap` and use `IndexMap::append`

---
 Cargo.lock                                      | 4 ++--
 compiler/rustc_data_structures/Cargo.toml       | 2 +-
 compiler/rustc_monomorphize/src/partitioning.rs | 4 ++--
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 4bd99b7fbe7ac..1aa0b2ea4a398 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1775,9 +1775,9 @@ checksum = "ce23b50ad8242c51a442f3ff322d56b02f08852c77e4c0b4d3fd684abc89c683"
 
 [[package]]
 name = "indexmap"
-version = "2.2.6"
+version = "2.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "168fb715dda47215e360912c096649d23d58bf392ac62f73919e831745e40f26"
+checksum = "93ead53efc7ea8ed3cfb0c79fc8023fbb782a5432b52830b6518941cebe6505c"
 dependencies = [
  "equivalent",
  "hashbrown",
diff --git a/compiler/rustc_data_structures/Cargo.toml b/compiler/rustc_data_structures/Cargo.toml
index 3794a6e043c6d..69cbf8c416105 100644
--- a/compiler/rustc_data_structures/Cargo.toml
+++ b/compiler/rustc_data_structures/Cargo.toml
@@ -10,7 +10,7 @@ bitflags = "2.4.1"
 either = "1.0"
 elsa = "=1.7.1"
 ena = "0.14.3"
-indexmap = { version = "2.0.0" }
+indexmap = { version = "2.4.0" }
 jobserver_crate = { version = "0.1.28", package = "jobserver" }
 measureme = "11"
 rustc-hash = "1.1.0"
diff --git a/compiler/rustc_monomorphize/src/partitioning.rs b/compiler/rustc_monomorphize/src/partitioning.rs
index 65a3d8d1742d9..92902185e8b75 100644
--- a/compiler/rustc_monomorphize/src/partitioning.rs
+++ b/compiler/rustc_monomorphize/src/partitioning.rs
@@ -371,7 +371,7 @@ fn merge_codegen_units<'tcx>(
         // Move the items from `cgu_src` to `cgu_dst`. Some of them may be
         // duplicate inlined items, in which case the destination CGU is
         // unaffected. Recalculate size estimates afterwards.
-        cgu_dst.items_mut().extend(cgu_src.items_mut().drain(..));
+        cgu_dst.items_mut().append(cgu_src.items_mut());
         cgu_dst.compute_size_estimate();
 
         // Record that `cgu_dst` now contains all the stuff that was in
@@ -410,7 +410,7 @@ fn merge_codegen_units<'tcx>(
         // Move the items from `smallest` to `second_smallest`. Some of them
         // may be duplicate inlined items, in which case the destination CGU is
         // unaffected. Recalculate size estimates afterwards.
-        second_smallest.items_mut().extend(smallest.items_mut().drain(..));
+        second_smallest.items_mut().append(smallest.items_mut());
         second_smallest.compute_size_estimate();
 
         // Don't update `cgu_contents`, that's only for incremental builds.