I observed a bug that ScoreComponentCollection core entries would retain their score even after ZeroAll(). This may have affected the Moses implementation of MIRA.
* std::valarray::resize(0) means "resize to 0" [1]
* subsequent accesses using operator[] result in undefined behavior [2]
FeatureVector::clear() is used by ScoreComponentCollection::ZeroAll(), which in turn was used in these places:
./contrib/mira/Main.cpp:665: cumulativeWeights.ZeroAll();
./contrib/mira/Main.cpp:666: cumulativeWeightsBinary.ZeroAll();
./moses/Incremental.cpp:580: features.ZeroAll();
It seems to me that the Moses implementation of MIRA may have been affected?
[1] http://www.cplusplus.com/reference/valarray/valarray/resize/
[2] http://www.cplusplus.com/reference/valarray/valarray/operator%5B%5D/