[binutils-gdb] gdb/python: allow ref_ptr<T, Policy>::new_reference to accept subclasses of T

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=f0cfbf6ceda8396291d736858cfd713cc4a0e0da

commit f0cfbf6ceda8396291d736858cfd713cc4a0e0da
Author: Matthieu Longo <[email protected]>
Date:   Thu Feb 26 17:20:20 2026 +0000

    gdb/python: allow ref_ptr<T, Policy>::new_reference to accept subclasses of T
    
    When ref_ptr<T,Policy>::new_reference() is specialized for 'PyObject'
    (i.e. gdbpy_ref<>), it currently requires the argument type to be exactly
    'PyObject *'. As a result, pointers to subclasses of 'PyObject' must be
    explicitly cast before being passed, making call sites unnecessarily
    verbose.
    
    This patch makes ref_ptr<T,Policy>::new_reference() a template method
    that accepts both T and subclasses of T, performing the cast to 'T *'
    internally when needed. This removes redundant casts at call sites
    without changing behavior.
    
    Approved-By: Tom Tromey <[email protected]>

Diff:
---
 gdb/python/py-block.c    | 2 +-
 gdb/python/py-inferior.c | 2 +-
 gdbsupport/gdb_ref_ptr.h | 5 ++++-
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/gdb/python/py-block.c b/gdb/python/py-block.c
index 263819e1292..4d77242ca0d 100644
--- a/gdb/python/py-block.c
+++ b/gdb/python/py-block.c
@@ -346,7 +346,7 @@ block_to_block_object (const struct block *block, struct objfile *objfile)
   block_object *result = (block_object *) htab_find_with_hash (table, block,
 							       hash);
   if (result != nullptr)
-    return gdbpy_ref<>::new_reference ((PyObject *) result);
+    return gdbpy_ref<>::new_reference (result);
 
   result = PyObject_New (block_object, &block_object_type);
   if (result == nullptr)
diff --git a/gdb/python/py-inferior.c b/gdb/python/py-inferior.c
index 76e3da9f620..ed28ccf3c07 100644
--- a/gdb/python/py-inferior.c
+++ b/gdb/python/py-inferior.c
@@ -400,7 +400,7 @@ infpy_threads (PyObject *self, PyObject *args)
 
   for (const thread_map_t::value_type &entry : *inf_obj->threads)
     {
-      auto thr = gdbpy_ref<>::new_reference ((PyObject *) entry.second.get ());
+      gdbpy_ref<> thr = entry.second;
       if (PyTuple_SetItem (tuple.get (), i++, thr.release ()) < 0)
 	return nullptr;
     }
diff --git a/gdbsupport/gdb_ref_ptr.h b/gdbsupport/gdb_ref_ptr.h
index 4352ab3e7c0..0eb654324c6 100644
--- a/gdbsupport/gdb_ref_ptr.h
+++ b/gdbsupport/gdb_ref_ptr.h
@@ -197,9 +197,12 @@ public:
   }
 
   /* Acquire a new reference and return a ref_ptr that owns it.  */
-  static ref_ptr<T, Policy> new_reference (T *obj)
+  template <class TObj>
+  static ref_ptr<T, Policy> new_reference (TObj *obj)
   {
     Policy::incref (obj);
+    if constexpr (std::is_base_of<T, TObj>::value)
+      return ref_ptr<T, Policy> (static_cast<T *> (obj));
     return ref_ptr<T, Policy> (obj);
   }