ast: Add base nodes for FormatArgs

This commit adds a base for creating AST FormatArgs nodes after expanding
invocations of `format_args!()`. These nodes will then be expanded to
the proper runtime function calls (to core::fmt::rt) during the AST
lowering.

gcc/rust/ChangeLog:

	* ast/rust-builtin-ast-nodes.h: New file.
	* ast/rust-ast-full-decls.h (class FormatArgs): Declare new class.
	* ast/rust-ast-collector.cc: Handle FormatArgs nodes properly.
	* ast/rust-ast-collector.h: Likewise.
	* ast/rust-ast-full.h: Likewise.
	* ast/rust-ast-visitor.cc: Likewise.
	* ast/rust-ast-visitor.h: Likewise.
	* ast/rust-ast.cc: Likewise.
	* ast/rust-ast.h: Likewise.
	* expand/rust-derive.h: Likewise.
	* hir/rust-ast-lower-base.cc: Likewise.
	* hir/rust-ast-lower-base.h: Likewise.
	* hir/rust-ast-lower-expr.cc: Likewise.
	* hir/rust-ast-lower-expr.h: Likewise.
	* resolve/rust-ast-resolve-base.cc: Likewise.
	* resolve/rust-ast-resolve-base.h: Likewise.

2 files changed, 9 insertions, 0 deletions

diff --git a/gcc/rust/resolve/rust-ast-resolve-base.cc b/gcc/rust/resolve/rust-ast-resolve-base.cc
index c88bd58..04a0bb6 100644
--- a/gcc/rust/resolve/rust-ast-resolve-base.cc
+++ b/gcc/rust/resolve/rust-ast-resolve-base.cc
@@ -650,5 +650,11 @@ void
 ResolverBase::visit (AST::FunctionParam &)
 {}
 
+void
+ResolverBase::visit (AST::FormatArgs &fmt)
+{
+  rust_sorry_at (0, "unimplemented format_args!() visitor");
+}
+
 } // namespace Resolver
 } // namespace Rust
diff --git a/gcc/rust/resolve/rust-ast-resolve-base.h b/gcc/rust/resolve/rust-ast-resolve-base.h
index 9bc6433..3b4d286 100644
--- a/gcc/rust/resolve/rust-ast-resolve-base.h
+++ b/gcc/rust/resolve/rust-ast-resolve-base.h
@@ -20,6 +20,7 @@
 #define RUST_AST_RESOLVE_BASE_H
 
 #include "rust-ast-visitor.h"
+#include "rust-ast.h"
 #include "rust-name-resolver.h"
 #include "rust-diagnostics.h"
 #include "rust-location.h"
@@ -198,6 +199,8 @@ public:
   void visit (AST::VariadicParam &param);
   void visit (AST::SelfParam &param);
 
+  void visit (AST::FormatArgs &fmt);
+
 protected:
   ResolverBase ()
     : resolver (Resolver::get ()), mappings (Analysis::Mappings::get ()),