Related: dmlc/xgboost#3976.
Currently, base64 stream stores EOF in a char variable, which may cause undefined behavior for ARM targets.
Details. std::istream.get() and getchar() have return type int, not char, because both may return EOF, which is commonly -1. Storing EOF in a char results in undefined behavior. The char type is usually signed on x86 systems but unsigned on ARM systems (see http://blog.cdleary.com/2012/11/arm-chars-are-unsigned-by-default/), so the undefined behavior will only be apparent when compiled on ARM.
Aside. AWS has recently begun offering ARM-backed EC2 instances.
Related: dmlc/xgboost#3976.
Currently, base64 stream stores EOF in a
charvariable, which may cause undefined behavior for ARM targets.Details.
std::istream.get()andgetchar()have return typeint, notchar, because both may return EOF, which is commonly -1. Storing EOF in acharresults in undefined behavior. Thechartype is usually signed on x86 systems but unsigned on ARM systems (see http://blog.cdleary.com/2012/11/arm-chars-are-unsigned-by-default/), so the undefined behavior will only be apparent when compiled on ARM.Aside. AWS has recently begun offering ARM-backed EC2 instances.