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, 26 insertions, 11 deletions

diff --git a/gcc/rust/backend/rust-compile-pattern.h b/gcc/rust/backend/rust-compile-pattern.h
index 535cf36..36e4ef3 100644
--- a/gcc/rust/backend/rust-compile-pattern.h
+++ b/gcc/rust/backend/rust-compile-pattern.h
@@ -21,10 +21,9 @@
 namespace Rust {
 namespace Compile {
 
-class CompilePatternCaseLabelExpr : public HIRCompileBase
+class CompilePatternCaseLabelExpr : public HIRCompileBase,
+				    public HIR::HIRPatternVisitor
 {
-  using Rust::Compile::HIRCompileBase::visit;
-
 public:
   static tree Compile (HIR::Pattern *pattern, tree associated_case_label,
 		       Context *ctx)
@@ -35,14 +34,20 @@ public:
   }
 
   void visit (HIR::PathInExpression &pattern) override;
-
   void visit (HIR::StructPattern &pattern) override;
-
   void visit (HIR::TupleStructPattern &pattern) override;
-
   void visit (HIR::WildcardPattern &pattern) override;
 
-private:
+  // Empty visit for unused Pattern HIR nodes.
+  void visit (HIR::GroupedPattern &) override {}
+  void visit (HIR::IdentifierPattern &) override {}
+  void visit (HIR::LiteralPattern &) override {}
+  void visit (HIR::QualifiedPathInExpression &) override {}
+  void visit (HIR::RangePattern &) override {}
+  void visit (HIR::ReferencePattern &) override {}
+  void visit (HIR::SlicePattern &) override {}
+  void visit (HIR::TuplePattern &) override {}
+
   CompilePatternCaseLabelExpr (Context *ctx, tree associated_case_label)
     : HIRCompileBase (ctx), case_label_expr (error_mark_node),
       associated_case_label (associated_case_label)
@@ -52,10 +57,9 @@ private:
   tree associated_case_label;
 };
 
-class CompilePatternBindings : public HIRCompileBase
+class CompilePatternBindings : public HIRCompileBase,
+			       public HIR::HIRPatternVisitor
 {
-  using Rust::Compile::HIRCompileBase::visit;
-
 public:
   static void Compile (HIR::Pattern *pattern, tree match_scrutinee_expr,
 		       Context *ctx)
@@ -65,9 +69,20 @@ public:
   }
 
   void visit (HIR::StructPattern &pattern) override;
-
   void visit (HIR::TupleStructPattern &pattern) override;
 
+  // Empty visit for unused Pattern HIR nodes.
+  void visit (HIR::GroupedPattern &) override {}
+  void visit (HIR::IdentifierPattern &) override {}
+  void visit (HIR::LiteralPattern &) override {}
+  void visit (HIR::PathInExpression &) override {}
+  void visit (HIR::QualifiedPathInExpression &) override {}
+  void visit (HIR::RangePattern &) override {}
+  void visit (HIR::ReferencePattern &) override {}
+  void visit (HIR::SlicePattern &) override {}
+  void visit (HIR::TuplePattern &) override {}
+  void visit (HIR::WildcardPattern &) override {}
+
 private:
   CompilePatternBindings (Context *ctx, tree match_scrutinee_expr)
     : HIRCompileBase (ctx), match_scrutinee_expr (match_scrutinee_expr)