On Thursday, 22 June 2017 at 18:38:59 UTC, Boris-Barboris wrote:
On Thursday, 22 June 2017 at 13:56:29 UTC, ag0aep6g wrote:
For example, the type system guarantees that immutable data
never changes. But the compiler allows you to cast from
immutable to mutable and change the data. It's an invalid
operation, but the compiler is not expected to catch that for
you.
Casts are part of the type system. Yes, D type system allows
invalid operations. It's not the compiler's fault, it's type
system's fault.
unittest
{
immutable int a = 4;
int* b = cast(int*) &a;
*b = 5;
assert(*(&a) == 5);
assert(a == 4);
}
Here it's the programmer's fault really. You should never use
casts in normal code, cast is the ultimate switch to say "Look, I
know what I'm doing, so disable all safety, don't try to make
sense of it, and let me do my thing. If I'm telling you it's a
cat, then it is dammit.". You can't blame the type system not to
do something coherent here, you explicitely went out of your way
to lie to that very same type system in the most unsafe way
possible.
