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* [gcc r9-10058] libstdc++: Do not allocate a zero-size vector<bool> [PR 100153]
@ 2022-05-09 16:40 Jonathan Wakely
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From: Jonathan Wakely @ 2022-05-09 16:40 UTC (permalink / raw)
To: gcc-cvs, libstdc++-cvs
https://gcc.gnu.org/g:b4a170bf3a2b0397a5d73f7cac24f6df4298569e
commit r9-10058-gb4a170bf3a2b0397a5d73f7cac24f6df4298569e
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Tue Apr 20 16:16:13 2021 +0100
libstdc++: Do not allocate a zero-size vector<bool> [PR 100153]
The vector<bool>::shrink_to_fit() implementation will allocate new
storage even if the vector is empty. That then leads to the
end-of-storage pointer being non-null and equal to the _M_start._M_p
pointer, which means that _M_end_addr() has undefined behaviour.
The fix is to stop doing a useless zero-sized allocation in
shrink_to_fit(), so that _M_start._M_p and _M_end_of_storage are both
null after an empty vector shrinks.
Signed-off-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
PR libstdc++/100153
* include/bits/vector.tcc (vector<bool>::_M_shrink_to_fit()):
When size() is zero just deallocate and reset.
(cherry picked from commit 681707ec28d56494fa61a80c62500724d55f8586)
Diff:
---
libstdc++-v3/include/bits/vector.tcc | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/libstdc++-v3/include/bits/vector.tcc b/libstdc++-v3/include/bits/vector.tcc
index 497d9f72247..7d56c63134a 100644
--- a/libstdc++-v3/include/bits/vector.tcc
+++ b/libstdc++-v3/include/bits/vector.tcc
@@ -944,7 +944,13 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
return false;
__try
{
- _M_reallocate(size());
+ if (size_type __n = size())
+ _M_reallocate(__n);
+ else
+ {
+ this->_M_deallocate();
+ this->_M_impl._M_reset();
+ }
return true;
}
__catch(...)
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