From: Arthur Cohen <arthur.cohen@embecosm.com>
Date: Thu, 2 Jan 2025 10:56:11 +0000 (+0000)
Subject: gccrs: derive(Clone): Add note about Clone::clone()
X-Git-Tag: basepoints/gcc-16~919
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=72ad259a22c182756b883871285f7c30e7c778cb;p=thirdparty%2Fgcc.git

gccrs: derive(Clone): Add note about Clone::clone()

gcc/rust/ChangeLog:

	* expand/rust-derive-clone.cc (DeriveClone::clone_call): Mention using `clone_fn`
	lang item in the future.
---

diff --git a/gcc/rust/expand/rust-derive-clone.cc b/gcc/rust/expand/rust-derive-clone.cc
index 2f733fae910..b8c92dcc6fe 100644
--- a/gcc/rust/expand/rust-derive-clone.cc
+++ b/gcc/rust/expand/rust-derive-clone.cc
@@ -30,6 +30,15 @@ DeriveClone::clone_call (std::unique_ptr<Expr> &&to_clone)
   // $crate::core::clone::Clone::clone for the fully qualified path - we don't
   // link with `core` yet so that might be an issue. Use `Clone::clone` for now?
   // TODO: Factor this function inside the DeriveAccumulator
+
+  // Interestingly, later versions of Rust have a `clone_fn` lang item which
+  // corresponds to this. But because we are first targeting 1.49, we cannot use
+  // it yet. Once we target a new, more recent version of the language, we'll
+  // have figured out how to compile and distribute `core`, meaning we'll be
+  // able to directly call `::core::clone::Clone::clone()`
+
+  // Not sure how to call it properly in the meantime...
+
   auto path = std::unique_ptr<Expr> (
     new PathInExpression (builder.path_in_expression ({"Clone", "clone"})));
 
@@ -79,10 +88,7 @@ DeriveClone::clone_impl (
   std::unique_ptr<AssociatedItem> &&clone_fn, std::string name,
   const std::vector<std::unique_ptr<GenericParam>> &type_generics)
 {
-  // should that be `$crate::core::clone::Clone` instead?
-  auto segments = std::vector<std::unique_ptr<TypePathSegment>> ();
-  segments.emplace_back (builder.type_path_segment ("Clone"));
-  auto clone = TypePath (std::move (segments), loc);
+  auto clone = builder.type_path (LangItem::Kind::CLONE);
 
   auto trait_items = std::vector<std::unique_ptr<AssociatedItem>> ();
   trait_items.emplace_back (std::move (clone_fn));