HIR Visitor refactoring

This change split the single HIR visitor in smaller abstract ones:
- Stmt
- VisItem
- Pattern
- ExternalItem
- Impl
- Type
- Expression

Instead of providing a Base class with empty visit() methods, they are kept
abstract to avoid the case where a missing visit() is silently ignored:
implementors must explicitely override all visit.

There is also a FullVisitor that covers all HIR nodes and also provides a Base
class with empty behavior.

fixes #825

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

1 files changed, 2 insertions, 3 deletions

diff --git a/gcc/rust/backend/rust-compile-extern.h b/gcc/rust/backend/rust-compile-extern.h
index 1412e7a..1987805 100644
--- a/gcc/rust/backend/rust-compile-extern.h
+++ b/gcc/rust/backend/rust-compile-extern.h
@@ -25,10 +25,9 @@
 namespace Rust {
 namespace Compile {
 
-class CompileExternItem : public HIRCompileBase
+class CompileExternItem : public HIRCompileBase,
+			  public HIR::HIRExternalItemVisitor
 {
-  using Rust::Compile::HIRCompileBase::visit;
-
 public:
   static void compile (HIR::ExternalItem *item, Context *ctx,
 		       TyTy::BaseType *concrete = nullptr)