From: Arthur Cohen <arthur.co...@embecosm.com>
gcc/rust/ChangeLog:
* expand/rust-derive-debug.cc: New file.
* expand/rust-derive-debug.h: New file.
* Make-lang.in: Compile them.
* expand/rust-derive.cc (DeriveVisitor::derive): Call into DeriveDebug.
gcc/testsuite/ChangeLog:
* rust/compile/derive-debug1.rs: New test.
* rust/compile/nr2/exclude: Exclude it.
---
gcc/rust/Make-lang.in | 1 +
gcc/rust/expand/rust-derive-debug.cc | 130 ++++++++++++++++++++
gcc/rust/expand/rust-derive-debug.h | 55 +++++++++
gcc/rust/expand/rust-derive.cc | 6 +
gcc/testsuite/rust/compile/derive-debug1.rs | 41 ++++++
gcc/testsuite/rust/compile/nr2/exclude | 1 +
6 files changed, 234 insertions(+)
create mode 100644 gcc/rust/expand/rust-derive-debug.cc
create mode 100644 gcc/rust/expand/rust-derive-debug.h
create mode 100644 gcc/testsuite/rust/compile/derive-debug1.rs
diff --git a/gcc/rust/Make-lang.in b/gcc/rust/Make-lang.in
index f317c678359..bc58a341131 100644
--- a/gcc/rust/Make-lang.in
+++ b/gcc/rust/Make-lang.in
@@ -96,6 +96,7 @@ GRS_OBJS = \
rust/rust-derive.o \
rust/rust-derive-clone.o \
rust/rust-derive-copy.o \
+ rust/rust-derive-debug.o \
rust/rust-proc-macro.o \
rust/rust-macro-invoc-lexer.o \
rust/rust-proc-macro-invoc-lexer.o \
diff --git a/gcc/rust/expand/rust-derive-debug.cc
b/gcc/rust/expand/rust-derive-debug.cc
new file mode 100644
index 00000000000..910f27c67b2
--- /dev/null
+++ b/gcc/rust/expand/rust-derive-debug.cc
@@ -0,0 +1,130 @@
+// Copyright (C) 2025 Free Software Foundation, Inc.
+
+// This file is part of GCC.
+
+// GCC is free software; you can redistribute it and/or modify it under
+// the terms of the GNU General Public License as published by the Free
+// Software Foundation; either version 3, or (at your option) any later
+// version.
+
+// GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+// WARRANTY; without even the implied warranty of MERCHANTABILITY or
+// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+// for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with GCC; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+#include "rust-derive-debug.h"
+#include "rust-ast.h"
+#include "rust-hir-map.h"
+#include "rust-system.h"
+
+namespace Rust {
+namespace AST {
+
+DeriveDebug::DeriveDebug (location_t loc)
+ : DeriveVisitor (loc), expanded (nullptr)
+{}
+
+std::unique_ptr<Item>
+DeriveDebug::go (Item &item)
+{
+ item.accept_vis (*this);
+
+ rust_assert (expanded);
+
+ return std::move (expanded);
+}
+
+/* Pointer-ify something */
+template <typename T>
+static std::unique_ptr<T>
+ptrify (T value)
+{
+ return std::unique_ptr<T> (new T (value));
+}
+
+std::unique_ptr<AssociatedItem>
+DeriveDebug::stub_debug_fn ()
+{
+ auto unit_expr = builder.tuple ();
+ auto ok_expr
+ = ptrify (builder.path_in_expression (LangItem::Kind::RESULT_OK));
+
+ auto stub_return = builder.call (std::move (ok_expr), std::move (unit_expr));
+
+ // we can't use builder.block() here as it returns a unique_ptr<Expr> and
+ // Function's constructor expects a unique_ptr<BlockExpr>
+ auto block = std::unique_ptr<BlockExpr> (
+ new BlockExpr ({}, std::move (stub_return), {}, {},
+ AST::LoopLabel::error (), loc, loc));
+
+ auto self = builder.self_ref_param ();
+
+ auto return_type
+ = ptrify (builder.type_path ({"core", "fmt", "Result"}, true));
+
+ auto mut_fmt_type_inner
+ = ptrify (builder.type_path ({"core", "fmt", "Formatter"}, true));
+
+ auto mut_fmt_type
+ = builder.reference_type (std::move (mut_fmt_type_inner), true);
+
+ auto fmt = builder.function_param (builder.identifier_pattern ("_fmt"),
+ std::move (mut_fmt_type));
+
+ auto params = vec (std::move (self), std::move (fmt));
+
+ auto function = builder.function ({"fmt"}, std::move (params),
+ std::move (return_type), std::move (block));
+
+ return ptrify (function);
+}
+
+std::unique_ptr<Item>
+DeriveDebug::stub_derive_impl (
+ std::string name,
+ const std::vector<std::unique_ptr<GenericParam>> &type_generics)
+{
+ auto trait_items = vec (stub_debug_fn ());
+
+ auto debug = builder.type_path ({"core", "fmt", "Debug"}, true);
+ auto generics
+ = setup_impl_generics (name, type_generics, builder.trait_bound (debug));
+
+ return builder.trait_impl (debug, std::move (generics.self_type),
+ std::move (trait_items),
+ std::move (generics.impl));
+}
+
+void
+DeriveDebug::visit_struct (StructStruct &struct_item)
+{
+ expanded = stub_derive_impl (struct_item.get_identifier ().as_string (),
+ struct_item.get_generic_params ());
+}
+
+void
+DeriveDebug::visit_tuple (TupleStruct &tuple_item)
+{
+ expanded = stub_derive_impl (tuple_item.get_identifier ().as_string (),
+ tuple_item.get_generic_params ());
+}
+
+void
+DeriveDebug::visit_enum (Enum &enum_item)
+{
+ expanded = stub_derive_impl (enum_item.get_identifier ().as_string (),
+ enum_item.get_generic_params ());
+}
+
+void
+DeriveDebug::visit_union (Union &enum_item)
+{
+ rust_error_at (loc, "derive(Debug) cannot be derived for unions");
+}
+
+} // namespace AST
+} // namespace Rust
diff --git a/gcc/rust/expand/rust-derive-debug.h
b/gcc/rust/expand/rust-derive-debug.h
new file mode 100644
index 00000000000..14af89e551c
--- /dev/null
+++ b/gcc/rust/expand/rust-derive-debug.h
@@ -0,0 +1,55 @@
+// Copyright (C) 2025 Free Software Foundation, Inc.
+
+// This file is part of GCC.
+
+// GCC is free software; you can redistribute it and/or modify it under
+// the terms of the GNU General Public License as published by the Free
+// Software Foundation; either version 3, or (at your option) any later
+// version.
+
+// GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+// WARRANTY; without even the implied warranty of MERCHANTABILITY or
+// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+// for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with GCC; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+#ifndef RUST_DERIVE_DEBUG_H
+#define RUST_DERIVE_DEBUG_H
+
+#include "rust-derive.h"
+#include "rust-ast.h"
+
+namespace Rust {
+namespace AST {
+
+// This derive is currently incomplete and only generate a stub implementation
+// which does not do any debug formatting
+class DeriveDebug : DeriveVisitor
+{
+public:
+ DeriveDebug (location_t loc);
+
+ std::unique_ptr<Item> go (Item &);
+
+private:
+ std::unique_ptr<Item> expanded;
+
+ std::unique_ptr<AssociatedItem> stub_debug_fn ();
+
+ std::unique_ptr<Item> stub_derive_impl (
+ std::string name,
+ const std::vector<std::unique_ptr<GenericParam>> &type_generics);
+
+ virtual void visit_struct (StructStruct &struct_item) override;
+ virtual void visit_tuple (TupleStruct &tuple_item) override;
+ virtual void visit_enum (Enum &enum_item) override;
+ virtual void visit_union (Union &enum_item) override;
+};
+
+} // namespace AST
+} // namespace Rust
+
+#endif // ! RUST_DERIVE_DEBUG_H
diff --git a/gcc/rust/expand/rust-derive.cc b/gcc/rust/expand/rust-derive.cc
index 13675ba594c..2c5ccc3ce52 100644
--- a/gcc/rust/expand/rust-derive.cc
+++ b/gcc/rust/expand/rust-derive.cc
@@ -19,6 +19,7 @@
#include "rust-derive.h"
#include "rust-derive-clone.h"
#include "rust-derive-copy.h"
+#include "rust-derive-debug.h"
namespace Rust {
namespace AST {
@@ -38,6 +39,11 @@ DeriveVisitor::derive (Item &item, const Attribute &attr,
case BuiltinMacro::Copy:
return DeriveCopy (attr.get_locus ()).go (item);
case BuiltinMacro::Debug:
+ rust_warning_at (
+ attr.get_locus (), 0,
+ "derive(Debug) is not fully implemented yet and has no effect - only a "
+ "stub implementation will be generated");
+ return DeriveDebug (attr.get_locus ()).go (item);
case BuiltinMacro::Default:
case BuiltinMacro::Eq:
case BuiltinMacro::PartialEq:
diff --git a/gcc/testsuite/rust/compile/derive-debug1.rs
b/gcc/testsuite/rust/compile/derive-debug1.rs
new file mode 100644
index 00000000000..2596a3792f1
--- /dev/null
+++ b/gcc/testsuite/rust/compile/derive-debug1.rs
@@ -0,0 +1,41 @@
+#[lang = "sized"]
+trait Sized {}
+
+mod core {
+ pub mod result {
+ pub enum Result<T, E> {
+ #[lang = "Ok"]
+ Ok(T),
+ #[lang = "Err"]
+ Err(E),
+ }
+ }
+
+ mod fmt {
+ struct Formatter; // { dg-warning "is never constructed" }
+ struct Error; // { dg-warning "is never constructed" }
+
+ type Result = core::result::Result<(), Error>;
+
+ trait Debug {
+ fn fmt(&self, fmt: &mut Formatter) -> Result;
+ }
+ }
+}
+
+#[derive(Debug)] // { dg-warning "unused name" }
+// { dg-warning "stub implementation" "" { target *-*-* } .-1 }
+struct Foo { a: i32, b: i64 } // { dg-warning "is never constructed" }
+
+#[derive(Debug)] // { dg-warning "unused name" }
+// { dg-warning "stub implementation" "" { target *-*-* } .-1 }
+struct Bar(i32, i32); // { dg-warning "is never constructed" }
+
+#[derive(Debug)] // { dg-warning "unused name" }
+// { dg-warning "stub implementation" "" { target *-*-* } .-1 }
+enum Baz {
+ A,
+ B(i32),
+ C { a: i32 }
+}
+
diff --git a/gcc/testsuite/rust/compile/nr2/exclude
b/gcc/testsuite/rust/compile/nr2/exclude
index e5e5c12a978..acb4334e867 100644
--- a/gcc/testsuite/rust/compile/nr2/exclude
+++ b/gcc/testsuite/rust/compile/nr2/exclude
@@ -151,4 +151,5 @@ issue-3030.rs
traits12.rs
try-trait.rs
issue-3174.rs
+derive-debug1.rs
# please don't delete the trailing newline
--
2.45.2
