gccrs: format-args: Add base for expanding FormatArgs nodes

gcc/rust/ChangeLog:

	* Make-lang.in: Add new object.
	* hir/rust-ast-lower-expr.cc (ASTLoweringExpr::visit): Remove calls to
	FormatArgsLowering.
	* expand/rust-expand-format-args.cc: New file.
	* expand/rust-expand-format-args.h: New file.

4 files changed, 76 insertions, 4 deletions

diff --git a/gcc/rust/Make-lang.in b/gcc/rust/Make-lang.in
index f166b02..cbb9da0 100644
--- a/gcc/rust/Make-lang.in
+++ b/gcc/rust/Make-lang.in
@@ -205,6 +205,7 @@ GRS_OBJS = \
     rust/rust-unicode.o \
     rust/rust-punycode.o \
 	rust/rust-lang-item.o \
+	rust/rust-expand-format-args.o \
     $(END)
 # removed object files from here
 
diff --git a/gcc/rust/expand/rust-expand-format-args.cc b/gcc/rust/expand/rust-expand-format-args.cc
new file mode 100644
index 0000000..52249cb
--- /dev/null
+++ b/gcc/rust/expand/rust-expand-format-args.cc
@@ -0,0 +1,43 @@
+// Copyright (C) 2024 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-expand-format-args.h"
+#include "rust-builtin-ast-nodes.h"
+
+namespace Rust {
+
+tl::optional<AST::Fragment>
+expand_format_args (AST::FormatArgs &fmt)
+{
+  for (const auto &node : fmt.get_template ().get_pieces ())
+    {
+      switch (node.tag)
+	{
+	case Fmt::Piece::Tag::String:
+	  // rust_debug ("[ARTHUR]: %s", node.string._0.c_str ());
+
+	case Fmt::Piece::Tag::NextArgument:
+	  rust_debug ("[ARTHUR]: NextArgument");
+	  break;
+	}
+    }
+
+  return tl::nullopt;
+}
+
+} // namespace Rust
diff --git a/gcc/rust/expand/rust-expand-format-args.h b/gcc/rust/expand/rust-expand-format-args.h
new file mode 100644
index 0000000..1481f36
--- /dev/null
+++ b/gcc/rust/expand/rust-expand-format-args.h
@@ -0,0 +1,32 @@
+// Copyright (C) 2024 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_EXPAND_FORMAT_ARGS_H
+#define RUST_EXPAND_FORMAT_ARGS_H
+
+#include "optional.h"
+#include "rust-ast-fragment.h"
+
+namespace Rust {
+
+tl::optional<AST::Fragment>
+expand_format_args (AST::FormatArgs &fmt);
+
+} // namespace Rust
+
+#endif //! RUST_EXPAND_FORMAT_ARGS_H
diff --git a/gcc/rust/hir/rust-ast-lower-expr.cc b/gcc/rust/hir/rust-ast-lower-expr.cc
index 6944db9..c414643 100644
--- a/gcc/rust/hir/rust-ast-lower-expr.cc
+++ b/gcc/rust/hir/rust-ast-lower-expr.cc
@@ -19,7 +19,6 @@
 #include "rust-ast-lower-expr.h"
 #include "rust-ast-lower-base.h"
 #include "rust-ast-lower-block.h"
-#include "rust-ast-lower-format-args.h"
 #include "rust-ast-lower-struct-field-expr.h"
 #include "rust-ast-lower-pattern.h"
 #include "rust-ast-lower-type.h"
@@ -824,9 +823,6 @@ ASTLoweringExpr::visit (AST::ClosureExprInnerTyped &expr)
 void
 ASTLoweringExpr::visit (AST::FormatArgs &fmt)
 {
-  // Lowering FormatArgs is complex, and this file is already very long
-  translated = FormatArgsLowering ().go (fmt);
-
   rust_sorry_at (fmt.get_locus (),
 		 "FormatArgs lowering is not implemented yet");
 }