now() - Date(2020) fails with error

[sambitdash]

julia> now() - Date(2020)
MethodError: no method matching -(::DateTime, ::Date)
Closest candidates are:
  -(::DateTime, !Matched::Month) at D:\buildbot\worker\package_win64\build\usr\share\julia\stdlib\v1.5\Dates\src\arithmetic.jl:60
  -(::DateTime, !Matched::Year) at D:\buildbot\worker\package_win64\build\usr\share\julia\stdlib\v1.5\Dates\src\arithmetic.jl:31
  -(::DateTime, !Matched::Period) at D:\buildbot\worker\package_win64\build\usr\share\julia\stdlib\v1.5\Dates\src\arithmetic.jl:77
  ...

Stacktrace:
 [1] top-level scope at In[27]:1
 [2] include_string(::Function, ::Module, ::String, ::String) at .\loading.jl:1091
 [3] execute_code(::String, ::String) at D:\Users\sambi\.julia\packages\IJulia\a1SNk\src\execute_request.jl:27
 [4] execute_request(::ZMQ.Socket, ::IJulia.Msg) at D:\Users\sambi\.julia\packages\IJulia\a1SNk\src\execute_request.jl:86
 [5] #invokelatest#1 at .\essentials.jl:710 [inlined]
 [6] invokelatest at .\essentials.jl:709 [inlined]
 [7] eventloop(::ZMQ.Socket) at D:\Users\sambi\.julia\packages\IJulia\a1SNk\src\eventloop.jl:8
 [8] (::IJulia.var"#15#18")() at .\task.jl:356

A Base.:-(::DateTime, ::Date) should return a Period most likely in Millisecond as is with Base:-(::DateTime, ::DateTime).

Full discussion on the thread at: https://discourse.julialang.org/t/now-date-2020-errors/50890

[Keno]

I don't think this method should exist. A Date is not just a DateTime with time values set to 00:00:00. The time is deliberately unset. There's several ways to deliberate select what is requested, e.g. today() - Date(2020) or now() - DateTime(2020).

[Keno]

I guess the argument here would be that convert(DateTime, ::Date) exists, so by our general promotion rules it should work. However, this working still makes me unfomfortable - perhaps that conversion shouldn't exist.

[JeffBezanson]

Triage thinks this method should not exist, since a Date does not identify a point in time, but a DateTime does. In fact in 2.0 we should probably remove the convert methods that equate a Date with midnight UTC on that Date.