C++ify xmethod_worker, get rid of VEC(xmethod_worker_ptr)

The initial goal of this patch was to remove the usage of
VEC(xmethod_worker_ptr) and corresponding cleanups.  I ended up having
to  C++ify the xmethod_worker code, to be able to have xmethod_workers
free their data in destructors, and therefore be able to use vectors of
xmethod_worker unique_ptr.

The operations in extension_language_ops that act on one instance of
xmethod_worker (get result type, get args type, invoke) are transformed
to methods of xmethod_worker.  xmethod_worker becomes an abstract base
class with virtual pure methods which python_xmethod_worker implements.
The only xmethod-related operation left in extension_language_ops is
get_matching_xmethod_workers, which returns a list of xmethod_workers.

The changes are relatively straightforward, but here are some notes on
things that may raise eyebrows:

  - I was not really comfortable with the value_of_xmethod function.  At
  first it looks like a simple getter, so I considered making it a
  method of xmethod_worker.  But actually it creates a value and
  transfers the ownership of the xmethod_worker to it.  It would be a
  bit weird and error-prone if calling a method on an object silently
  removed the ownership of the object from the caller.  To reflect the
  behavior more accurately, I renamed it to value_from_xmethod and made
  it accept an rvalue-reference (so the caller knows it gives away the
  ownership).  I noticed the backlink from xmethod_worker to its owning
  value was not used, so I removed it.

  - Some code, like get_matching_xmethod_workers, made each callee fill
  a new vector, which was then merged in the result vector.  I think
  it's safe if we always pass the same vector around, and each
  implementation just appends to it.

  - The clone operation does not seem particularly useful, it is removed
  in the following patch.

gdb/ChangeLog:

	* extension-priv.h (enum ext_lang_rc): Remove, move to extension.h.
	(struct extension_language_ops) <clone_xmethod_worker_data>: Remove.
	<free_xmethod_worker_data>: Remove.
	<get_matching_xmethod_workers>: Chance VEC to std::vector.
	<get_xmethod_arg_types>: Remove.
	<get_xmethod_result_type>: Remove.
	<invoke_xmethod>: Remove.
	* extension.c (new_xmethod_worker): Remove.
	(clone_xmethod_worker): Remove.
	(get_matching_xmethod_workers): Return void, pass std::vector by
	pointer.
	(get_xmethod_arg_types): Rename to...
	(xmethod_worker::get_arg_types): ... this, and adjust.
	(get_xmethod_result_type): Rename to...
	(xmethod_worker::get_result_type): ... this, and adjust.
	(invoke_xmethod): Remove.
	(free_xmethod_worker): Remove.
	(free_xmethod_worker_vec): Remove.
	* extension.h (enum ext_lang_rc): Move here from
	extension-priv.h.
	(struct xmethod_worker): Add constructor and destructor.
	<data>: Remove.
	<value>: Remove.
	<invoke, clone, do_get_result_type, do_get_arg_types>: New
	virtual pure methods.
	<get_arg_types, get_result_type>: New methods.
	(xmethod_worker_ptr): Remove typedef.
	(DEF_VEC_P (xmethod_worker_ptr)): Remove.
	(xmethod_worker_vec): Remove typedef.
	(xmethod_worker_up): New typedef.
	(invoke_xmethod): Remove.
	(clone_xmethod_worker): Remove.
	(free_xmethod_worker): Remove.
	(free_xmethod_worker_vec): Remove.
	(get_xmethod_arg_types): Remove.
	(get_xmethod_result_type): Remove.
	* valops.c (find_method_list): Use std::vector, don't use
	intermediate vector.
	(value_find_oload_method_list): Use std::vector.
	(find_overload_match): Use std::vector.
	(find_oload_champ): Use std::vector.
	* value.c (value_free): Use operator delete.
	(value_of_xmethod): Rename to...
	(value_from_xmethod): ... this.  Don't assign
	xmethod_worker::value, take rvalue-reference.
	(result_type_of_xmethod): Adjust.
	(call_xmethod): Adjust.
	* value.h: Include extension.h.
	(struct xmethod_worker): Don't forward-declare.
	(value_of_xmethod): Rename to...
	(value_from_xmethod): ... this, take rvalue-reference.
	* python/py-xmethods.c (struct gdbpy_worker_data): Rename to...
	(struct python_xmethod_worker): ... this, add constructor and
	destructor.
	<invoke, clone, do_get_arg_types, do_get_result_type>: Implement.
	(gdbpy_free_xmethod_worker_data): Rename to...
	(python_xmethod_worker::~python_xmethod_worker): ... this and
	adjust.
	(gdbpy_clone_xmethod_worker_data): Rename to...
	(python_xmethod_worker::clone): ... this and adjust.
	(gdbpy_get_matching_xmethod_workers): Use std::vector, don't use
	temporary vector.
	(gdbpy_get_xmethod_arg_types): Rename to...
	(python_xmethod_worker::do_get_arg_types): ... this and adjust.
	(gdbpy_get_xmethod_result_type): Rename to...
	(python_xmethod_worker::do_get_result_type): ... this and
	adjust.
	(gdbpy_invoke_xmethod): Rename to...
	(python_xmethod_worker::invoke): ... this and adjust.
	(new_python_xmethod_worker): Rename to...
	(python_xmethod_worker::python_xmethod_worker): ... this and
	adjust.
	* python/python-internal.h (gdbpy_clone_xmethod_worker_data):
	Remove.
	(gdbpy_free_xmethod_worker_data): Remove.
	(gdbpy_get_matching_xmethod_workers): Use std::vector.
	(gdbpy_get_xmethod_arg_types): Remove.
	(gdbpy_get_xmethod_result_type): Remove.
	(gdbpy_invoke_xmethod): Remove.
	* python/python.c (python_extension_ops): Remove obsolete
	callbacks.

1 files changed, 13 insertions, 17 deletions

diff --git a/gdb/value.c b/gdb/value.c
index d4b4673..9a144fb 100644
--- a/gdb/value.c
+++ b/gdb/value.c
@@ -1627,7 +1627,7 @@ value_free (struct value *val)
 	    funcs->free_closure (val);
 	}
       else if (VALUE_LVAL (val) == lval_xcallable)
-	  free_xmethod_worker (val->location.xm_worker);
+	  delete val->location.xm_worker;
 
       xfree (val->contents);
       VEC_free (range_s, val->unavailable);
@@ -2697,23 +2697,20 @@ show_convenience (const char *ignore, int from_tty)
     }
 }
 
-/* Return the TYPE_CODE_XMETHOD value corresponding to WORKER.  */
+
+/* See value.h.  */
 
 struct value *
-value_of_xmethod (struct xmethod_worker *worker)
+value_from_xmethod (xmethod_worker_up &&worker)
 {
-  if (worker->value == NULL)
-    {
-      struct value *v;
+  struct value *v;
 
-      v = allocate_value (builtin_type (target_gdbarch ())->xmethod);
-      v->lval = lval_xcallable;
-      v->location.xm_worker = worker;
-      v->modifiable = 0;
-      worker->value = v;
-    }
+  v = allocate_value (builtin_type (target_gdbarch ())->xmethod);
+  v->lval = lval_xcallable;
+  v->location.xm_worker = worker.release ();
+  v->modifiable = 0;
 
-  return worker->value;
+  return v;
 }
 
 /* Return the type of the result of TYPE_CODE_XMETHOD value METHOD.  */
@@ -2724,8 +2721,8 @@ result_type_of_xmethod (struct value *method, int argc, struct value **argv)
   gdb_assert (TYPE_CODE (value_type (method)) == TYPE_CODE_XMETHOD
 	      && method->lval == lval_xcallable && argc > 0);
 
-  return get_xmethod_result_type (method->location.xm_worker,
-				  argv[0], argv + 1, argc - 1);
+  return method->location.xm_worker->get_result_type
+    (argv[0], argv + 1, argc - 1);
 }
 
 /* Call the xmethod corresponding to the TYPE_CODE_XMETHOD value METHOD.  */
@@ -2736,8 +2733,7 @@ call_xmethod (struct value *method, int argc, struct value **argv)
   gdb_assert (TYPE_CODE (value_type (method)) == TYPE_CODE_XMETHOD
 	      && method->lval == lval_xcallable && argc > 0);
 
-  return invoke_xmethod (method->location.xm_worker,
-			 argv[0], argv + 1, argc - 1);
+  return method->location.xm_worker->invoke (argv[0], argv + 1, argc - 1);
 }
 
 /* Extract a value as a C number (either long or double).