Macro ipv4_addr_from_env

macro_rules! ipv4_addr_from_env {
    ($env_var:literal, $doc:literal $(,)?) => { ... };
}

Reads an IPv4 address at compile time from the given environment variable, produces an Ipv4Addr.

Produces a compile-time error if the environment variable is not found. The $doc parameter allows to provide a documentation string for this tunable (see str_from_env!).

Produces a compile-time error when option_env! does.