On Tuesday, 22 September 2015 at 14:53:54 UTC, Ola Fosheim
The consequences of a C function mutating something reachable
through const is either a disaster or the D compiler will have
to forget about those kind of optimizations after calling a C
function. But then const has very little value...
Another C feature you didn't know about: the standard allows to
create a mutable pointer to const data and mutate it. But most of
the time when you see const in C, it works as expected, so
usually there shouldn't be a problem except for mangling.