constexpr vs const vs constexpr const

Question

const-vs-constexpr-on-variables

What the guy says about constexpr is right if double is used (or float of course). However, if you change t

Answer 1

From the comments it seems like OP is asking for Standard quote which defines const int as a compile-time constant, but const double as not.

The corresponding details are found in 5.19, Constant Expressions. In particular:

...an lvalue-to-rvalue conversion (4.1) unless it is applied to a non-volatile glvalue of integral or enumeration type that refers to a non-volatile const object with a preceding initialization, initialized with a constant expression...

int is an integral type, while double is not.