gccrs: Introduce AST::Visitable class for AST

AST::Visitable is an abstract class with a unique accept_vis() method.
Make all abstract AST node class inherit from this class.

Allows for easy definition of operations on nodes that must accept a
visitor.

The static Dump::dump() is an example of such use: the static method
accepts any AST node, creates a Dump visitor and have it visit the AST
starting at the node.

This change also inserts a debug(Visitable&) function in the global
namespace to make it easy to call from the debugger (similar to
debug_tree or debug(rtx*) functions).

gcc/rust/ChangeLog:

	* ast/rust-ast-dump.cc (Dump::debug): New.
	* ast/rust-ast-dump.h (Dump::debug): Untemplate it.
	(debug): New.
	* ast/rust-ast.h (class Visitable): New.
	(class TokenTree): Inherit from Visitable.
	(class MacroMatch): Likewise.
	(class AttrInput): Likewise.
	(class MetaItemInner): Likewise.
	(class Pattern): Likewise.
	(classTypeParamBound): Likewise.
	(class GenericParam): Likewise.
	(class TraitItem): Likewise.
	(classInherentImplItem): Likewise.
	(class TraitImplItem): Likewise.
	(class ExternalItem): Likewise.
	(class SingleASTNode): Likewise.

Signed-off-by: Marc Poulhiès <dkm@kataplop.net>

1 files changed, 6 insertions, 15 deletions

diff --git a/gcc/rust/ast/rust-ast-dump.h b/gcc/rust/ast/rust-ast-dump.h
index 4128733..26f7208 100644
--- a/gcc/rust/ast/rust-ast-dump.h
+++ b/gcc/rust/ast/rust-ast-dump.h
@@ -38,21 +38,8 @@ public:
   void go (AST::Crate &crate);
   void go (AST::Item &item);
 
-  /**
-   * Use the AST Dump as a debugging tool
-   */
-  template <typename T> static void debug (T &instance)
-  {
-    auto dump = Dump (std::cerr);
-
-    std::cerr << '\n';
-    instance.accept_vis (dump);
-    std::cerr << '\n';
-  }
-  template <typename T> static void debug (std::unique_ptr<T> &instance)
-  {
-    debug (*instance);
-  }
+  // Helper method to get a quick debug dump to standard error output
+  static void debug (Visitable &v);
 
 private:
   std::ostream &stream;
@@ -309,4 +296,8 @@ private:
 } // namespace AST
 } // namespace Rust
 
+// In the global namespace to make it easier to call from debugger
+void
+debug (Rust::AST::Visitable &v);
+
 #endif // !RUST_AST_DUMP_H