http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55911
Bug #: 55911
Summary: Segfault in unordered_map with max_load_factor > 1
Classification: Unclassified
Product: gcc
Version: 4.7.2
Status: UNCONFIRMED
Severity: major
Priority: P3
Component: libstdc++
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: t...@gtk.org
Created attachment 29114
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=29114
C++11 unordered_map segfault example
The attached test program segfaults when compiled and executed with the
following g++ versions:
g++-4.7 (Ubuntu/Linaro 4.7.2-11precise2) 4.7.2
g++-4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3
The program inserts values into an unordered_map and iterates over it's bucket
stats. Removing the line
> pmap.max_load_factor (50);
does not cause a segfault.
Example output:
$ g++ -g -Wall -O2 -std=gnu++0x -pthread umap-bug.cc && dbg ./a.out
unordered_map: max_size: 768614336404564650
unordered_map: size: 10352716
unordered_map: bucket_count: 218971
unordered_map: load_factor: 47.278938
unordered_map: max_load_factor: 50.000000
Program received signal SIGSEGV, Segmentation fault.
__distance<std::__detail::_Node_const_iterator<std::pair<long const, double>,
false, false> > (__last=..., __first=...)
at /usr/include/c++/4.6/bits/stl_iterator_base_funcs.h:82
82 ++__first;
(gdb) bt
#0 __distance<std::__detail::_Node_const_iterator<std::pair<long const,
double>, false, false> > (__last=..., __first=...)
at /usr/include/c++/4.6/bits/stl_iterator_base_funcs.h:82
#1 distance<std::__detail::_Node_const_iterator<std::pair<long const, double>,
false, false> > (__last=..., __first=...)
at /usr/include/c++/4.6/bits/stl_iterator_base_funcs.h:117
#2 bucket_size (__n=218971, this=0x7fffffffde30) at
/usr/include/c++/4.6/bits/hashtable.h:299
#3 unordered_map_bucket_stats<std::unordered_map<long, double, HashPtrdiff> >
(umap=...) at umap-bug.cc:16
#4 main (argc=<optimized out>, argv=<optimized out>) at umap-bug.cc:55
