As I alluded to in this post, we're testing our STL with Clang (currently Clang/LLVM 4.0, soon to be 5.0 when I figure out how to get it to find my link.exe), and with libc++'s test suite. This has improved both our STL and Clang/libc++ upstream, and I'm grateful to their devs for working with us.
I'm also really hoping someone hasn't commented about Rust since I've been writing this...
We test our development builds against a large and growing number of open-source projects, but I don't think Ceres Solver is in our test matrix yet (I could be wrong).
I know, windows.h has something similar, but I'd prefer to have standard features available.