Save 2 pointers in `TerminatorKind` (96 → 80 bytes)

These things don't need to be `Vec`s; boxed slices are enough.

The frequent one here is call arguments, but MIR building knows the number of arguments from the THIR, so the collect is always getting the allocation right in the first place, and thus this shouldn't ever add the shrink-in-place overhead.

1 files changed, 7 insertions, 6 deletions

diff --git a/compiler/rustc_mir_transform/src/inline.rs b/compiler/rustc_mir_transform/src/inline.rs
index 32b5d812025..0a5fc697d03 100644
--- a/compiler/rustc_mir_transform/src/inline.rs
+++ b/compiler/rustc_mir_transform/src/inline.rs
@@ -624,8 +624,7 @@ impl<'tcx> Inliner<'tcx> {
         };
 
         // Copy the arguments if needed.
-        let args: Vec<_> =
-            self.make_call_args(args, &callsite, caller_body, &callee_body, return_block);
+        let args = self.make_call_args(args, &callsite, caller_body, &callee_body, return_block);
 
         let mut integrator = Integrator {
             args: &args,
@@ -736,12 +735,12 @@ impl<'tcx> Inliner<'tcx> {
 
     fn make_call_args(
         &self,
-        args: Vec<Spanned<Operand<'tcx>>>,
+        args: Box<[Spanned<Operand<'tcx>>]>,
         callsite: &CallSite<'tcx>,
         caller_body: &mut Body<'tcx>,
         callee_body: &Body<'tcx>,
         return_block: Option<BasicBlock>,
-    ) -> Vec<Local> {
+    ) -> Box<[Local]> {
         let tcx = self.tcx;
 
         // There is a bit of a mismatch between the *caller* of a closure and the *callee*.
@@ -768,7 +767,8 @@ impl<'tcx> Inliner<'tcx> {
         //
         // and the vector is `[closure_ref, tmp0, tmp1, tmp2]`.
         if callsite.fn_sig.abi() == Abi::RustCall && callee_body.spread_arg.is_none() {
-            let mut args = args.into_iter();
+            // FIXME(edition_2024): switch back to a normal method call.
+            let mut args = <_>::into_iter(args);
             let self_ = self.create_temp_if_necessary(
                 args.next().unwrap().node,
                 callsite,
@@ -802,7 +802,8 @@ impl<'tcx> Inliner<'tcx> {
 
             closure_ref_arg.chain(tuple_tmp_args).collect()
         } else {
-            args.into_iter()
+            // FIXME(edition_2024): switch back to a normal method call.
+            <_>::into_iter(args)
                 .map(|a| self.create_temp_if_necessary(a.node, callsite, caller_body, return_block))
                 .collect()
         }