Hoom, hum, I met a dark forest of complains from the compilers here.

I walk slowly, but I would love typedef and cookies..

"""
import std.datetime, std.typecons;

alias M = Typedef!Duration;
void main()
{
    auto d1 = 100.msecs;
    auto d2 = 110.msecs;
    assert(d1 < d2);

    auto m1 = M(100.msecs);
    auto m2 = M(110.msecs);
    assert(m1 < m2);
}

/dlang/dmd/linux/bin64/../../src/phobos/std/typecons.d(6736): Error: template std.typecons.Typedef!(Duration, Duration(0L), null).Typedef.Proxy!(Typedef_payload).opCmp cannot deduce function from argument types !()(Duration), candidates are:
/dlang/dmd/linux/bin64/../../src/phobos/std/typecons.d(6726):        opCmp(this X, B)(auto ref B b)
  with X = Typedef!(Duration, Duration(0L), null),
       B = Duration
  must satisfy one of the following constraints:
       !is(typeof(a.opCmp(b)))
       !is(typeof(b.opCmp(a)))
/dlang/dmd/linux/bin64/../../src/phobos/std/typecons.d(6736): Error: template std.typecons.Typedef!(Duration, Duration(0L), null).Typedef.Proxy!(Typedef_payload).opCmp cannot deduce function from argument types !()(Duration), candidates are:
/dlang/dmd/linux/bin64/../../src/phobos/std/typecons.d(6726):        opCmp(this X, B)(auto ref B b)
  with X = Typedef!(Duration, Duration(0L), null),
       B = Duration
  must satisfy one of the following constraints:
       !is(typeof(a.opCmp(b)))
       !is(typeof(b.opCmp(a)))
onlineapp.d(16): Error: template instance std.typecons.Typedef!(Duration, Duration(0L), null).Typedef.Proxy!(Typedef_payload).opCmp!(Typedef!(Duration, Duration(0L), null), Typedef!(Duration, Duration(0L), null)) error instantiating
"""

On Saturday, 30 November 2019 at 18:15:47 UTC, Treebeard wrote:
> Hoom, hum, I met a dark forest of complains from the compilers here.
>
> [...]

/me thinks it's a bug

Pushed a pr. Let's see.

https://github.com/dlang/phobos/pull/7298