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, 25 insertions, 3 deletions

diff --git a/gcc/rust/backend/rust-compile-stmt.h b/gcc/rust/backend/rust-compile-stmt.h
index 24a2084..2dfb520 100644
--- a/gcc/rust/backend/rust-compile-stmt.h
+++ b/gcc/rust/backend/rust-compile-stmt.h
@@ -26,10 +26,8 @@
 namespace Rust {
 namespace Compile {
 
-class CompileStmt : public HIRCompileBase
+class CompileStmt : public HIRCompileBase, public HIR::HIRStmtVisitor
 {
-  using Rust::Compile::HIRCompileBase::visit;
-
 public:
   static tree Compile (HIR::Stmt *stmt, Context *ctx)
   {
@@ -103,6 +101,30 @@ public:
       }
   }
 
+  // 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::Module &) override {}
+  void visit (HIR::ExternCrate &) override {}
+  void visit (HIR::UseDeclaration &) override {}
+  void visit (HIR::Function &) override {}
+  void visit (HIR::TypeAlias &) override {}
+  void visit (HIR::StructStruct &) override {}
+  void visit (HIR::Enum &) override {}
+  void visit (HIR::Union &) override {}
+  void visit (HIR::ConstantItem &) override {}
+  void visit (HIR::StaticItem &) override {}
+  void visit (HIR::Trait &) override {}
+  void visit (HIR::ImplBlock &) override {}
+  void visit (HIR::ExternBlock &) override {}
+  void visit (HIR::EmptyStmt &) override {}
+
 private:
   CompileStmt (Context *ctx) : HIRCompileBase (ctx), translated (nullptr) {}