#fmt float precision is busted

[brson]

#fmt("%.100f, 1.1) results in 1.1000000000

printf's results in 1.10000000000000008881784197001252323389053344726562500... etc.

[kud1ing]

Maybe related to #1375?

[killerswan]

I've done some messing around with float formatting here (#2488), and while I haven't found where, yet, there's some kind of 100 character cutoff...

Code:

io::println(#fmt("%.2f", 1.1));
io::println(#fmt("%.50f", 1.1));
io::println(#fmt("%.75f", 1.1));
io::println(#fmt("%.90f", 1.1));
io::println(#fmt("%.99f", 1.1));
io::println(#fmt("%.100f", 1.1));

Output:

1.10
1.10000000000000008881784197001252323389053344726563
1.100000000000000088817841970012523233890533447265625000000000000000000000000
1.100000000000000088817841970012523233890533447265625000000000000000000000000000000000000000
1.100000000000000088817841970012523233890533447265625000000000000000000000000000000000000000000000000
1.1000000000