How to covert dchar and wchar to string?

[Q. Schroll]

On Monday, 25 January 2021 at 18:45:11 UTC, Rempas wrote:
> Actually what the title says. For example I have dchar c = 
> '\u03B3'; and I want to make it into string. I don't want to 
> use "to!string(c);". Any help?

char[] dcharToChars(char[] buffer, dchar value)
{
     import std.range : put;
     auto backup = buffer;
     put(buffer, value);
     return backup[0 .. $ - buffer.length];
}

void main()
{
     dchar c = '\u03B3';
     char[4] buffer;
     char[] protoString = dcharToChars(buffer, c);

     import std.stdio;
     writeln("'", protoString, "'");
}

Unfortunately, `put` is not @nogc in this case.