Re: [patch] Compilation regression with python-2.6 [Re: [PATCH 24/28] introduce gdb_pymodule_addobject]

Pedro Alves
2013-05-21T16:24:02Z

On 05/21/2013 05:14 PM, Jan Kratochvil wrote:
> On Tue, 21 May 2013 18:05:40 +0200, Pedro Alves wrote:
>> How about we handle this in a central place with something like:
>
> Fine with me although there is also Py_INCREF and not sure if also others.

Yeah. I guess we can handle those on an as needed basis.

Here's a complete patch, with ChangeLog.

I notice that py_decref could actually be using Py_XDECREF instead
of doing the explicit 'if (py)' check.

----
Subject: Centralize workaround for Python 2.6's Py_DECREF.

Wrap/redefine Py_DECREF ourselves, avoiding the need for uses to care
about extra braces due to the fact that Python only started wrapping Py_DECREF
in 'do {} while (0)' after 2.6.

gdb/
2013-05-21 Pedro Alves <palves@redhat.com>

* python/py-utils.c (py_decref): Remove extra braces.
(gdb_pymodule_addobject): Remove extra braces.
* python-internal.h (gdb_Py_DECREF): New static inline function.
(Py_DECREF): Redefine as calling gdb_Py_DECREF.

---

gdb/python/py-utils.c | 11 ++---------
gdb/python/python-internal.h | 12 ++++++++++++
2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/gdb/python/py-utils.c b/gdb/python/py-utils.c
index e78dee0..80bacf7 100644
--- a/gdb/python/py-utils.c
+++ b/gdb/python/py-utils.c
@@ -31,12 +31,8 @@ py_decref (void *p)
{
PyObject *py = p;

- /* Note that we need the extra braces in this 'if' to avoid a
- warning from gcc. */
if (py)
- {
- Py_DECREF (py);
- }
+ Py_DECREF (py);
}

/* Return a new cleanup which will decrement the Python object's
@@ -443,9 +439,6 @@ gdb_pymodule_addobject (PyObject *module, const char *name, PyObject *object)
Py_INCREF (object);
result = PyModule_AddObject (module, name, object);
if (result < 0)
- {
- /* Python 2.6 did not wrap Py_DECREF in do { } while (0);. */
- Py_DECREF (object);
- }
+ Py_DECREF (object);
return result;
}
diff --git a/gdb/python/python-internal.h b/gdb/python/python-internal.h
index b01efa1..b5c34b6 100644
--- a/gdb/python/python-internal.h
+++ b/gdb/python/python-internal.h
@@ -169,6 +169,18 @@ typedef unsigned long gdb_py_ulongest;

#endif /* HAVE_LONG_LONG */

+/* Python 2.6 did not wrap Py_DECREF in 'do {...} while (0)', leading
+ to 'suggest explicit braces to avoid ambiguous Â‘elseÂ’' gcc errors.
+ Wrap it ourselves, so that callers don't need to care. */
+
+static inline void
+gdb_Py_DECREF (void *op)
+{
+ Py_DECREF (op);
+}
+
+#undef Py_DECREF
+#define Py_DECREF(op) gdb_Py_DECREF (op)

/* In order to be able to parse symtab_and_line_to_sal_object function
a real symtab_and_line structure is needed. */