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/ChangeLog

@@ -1,3 +1,10 @@
+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.
+
 2013-05-21  Philippe Waroquiers  <philippe.waroquiers@skynet.be>
 
 	* breakpoints.c (detach_breakpoints): Do not

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;
 }

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 ‘else’' 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.  */