Not public: the best instrumented profiler I’ve ever used. Smaller things like Assert tags so you can uniquely ID them. A massive distributed test system (love hate with that one). Profiling and optimization tools to answer pretty much any question about how your product behaves.
I always thought MSVC’s dialect of C++ was a little more programmer friendly. E.g. you can construct an object inline and pass it by reference. The compiler doesn’t do ridiculous things once it finds out you sign overflowed - it’s designed to support applications not meet synthetic benchmarks. PDBs make a lot more sense to me than packing debug info directly in the binary.