Will consteval allow to use static_assert on function arguments? No. Function arguments have never been, and will continue to not be, usable as constant expressions. There is a difference between something being constant evaluated and being usable as a constant-expression. consteval ensures that we’re in a constant evaluation context, but it does not also cause … Read more
Static assert is used to make assertions at compile time. When the static assertion fails, the program simply doesn’t compile. This is useful in different situations, like, for example, if you implement some functionality by code that critically depends on unsigned int object having exactly 32 bits. You can put a static assert like this … Read more
One other trick (which can be used in C) is to try to build an array with a negative size if the assert fail: #define ASSERT(cond) int foo[(cond) ? 1 : -1] as a bonus, you may use a typedef instead of an object, so that it is usable in more contexts and doesn’t takes … Read more
NEW ANSWER : In my original answer (below), I had to have two different macros to support assertions in a function scope and at the global scope. I wondered if it was possible to come up with a single solution that would work in both scopes. I was able to find a solution that worked … Read more
This is not valid C++11 code, because a constexpr function must only contain a return statement. This is incorrect. static_assert in a constexpr function are fine. What is not fine is using function parameters in constant expressions, like you do it. You could throw if x <= 0. Calling the function in a context that … Read more
The standard says in [temp.res]/8 No diagnostic shall be issued for a template definition for which a valid specialization can be generated. If no valid specialization can be generated for a template definition, and that template is not instantiated, the template definition is ill-formed, no diagnostic required. … [ Note: If a template is instantiated, … Read more
This is talking about a well-established rule for templates – the same rule that allows compilers to diagnose template<class> void f() { return 1; }. [temp.res]/8 with the new change bolded: The program is ill-formed, no diagnostic required, if: no valid specialization can be generated for a template or a substatement of a constexpr if … Read more
C11 standard adds the _Static_assert keyword. This is implemented since gcc-4.6: _Static_assert (0, “assert1”); /* { dg-error “static assertion failed: \”assert1\”” } */ The first slot needs to be an integral constant expression. The second slot is a constant string literal which can be long (_Static_assert(0, L”assertion of doom!”)). I should note that this is … Read more