derive(PartialEq): Also derive StructuralPartialEq

gcc/rust/ChangeLog:

	* expand/rust-derive-partial-eq.cc: Adapt signatures to generate two impls.
	* expand/rust-derive-partial-eq.h: Likewise.
	* expand/rust-derive.cc (DeriveVisitor::derive): Adapt to multiple item generation.

gcc/testsuite/ChangeLog:

	* rust/compile/derive-eq-invalid.rs: Declare StructuralPartialEq.
	* rust/compile/derive-partialeq1.rs: Likewise.
	* rust/execute/torture/derive-partialeq1.rs: Likewise.

6 files changed, 44 insertions, 23 deletions

diff --git a/gcc/rust/expand/rust-derive-partial-eq.cc b/gcc/rust/expand/rust-derive-partial-eq.cc
index 6f7ef7d..ff66faa 100644
--- a/gcc/rust/expand/rust-derive-partial-eq.cc
+++ b/gcc/rust/expand/rust-derive-partial-eq.cc
@@ -1,4 +1,4 @@
-// Copyright (C) 2020-2024 Free Software Foundation, Inc.
+// Copyright (C) 2025 Free Software Foundation, Inc.
 
 // This file is part of GCC.
 
@@ -27,35 +27,40 @@
 
 namespace Rust {
 namespace AST {
-DerivePartialEq::DerivePartialEq (location_t loc)
-  : DeriveVisitor (loc), expanded (nullptr)
-{}
+DerivePartialEq::DerivePartialEq (location_t loc) : DeriveVisitor (loc) {}
 
-std::unique_ptr<AST::Item>
+std::vector<std::unique_ptr<AST::Item>>
 DerivePartialEq::go (Item &item)
 {
   item.accept_vis (*this);
 
-  rust_assert (expanded);
-
   return std::move (expanded);
 }
 
-std::unique_ptr<Item>
-DerivePartialEq::partial_eq_impl (
+std::vector<std::unique_ptr<Item>>
+DerivePartialEq::partialeq_impls (
   std::unique_ptr<AssociatedItem> &&eq_fn, std::string name,
   const std::vector<std::unique_ptr<GenericParam>> &type_generics)
 {
   auto eq = builder.type_path (LangItem::Kind::EQ);
+  auto speq = builder.type_path (LangItem::Kind::STRUCTURAL_PEQ);
 
   auto trait_items = vec (std::move (eq_fn));
 
-  auto generics
+  // no extra bound on StructuralPeq
+  auto peq_generics
     = setup_impl_generics (name, type_generics, builder.trait_bound (eq));
+  auto speq_generics = setup_impl_generics (name, type_generics);
+
+  auto peq = builder.trait_impl (eq, std::move (peq_generics.self_type),
+				 std::move (trait_items),
+				 std::move (peq_generics.impl));
+
+  auto structural_peq
+    = builder.trait_impl (speq, std::move (speq_generics.self_type), {},
+			  std::move (speq_generics.impl));
 
-  return builder.trait_impl (eq, std::move (generics.self_type),
-			     std::move (trait_items),
-			     std::move (generics.impl));
+  return vec (std::move (peq), std::move (structural_peq));
 }
 
 std::unique_ptr<AssociatedItem>
@@ -137,7 +142,7 @@ DerivePartialEq::visit_tuple (TupleStruct &item)
   auto fn = eq_fn (build_eq_expression (std::move (fields)), type_name);
 
   expanded
-    = partial_eq_impl (std::move (fn), type_name, item.get_generic_params ());
+    = partialeq_impls (std::move (fn), type_name, item.get_generic_params ());
 }
 
 void
@@ -153,7 +158,7 @@ DerivePartialEq::visit_struct (StructStruct &item)
   auto fn = eq_fn (build_eq_expression (std::move (fields)), type_name);
 
   expanded
-    = partial_eq_impl (std::move (fn), type_name, item.get_generic_params ());
+    = partialeq_impls (std::move (fn), type_name, item.get_generic_params ());
 }
 
 MatchCase
@@ -250,11 +255,12 @@ void
 DerivePartialEq::visit_enum (Enum &item)
 {
   auto cases = std::vector<MatchCase> ();
+  auto type_name = item.get_identifier ().as_string ();
 
   for (auto &variant : item.get_variants ())
     {
       auto variant_path
-	= builder.variant_path (item.get_identifier ().as_string (),
+	= builder.variant_path (type_name,
 				variant->get_identifier ().as_string ());
 
       switch (variant->get_enum_item_kind ())
@@ -290,11 +296,10 @@ DerivePartialEq::visit_enum (Enum &item)
 					 builder.identifier ("other"))),
 		     std::move (cases));
 
