Inconsistent behavior in safe checking of conversion to void

[dlangBugzillaToGithub]

Walter Bright reported this on 2024-11-18T18:36:48Z

Transferred from https://issues.dlang.org/show_bug.cgi?id=24866

CC List

• Richard (Rikki) Andrew Cattermole

Description

```
@safe:

struct T { int* a,b,c; }

void bar(void[24]);
void gee(void*);

void test() {
    static T t;
    gee(&t);              // no error
    bar(cast(void[24])t); // cast from `T` to `void[24]` not allowed in safe code
}
```
Both should be allowed or both should error.

[dlangBugzillaToGithub]

alphaglosined commented on 2024-11-18T19:00:06Z

Due to placement new, I'm on the side of disallowing conversion to ``void*`` and ``void[]`` in ``@safe``.

We have been relying on a language feature like that not existing and it opens up a major can of worms to have it.

Related: https://issues.dlang.org/show_bug.cgi?id=24772