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libstdc++: Fix std::deque::size() Xmethod [PR112491]

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The Xmethod for std::deque::size() assumed that the first element would
be at the start of the first node. That's only true if elements are only
added at the back. If an element is inserted at the front, or removed
from the front (or anywhere before the middle) then the first node will
not be completely populated, and the Xmethod will give the wrong result.

libstdc++-v3/ChangeLog:

	PR libstdc++/112491
	* python/libstdcxx/v6/xmethods.py (DequeWorkerBase.size): Fix
	calculation to use _M_start._M_cur.
	* testsuite/libstdc++-xmethods/deque.cc: Check failing cases.
This commit is contained in:
Jonathan Wakely 2023-11-14 15:08:13 +00:00
parent 8f331be429
commit 4db8209280
2 changed files with 28 additions and 5 deletions
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13
libstdc++-v3/python/libstdcxx/v6/xmethods.py
View file

@ -193,11 +193,14 @@ class DequeWorkerBase(gdb.xmethod.XMethodWorker):
self._bufsize = 512 // val_type.sizeof or 1
def size(self, obj):
first_node = obj['_M_impl']['_M_start']['_M_node']
last_node = obj['_M_impl']['_M_finish']['_M_node']
cur = obj['_M_impl']['_M_finish']['_M_cur']
first = obj['_M_impl']['_M_finish']['_M_first']
return (last_node - first_node) * self._bufsize + (cur - first)
start = obj['_M_impl']['_M_start']
finish = obj['_M_impl']['_M_finish']
if not start['_M_node']:
return 0
return (self._bufsize
* (finish['_M_node'] - start['_M_node'] - 1)
+ (finish['_M_cur'] - finish['_M_first'])
+ (start['_M_last'] - start['_M_cur']))
def index(self, obj, idx):
first_node = obj['_M_impl']['_M_start']['_M_node']

20
libstdc++-v3/testsuite/libstdc++-xmethods/deque.cc
View file

@ -67,6 +67,26 @@ main ()
// { dg-final { whatis-test q1.back() int } }
// { dg-final { whatis-test q3\[0\] int } }
// PR libstdc++/112491
std::deque<int> q5;
q5.push_front(0);
// { dg-final { note-test q5.size() 1 } }
std::deque<int> q6 = q1;
q6.pop_front();
// { dg-final { note-test {q6.size() == (q1_size-1)} true } }
std::deque<int> q7 = q2;
q7.pop_front();
q7.pop_front();
// { dg-final { note-test {q7.size() == (q2_size-2)} true } }
std::deque<int> q8 = q3;
q8.pop_front();
q8.pop_front();
q8.pop_front();
// { dg-final { note-test {q8.size() == (q3_size-3)} true } }
std::deque<int> q9 = q8;
q9.clear();
// { dg-final { note-test q9.size() 0 } }
return 0; // Mark SPOT
}