Rollup merge of #129067 - cuviper:append, r=wesleywiser

Use `append` instead of `extend(drain(..))`

The first commit adds `IndexVec::append` that forwards to `Vec::append`, and uses it in a couple places.

The second commit updates `indexmap` for its new `IndexMap::append`, and also uses that in a couple places.

These changes are similar to what [`clippy::extend_with_drain`](https://rust-lang.github.io/rust-clippy/master/index.html#/extend_with_drain) would suggest, just for other collection types.

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",

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"

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.

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,

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.