[gcc r17-3104] gccrs: rust: Add const getter overloads for HIR pattern fields

https://gcc.gnu.org/g:6614915cf4cca6d875a018587096af4519b548ac

commit r17-3104-g6614915cf4cca6d875a018587096af4519b548ac
Author: Egas Ribeiro <[email protected]>
Date:   Tue May 19 17:52:48 2026 +0100

    gccrs: rust: Add const getter overloads for HIR pattern fields
    
    These const overloads are needed by the type-aware refutability check in
    HIR pattern nodes, which accesses pattern fields through const
    references.
    
            Addresses: Rust-GCC#2082
    
    gcc/rust/ChangeLog:
    
            * hir/tree/rust-hir-pattern.h: Add const overloads.
    
    Co-authored-by: João Novo <[email protected]>
    Signed-off-by: Egas Ribeiro <[email protected]>

Diff:
---
 gcc/rust/hir/tree/rust-hir-pattern.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/gcc/rust/hir/tree/rust-hir-pattern.h b/gcc/rust/hir/tree/rust-hir-pattern.h
index c5997c11d6f9..bc9c63fae0a1 100644
--- a/gcc/rust/hir/tree/rust-hir-pattern.h
+++ b/gcc/rust/hir/tree/rust-hir-pattern.h
@@ -586,8 +586,13 @@ public:
   void accept_vis (HIRFullVisitor &vis) override;
 
   TupleIndex get_index () { return index; }
+
+  TupleIndex get_index () const { return index; }
+
   Pattern &get_tuple_pattern () { return *tuple_pattern; }
 
+  const Pattern &get_tuple_pattern () const { return *tuple_pattern; }
+
   ItemType get_item_type () const override final { return ItemType::TUPLE_PAT; }
 
 protected:
@@ -645,6 +650,7 @@ public:
   Identifier get_identifier () const { return ident; }
 
   Pattern &get_pattern () { return *ident_pattern; }
+  Pattern &get_pattern () const { return *ident_pattern; }
 
 protected:
   /* Use covariance to implement clone function as returning this object rather
@@ -754,6 +760,12 @@ public:
   {
     return fields;
   }
+
+  const std::vector<std::unique_ptr<StructPatternField>> &
+  get_struct_pattern_fields () const
+  {
+    return fields;
+  }
 };
 
 // Struct pattern HIR node representation