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, 22 insertions, 8 deletions

diff --git a/gcc/rust/backend/rust-compile-item.h b/gcc/rust/backend/rust-compile-item.h
index 897fe85..63316b9 100644
--- a/gcc/rust/backend/rust-compile-item.h
+++ b/gcc/rust/backend/rust-compile-item.h
@@ -24,11 +24,9 @@
 namespace Rust {
 namespace Compile {
 
-class CompileItem : public HIRCompileBase
+class CompileItem : public HIRCompileBase, public HIR::HIRStmtVisitor
 {
 protected:
-  using Rust::Compile::HIRCompileBase::visit;
-
 public:
   static tree compile (HIR::Item *item, Context *ctx,
 		       TyTy::BaseType *concrete = nullptr,
@@ -46,17 +44,33 @@ public:
   }
 
   void visit (HIR::StaticItem &var) override;
-
   void visit (HIR::ConstantItem &constant) override;
-
   void visit (HIR::Function &function) override;
-
   void visit (HIR::ImplBlock &impl_block) override;
-
   void visit (HIR::ExternBlock &extern_block) override;
-
   void visit (HIR::Module &module) override;
 
+  // Empty visit for unused Stmt HIR nodes.
+  void visit (HIR::TupleStruct &) override {}
+  void visit (HIR::EnumItem &) override {}
+  void visit (HIR::EnumItemTuple &) override {}
+  void visit (HIR::EnumItemStruct &) override {}
+  void visit (HIR::EnumItemDiscriminant &) override {}
+  void visit (HIR::TypePathSegmentFunction &) override {}
+  void visit (HIR::TypePath &) override {}
+  void visit (HIR::QualifiedPathInType &) override {}
+  void visit (HIR::ExternCrate &) override {}
+  void visit (HIR::UseDeclaration &) override {}
+  void visit (HIR::TypeAlias &) override {}
+  void visit (HIR::StructStruct &) override {}
+  void visit (HIR::Enum &) override {}
+  void visit (HIR::Union &) override {}
+  void visit (HIR::Trait &) override {}
+  void visit (HIR::EmptyStmt &) override {}
+  void visit (HIR::LetStmt &) override {}
+  void visit (HIR::ExprStmtWithoutBlock &) override {}
+  void visit (HIR::ExprStmtWithBlock &) override {}
+
 protected:
   CompileItem (Context *ctx, TyTy::BaseType *concrete, Location ref_locus)
     : HIRCompileBase (ctx), concrete (concrete), reference (error_mark_node),