ints.choice vs. chars.choice

[mipri]

Howdy,

The following program fails to compile if the second line
is uncommented:

import std;

void main() {
     writeln([1, 2, 3].choice);
     //writeln(['a', 'b', 'c'].choice);
}

Error: template std.random.choice cannot deduce function from 
argument types !()(char[], MersenneTwisterEngine!(uint, 32LU, 
624LU, 397LU, 31LU, 2567483615u, 11LU, 4294967295u, 7LU, 
2636928640u, 15LU, 4022730752u, 18LU, 1812433253u)), candidates 
are:
/usr/include/dmd/phobos/std/random.d(2559):        
std.random.choice(Range, RandomGen = Random)(auto ref Range 
range, ref RandomGen urng) if (isRandomAccessRange!Range && 
hasLength!Range && isUniformRNG!RandomGen)
/usr/include/dmd/phobos/std/random.d(2569):        
std.random.choice(Range)(auto ref Range range)

What is going on here? I get it that choice() isn't simply an 
algorithm
over T[], that there are some additional constraints, but surely a
char[] is just as random acc...

...

Oh. It's because of emojicode.

This works:

import std;

void main() {
     writeln([1, 2, 3].choice);
     writeln(cast(char)(cast(uint8_t[])['a', 'b', 'c']).choice);
}

and this outputs false: writeln(isRandomAccessRange!(char[]));

I no longer have any questions but I wish the dlang.org docs were
much more generous with examples.