These two containers are indeed collections, so their place is in
libcollections, not in libstd. There will always be a hash map as part of the
standard distribution of Rust, but by moving it out of the standard library it
makes libstd that much more portable to more platforms and environments.
This conveniently also removes the stuttering of 'std::hashmap::HashMap',
although 'collections::HashMap' is only one character shorter.
LinearMap is quite a bit faster, and is fully owned/sendable without
requiring copies. The older std::map also doesn't use explicit self and
relies on mutable fields.
needed.
Regarding soundness: there was a subtle bug in how it was done before; see the
compile-fail test for an example.
Regarding reborrowing: reborrowing allows mut and const
slices/borrowed-pointers to be used with pure fns that expect immutable data.
r=brson