-  auto fn = eq_fn (std::move (match), item.get_identifier ().as_string ());
+  auto fn = eq_fn (std::move (match), type_name);
 
   expanded
-    = partial_eq_impl (std::move (fn), item.get_identifier ().as_string (),
-		       item.get_generic_params ());
+    = partialeq_impls (std::move (fn), type_name, item.get_generic_params ());
 }
 
 void
diff --git a/gcc/rust/expand/rust-derive-partial-eq.h b/gcc/rust/expand/rust-derive-partial-eq.h
index 2bc18d2..ac963a6 100644
--- a/gcc/rust/expand/rust-derive-partial-eq.h
+++ b/gcc/rust/expand/rust-derive-partial-eq.h
@@ -30,12 +30,16 @@ class DerivePartialEq : DeriveVisitor
 public:
   DerivePartialEq (location_t loc);
 
-  std::unique_ptr<AST::Item> go (Item &item);
+  std::vector<std::unique_ptr<AST::Item>> go (Item &item);
 
 private:
-  std::unique_ptr<Item> expanded;
+  std::vector<std::unique_ptr<Item>> expanded;
 
-  std::unique_ptr<Item> partial_eq_impl (
+  /**
+   * Generate both an implementation of `PartialEq` and `StructuralPartialEq`
+   * for the given type
+   */
+  std::vector<std::unique_ptr<Item>> partialeq_impls (
     std::unique_ptr<AssociatedItem> &&eq_fn, std::string name,
     const std::vector<std::unique_ptr<GenericParam>> &type_generics);
 
diff --git a/gcc/rust/expand/rust-derive.cc b/gcc/rust/expand/rust-derive.cc
index bfcfd8f..56e0e94 100644
--- a/gcc/rust/expand/rust-derive.cc
+++ b/gcc/rust/expand/rust-derive.cc
@@ -52,7 +52,7 @@ DeriveVisitor::derive (Item &item, const Attribute &attr,
     case BuiltinMacro::Eq:
       return vec (DeriveEq (attr.get_locus ()).go (item));
     case BuiltinMacro::PartialEq:
-      return vec (DerivePartialEq (attr.get_locus ()).go (item));
+      return DerivePartialEq (attr.get_locus ()).go (item);
     case BuiltinMacro::Ord:
     case BuiltinMacro::PartialOrd:
     case BuiltinMacro::Hash:
diff --git a/gcc/testsuite/rust/compile/derive-eq-invalid.rs b/gcc/testsuite/rust/compile/derive-eq-invalid.rs
index 0c4d48e..b0bf856 100644
--- a/gcc/testsuite/rust/compile/derive-eq-invalid.rs
+++ b/gcc/testsuite/rust/compile/derive-eq-invalid.rs
@@ -21,6 +21,12 @@ struct PhantomData<T>;
 #[lang = "sized"]
 trait Sized {}
 
+#[lang = "structural_peq"]
+trait StructuralPartialEq {}
+
+#[lang = "structural_teq"]
+trait StructuralEq {}
+
 #[derive(PartialEq)]
 struct NotEq;
 
diff --git a/gcc/testsuite/rust/compile/derive-partialeq1.rs b/gcc/testsuite/rust/compile/derive-partialeq1.rs
index 7151324..35e33fb 100644
--- a/gcc/testsuite/rust/compile/derive-partialeq1.rs
+++ b/gcc/testsuite/rust/compile/derive-partialeq1.rs
@@ -6,6 +6,9 @@ trait Sized {}
 #[lang = "copy"]
 trait Copy {}
 
+#[lang = "structural_peq"]
+trait StructuralPartialEq {}
+
 #[lang = "eq"]
 pub trait PartialEq<Rhs: ?Sized = Self> {
     /// This method tests for `self` and `other` values to be equal, and is used
diff --git a/gcc/testsuite/rust/execute/torture/derive-partialeq1.rs b/gcc/testsuite/rust/execute/torture/derive-partialeq1.rs
index 4d5124e..67b2773 100644
--- a/gcc/testsuite/rust/execute/torture/derive-partialeq1.rs
+++ b/gcc/testsuite/rust/execute/torture/derive-partialeq1.rs
@@ -25,6 +25,9 @@ pub trait PartialEq<Rhs: ?Sized = Self> {
     }
 }
 
+#[lang = "structural_peq"]
+trait StructuralPartialEq {}
+
 #[derive(PartialEq, Copy)] // { dg-warning "unused name" }
 struct Foo;