> We all know that strlen will return 5, but some compilers don't: https://godbolt.org/z/M7x5qraE6 https://godbolt.org/z/M7x5qraE6 I feel like it is unfair to

> We all know that strlen will return 5, but some compilers don't: https://godbolt.org/z/M7x5qraE6 https://godbolt.org/z/M7x5qraE6 I feel like it is unfair to blame the compiler when you've explicitly asked for `/O1`. If you change this to `/O2` or `/Ox` then MSVC will optimize this into a constant 5, proving that it does "know" that strlen will return 5 in this case.