Some implicit array casts are missing

[dlangBugzillaToGithub]

Denis Shelomovskii (@denis-sh) reported this on 2014-04-04T06:37:07Z

Transferred from https://issues.dlang.org/show_bug.cgi?id=12519

Description

This code should compile:
---
void main()
{
    void[] va;
    byte[] ba;
    byte[1] sba;
    const byte[] cba;
    const byte[1] csba;
    va ~= ba; // ok
    va ~= sba; // ok
    va ~= cba; // Error: cannot append type const(byte[]) to type void[]
    va ~= csba; // Error: cannot append type const(byte[1]) to type void[]
}
---

[dlangBugzillaToGithub]

k.hara.pg commented on 2014-05-26T08:06:34Z

void[] is an array of untyped *mutable* data. So appending const data to mutable array will violate type system.

[dlangBugzillaToGithub]

verylonglogin.reg commented on 2014-05-26T13:23:47Z

(In reply to Kenji Hara from comment #1)
> void[] is an array of untyped *mutable* data. So appending const data to
> mutable array will violate type system.

But `byte` has no indirections so `const byte` is convertible to `byte` and this logically equivalent code is valid:
---
void main()
{
    void[] va;
    const byte[] cba;
    const byte[1] csba;
    byte[] tmp;
    tmp ~= cba;
    tmp ~= csba;
    va = tmp;
}
---