[Issue 19256] std.json: JSONValue allows violating constness

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19256

--- Comment #1 from FeepingCreature <default_357-line at yahoo.de> ---
See also bug 12885. https://issues.dlang.org/show_bug.cgi?id=12885

This bug is still relevant, as it happens in @safe code, not just @system -
std.json violates @trusted by allowing bad things to happen.

--