Greetings,
The vector validity checks introduced here:
http://gcc.gnu.org/ml/gcc-patches/2011-09/msg00415.html
proved too strict: older versions of GCC used to do this:
_M_start = _M_end = _M_end_of_storage = new_allocator(sizeof(T) * n)
even when n == 0, and we have code compiled by such version linked in
with new code, and failing the check.
Google ref b/9198806
Attached patch relaxes the check, while still catching dangling vector
accesses.
Ok for google/gcc_4-7, gcc-4_8 and integration branches?
Thanks,
--
Paul Pluzhnikov
Index: libstdc++-v3/include/bits/stl_vector.h
===================================================================
--- libstdc++-v3/include/bits/stl_vector.h (revision 199461)
+++ libstdc++-v3/include/bits/stl_vector.h (working copy)
@@ -244,12 +244,27 @@
bool _M_is_valid() const
{
- return (this->_M_impl._M_end_of_storage == 0
- && this->_M_impl._M_start == 0
- && this->_M_impl._M_finish == 0)
- || (this->_M_impl._M_start <= this->_M_impl._M_finish
- && this->_M_impl._M_finish <= this->_M_impl._M_end_of_storage
- && this->_M_impl._M_start < this->_M_impl._M_end_of_storage);
+ if (this->_M_impl._M_end_of_storage == 0
+ && this->_M_impl._M_start == 0
+ && this->_M_impl._M_finish == 0)
+ return true;
+
+ if (this->_M_impl._M_start <= this->_M_impl._M_finish
+ && this->_M_impl._M_finish <= this->_M_impl._M_end_of_storage)
+ {
+ if (this->_M_impl._M_start < this->_M_impl._M_end_of_storage)
+ return true;
+ else if (this->_M_impl._M_start == this->_M_impl._M_end_of_storage
+ && this->_M_impl._M_start == this->_M_impl._M_finish)
+ {
+ pointer _0xcdcd;
+
+ __builtin_memset(&_0xcdcd, 0xcd, sizeof(_0xcdcd));
+ return this->_M_impl._M_finish != _0xcdcd;
+ }
+ }
+
+ return false;
}
public:
