Add Compat.Dates for standard library Dates (#413)

* Add Compat.Dates for standard library Dates

* Refactor deprecated parametic syntax

README.md

@@ -83,6 +83,9 @@ Currently, the `@compat` macro supports the following syntaxes:
   Compat.DelimitedFiles` are provided on versions older than 0.7, where these are not yet
   part of the standard library. ([#23931])
 
+* `using Compat.Dates` is provided on versions older than 0.7, where this library is not
+  yet a part of the standard library. ([#24459])
+
 ## Module Aliases
 
 * In 0.6, some 0.5 iterator functions have been moved to the `Base.Iterators`
@@ -357,4 +360,5 @@ includes this fix. Find the minimum version from there.
 [#24047]: https://github.com/JuliaLang/julia/issues/24047
 [#24282]: https://github.com/JuliaLang/julia/issues/24282
 [#24372]: https://github.com/JuliaLang/julia/issues/24372
+[#24459]: https://github.com/JuliaLang/julia/issues/24459
 [#24657]: https://github.com/JuliaLang/julia/issues/24657

src/Compat.jl

@@ -695,6 +695,12 @@ else
     import Test, SharedArrays, Mmap, DelimitedFiles
 end
 
+if VERSION < v"0.7.0-DEV.2575"
+    const Dates = Base.Dates
+else
+    import Dates
+end
+
 # 0.7.0-DEV.1993
 @static if !isdefined(Base, :EqualTo)
     if VERSION >= v"0.6.0"

test/runtests.jl

@@ -645,6 +645,8 @@ cm359() = @__MODULE__
 
 # PR 21378
 let
+    import Compat: Dates
+
     # https://en.wikipedia.org/wiki/Swatch_Internet_Time
     eval(Expr(
         :type, false,
@@ -657,7 +659,7 @@ let
     Dates.toms(b::Beat) = Dates.value(b) * 86400
     Dates._units(b::Beat) = " beat" * (abs(Dates.value(b)) == 1 ? "" : "s")
     Base.promote_rule(::Type{Dates.Day}, ::Type{Beat}) = Dates.Millisecond
-    Base.convert{T<:Dates.Millisecond}(::Type{T}, b::Beat) = T(Dates.toms(b))
+    Base.convert(::Type{Dates.Millisecond}, b::Beat) = Dates.Millisecond(Dates.toms(b))
 
     @test Beat(1000) == Dates.Day(1)
     @test Beat(1) < Dates.Day(1)
@@ -847,6 +849,14 @@ module Test23876
     @test isdefined(Mmap, :mmap)
 end
 
+# 0.7
+module Test24459
+    using Compat
+    using Compat.Test
+    using Compat.Dates
+    @test isdefined(@__MODULE__, :Dates)
+end
+
 let a = [0,1,2,3,0,1,2,3]
     @test findfirst(equalto(3), [1,2,4,1,2,3,4]) == 6
     @test findfirst(!equalto(1), [1,2,4,1,2,3,4]) == 2