[analyzer] Don't assume values bound to references are automatically non-null.

While there is no such thing as a "null reference" in the C++ standard,
many implementations of references (including Clang's) do not actually
check that the location bound to them is non-null. Thus unlike a regular
null dereference, this will not cause a problem at runtime until the
reference is actually used. In order to catch these cases, we need to not
prune out paths on which the input pointer is null.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@161288 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed