From 9cdaff9f5aa4174bad954df3b186865e3b73918b Mon Sep 17 00:00:00 2001
From: Philip Herron <philip.herron@embecosm.com>
Date: Wed, 20 Oct 2021 16:13:16 +0100
Subject: [PATCH] Constify GetUsedSubstArgs

This mapper class does not need mutability and can easily be made const
enforcing ownership.
---
 gcc/rust/typecheck/rust-substitution-mapper.h | 50 +++++++++----------
 gcc/rust/typecheck/rust-tyty.h                |  2 +-
 2 files changed, 26 insertions(+), 26 deletions(-)

diff --git a/gcc/rust/typecheck/rust-substitution-mapper.h b/gcc/rust/typecheck/rust-substitution-mapper.h
index a6e7e8080c26..b7c23fb19c3d 100644
--- a/gcc/rust/typecheck/rust-substitution-mapper.h
+++ b/gcc/rust/typecheck/rust-substitution-mapper.h
@@ -317,51 +317,51 @@ private:
   TyTy::BaseType *resolved;
 };
 
-class GetUsedSubstArgs : public TyTy::TyVisitor
+class GetUsedSubstArgs : public TyTy::TyConstVisitor
 {
 public:
-  static TyTy::SubstitutionArgumentMappings From (TyTy::BaseType *from)
+  static TyTy::SubstitutionArgumentMappings From (const TyTy::BaseType *from)
   {
     GetUsedSubstArgs mapper;
     from->accept_vis (mapper);
     return mapper.args;
   }
 
-  void visit (TyTy::FnType &type) override
+  void visit (const TyTy::FnType &type) override
   {
     args = type.get_substitution_arguments ();
   }
 
-  void visit (TyTy::ADTType &type) override
+  void visit (const TyTy::ADTType &type) override
   {
     args = type.get_substitution_arguments ();
   }
 
-  void visit (TyTy::ClosureType &type) override
+  void visit (const TyTy::ClosureType &type) override
   {
     args = type.get_substitution_arguments ();
   }
 
-  void visit (TyTy::InferType &) override {}
-  void visit (TyTy::TupleType &) override {}
-  void visit (TyTy::FnPtr &) override {}
-  void visit (TyTy::ArrayType &) override {}
-  void visit (TyTy::BoolType &) override {}
-  void visit (TyTy::IntType &) override {}
-  void visit (TyTy::UintType &) override {}
-  void visit (TyTy::FloatType &) override {}
-  void visit (TyTy::USizeType &) override {}
-  void visit (TyTy::ISizeType &) override {}
-  void visit (TyTy::ErrorType &) override {}
-  void visit (TyTy::CharType &) override {}
-  void visit (TyTy::ReferenceType &) override {}
-  void visit (TyTy::PointerType &) override {}
-  void visit (TyTy::ParamType &) override {}
-  void visit (TyTy::StrType &) override {}
-  void visit (TyTy::NeverType &) override {}
-  void visit (TyTy::PlaceholderType &) override {}
-  void visit (TyTy::ProjectionType &) override {}
-  void visit (TyTy::DynamicObjectType &) override {}
+  void visit (const TyTy::InferType &) override {}
+  void visit (const TyTy::TupleType &) override {}
+  void visit (const TyTy::FnPtr &) override {}
+  void visit (const TyTy::ArrayType &) override {}
+  void visit (const TyTy::BoolType &) override {}
+  void visit (const TyTy::IntType &) override {}
+  void visit (const TyTy::UintType &) override {}
+  void visit (const TyTy::FloatType &) override {}
+  void visit (const TyTy::USizeType &) override {}
+  void visit (const TyTy::ISizeType &) override {}
+  void visit (const TyTy::ErrorType &) override {}
+  void visit (const TyTy::CharType &) override {}
+  void visit (const TyTy::ReferenceType &) override {}
+  void visit (const TyTy::PointerType &) override {}
+  void visit (const TyTy::ParamType &) override {}
+  void visit (const TyTy::StrType &) override {}
+  void visit (const TyTy::NeverType &) override {}
+  void visit (const TyTy::PlaceholderType &) override {}
+  void visit (const TyTy::ProjectionType &) override {}
+  void visit (const TyTy::DynamicObjectType &) override {}
 
 private:
   GetUsedSubstArgs () : args (TyTy::SubstitutionArgumentMappings::error ()) {}
diff --git a/gcc/rust/typecheck/rust-tyty.h b/gcc/rust/typecheck/rust-tyty.h
index 03e3296c6b54..7cd99f24d3d9 100644
--- a/gcc/rust/typecheck/rust-tyty.h
+++ b/gcc/rust/typecheck/rust-tyty.h
@@ -884,7 +884,7 @@ public:
 
   bool was_substituted () const { return !needs_substitution (); }
 
-  SubstitutionArgumentMappings get_substitution_arguments ()
+  SubstitutionArgumentMappings get_substitution_arguments () const
   {
     return used_arguments;
   }
-- 
2.43.5