From 31174e403c74194cfbe6d2ab4c1a160df6b6062f Mon Sep 17 00:00:00 2001
From: Noratrieb <48135649+Noratrieb@users.noreply.github.com>
Date: Sat, 4 Oct 2025 22:15:02 +0200
Subject: [PATCH] Avoid `LocalCopy` instantiation for `#[inline]` on
 `-Copt-level=0`

Because it is not really helpful to have downstream instantiations that
we won't inline anyways (`*`)

`*` This is not quite true when `#[inline]` is being used as effectively
`#[likely_unused]`
---
 compiler/rustc_mir_transform/src/cross_crate_inline.rs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/compiler/rustc_mir_transform/src/cross_crate_inline.rs b/compiler/rustc_mir_transform/src/cross_crate_inline.rs
index df98c07f54958..9a0e4c432b43b 100644
--- a/compiler/rustc_mir_transform/src/cross_crate_inline.rs
+++ b/compiler/rustc_mir_transform/src/cross_crate_inline.rs
@@ -46,7 +46,9 @@ fn cross_crate_inlinable(tcx: TyCtxt<'_>, def_id: LocalDefId) -> bool {
     // #[inline(never)] to force code generation.
     match codegen_fn_attrs.inline {
         InlineAttr::Never => return false,
-        InlineAttr::Hint | InlineAttr::Always | InlineAttr::Force { .. } => return true,
+        // For -Copt-level=0, we won't inline functions anyways, so there's no reason to codegen them as LocalCopy.
+        InlineAttr::Hint if tcx.sess.opts.optimize != OptLevel::No => return true,
+        InlineAttr::Always | InlineAttr::Force { .. } => return true,
         _ => {}
     }