[gcc/devel/rust/master] ast: visitor pattern -> overload syntax compatibility layer

[Thomas Schwinge <tschwinge@gcc.gnu.org>]

https://gcc.gnu.org/g:56a227a63b3843fd5eadc093079b833fe1f93ef9

commit 56a227a63b3843fd5eadc093079b833fe1f93ef9
Author: Jakub Dupak <dev@jakubdupak.com>
Date:   Thu Oct 27 22:27:55 2022 +0200

    ast: visitor pattern -> overload syntax compatibility layer
    
    Signed-off-by: Jakub Dupak <dev@jakubdupak.com>

Diff:
---
 gcc/rust/ast/rust-ast-dump.cc | 7 +++++++
 gcc/rust/ast/rust-ast-dump.h  | 8 ++++++++
 2 files changed, 15 insertions(+)

diff --git a/gcc/rust/ast/rust-ast-dump.cc b/gcc/rust/ast/rust-ast-dump.cc
index 4817962f767..9771f432ea0 100644
--- a/gcc/rust/ast/rust-ast-dump.cc
+++ b/gcc/rust/ast/rust-ast-dump.cc
@@ -62,6 +62,13 @@ Dump::go (AST::Item &item)
   item.accept_vis (*this);
 }
 
+template <typename T>
+void
+Dump::visit (std::unique_ptr<T> &node)
+{
+  node->accept_vis (*this);
+}
+
 void
 Dump::format_function_param (FunctionParam &param)
 {
diff --git a/gcc/rust/ast/rust-ast-dump.h b/gcc/rust/ast/rust-ast-dump.h
index 9fe8ee95493..7cd922e0ac9 100644
--- a/gcc/rust/ast/rust-ast-dump.h
+++ b/gcc/rust/ast/rust-ast-dump.h
@@ -72,6 +72,14 @@ private:
   std::ostream &stream;
   Indent indentation;
 
+  /**
+   * Compatibility layer for using the visitor pattern on polymorphic classes
+   * with a unified overload syntax. This allows us to call `visit` both on
+   * types implementing `accept_vis` method and for classes for which the
+   * `visit` method is directly implemented.
+   */
+  template <typename T> void visit (std::unique_ptr<T> &node);
+
   /**
    * Format together common items of functions: Parameters, return type, block
    */