GSL currently causes Clang Tidy to go nuts for several reasons:
1) there are several checks that fail because of UnitTest++
2) there are several checks that fail simply because we need to clean up some issues
3) the Core Guideline checks clearly fail since we are implementing the GSL
Adding this macro prevents Clang Tidy and other tools (like coverage tools) from registering the GSL as code the belongs to the project.
* constexpr all the things.
* remove operator=(const T&)
* it leaves *this in an invalid state if ensure_invariant fails
* implicitly converting the T to not_null and then assigning is in every way superior.
* simplify conversion from not_null<U> with constructor delegation.
* remove the converting assignment operator; again let the conversion constructor and self-assignment operator do the work.
* Cover the remaining pointer arithmetic operations as Wakely suggests in issue #447.
* Cleanup not_null conversions from null pointer constants:
* replace constructor that accepts T with constructor template that accepts U convertible to T
* remove deleted constructor that accepts int
* Attempts to initialize with nullptr, 0, 0L, 0LL, etc. all unambiguously select the deleted nullptr_t constructor.
* Nest "gsl" directory inside a new "include" directory.
* Cleanup the _MSC_VER conditionals a bit; use constexpr on VS2017+.
* Don't #define noexcept on non-Microsoft implementations.
* Workaround VS2017 bug in multi_span. (Also implement == and != for static_bounds_dynamic_range_t because I'm an EoP semantic soundness snob.)
Fixes#441.
