| Message ID | 20160919171125.GA31777@redhat.com |
|---|---|
| State | New |
| Headers | show |
Python has a distinct integer division operator, "//". 7 // 3 returns the integer 2.
-----Original Message-----
From: libstdc++-owner@gcc.gnu.org [mailto:libstdc++-owner@gcc.gnu.org] On Behalf Of Jonathan Wakely
Sent: Monday, September 19, 2016 10:11 AM
To: libstdc++@gcc.gnu.org; gcc-patches@gcc.gnu.org
Subject: [PATCH] libstdc++/77645 fix deque and vector xmethods for Python 3
The problem for these xmethods is that in Python 3 division of two integers produces a float, and GDB then doesn't allow that value to be used for pointer arithmetic (https://sourceware.org/PR20622).
PR libstdc++/77645
* python/libstdcxx/v6/xmethods.py (DequeWorkerBase.__init__)
(DequeWorkerBase.index, VectorWorkerBase.get): Cast results of
division to int to work with Python 3.
Tested x86_64-linux, committed to trunk.
I'll fix it for gcc-5 and gcc-6 too.
On 19/09/16 17:24 +0000, Joe Buck wrote:
>Python has a distinct integer division operator, "//". 7 // 3 returns the integer 2.
Python 3 does, but Python 2 doesn't have it unless you import it from
__future, and I don't know how far back that works. I don't want to
introduce a fix for Python 3 that breaks it for old systems.
Using a cast is clear and (AFAIK) works with all versions.
On Mon, 19 Sep 2016, Jonathan Wakely wrote: > On 19/09/16 17:24 +0000, Joe Buck wrote: > > Python has a distinct integer division operator, "//". 7 // 3 returns the > > integer 2. > > Python 3 does, but Python 2 doesn't have it unless you import it from > __future, and I don't know how far back that works. I don't want to > introduce a fix for Python 3 that breaks it for old systems. No, // is available in Python, without needing __future__, from 2.2 onwards.
diff --git a/libstdc++-v3/python/libstdcxx/v6/xmethods.py b/libstdc++-v3/python/libstdcxx/v6/xmethods.py index 95f9af9..71a5b75 100644 --- a/libstdc++-v3/python/libstdcxx/v6/xmethods.py +++ b/libstdc++-v3/python/libstdcxx/v6/xmethods.py @@ -165,7 +165,7 @@ class ArrayMethodsMatcher(gdb.xmethod.XMethodMatcher): class DequeWorkerBase(gdb.xmethod.XMethodWorker): def __init__(self, val_type): self._val_type = val_type - self._bufsize = (512 / val_type.sizeof) or 1 + self._bufsize = int(512 / val_type.sizeof) or 1 def size(self, obj): first_node = obj['_M_impl']['_M_start']['_M_node'] @@ -176,7 +176,7 @@ class DequeWorkerBase(gdb.xmethod.XMethodWorker): def index(self, obj, idx): first_node = obj['_M_impl']['_M_start']['_M_node'] - index_node = first_node + idx / self._bufsize + index_node = first_node + int(idx / self._bufsize) return index_node[0][idx % self._bufsize] class DequeEmptyWorker(DequeWorkerBase): @@ -419,7 +419,7 @@ class VectorWorkerBase(gdb.xmethod.XMethodWorker): if self._val_type.code == gdb.TYPE_CODE_BOOL: start = obj['_M_impl']['_M_start']['_M_p'] bit_size = start.dereference().type.sizeof * 8 - valp = start + index / bit_size + valp = start + int(index / bit_size) offset = index % bit_size return (valp.dereference() & (1 << offset)) > 0 else:
The problem for these xmethods is that in Python 3 division of two integers produces a float, and GDB then doesn't allow that value to be used for pointer arithmetic (https://sourceware.org/PR20622). PR libstdc++/77645 * python/libstdcxx/v6/xmethods.py (DequeWorkerBase.__init__) (DequeWorkerBase.index, VectorWorkerBase.get): Cast results of division to int to work with Python 3. Tested x86_64-linux, committed to trunk. I'll fix it for gcc-5 and gcc-6 too. commit a1eda07dc44e271ea07c266624b600cbae257b58 Author: Jonathan Wakely <jwakely@redhat.com> Date: Mon Sep 19 18:02:36 2016 +0100 libstdc++/77645 fix deque and vector xmethods for Python 3 PR libstdc++/77645 * python/libstdcxx/v6/xmethods.py (DequeWorkerBase.__init__) (DequeWorkerBase.index, VectorWorkerBase.get): Cast results of division to int to work with Python 3.