Compat for #11922 (MathConst -> Irrational)

Fixes #108

Author: simonster

Diff for: README.md

@@ -63,6 +63,8 @@ Currently, the `@compat` macro supports the following syntaxes:
   Julia 0.4, using these types also checks whether the string has embedded
   NUL characters [#10994](https://github.com/JuliaLang/julia/pull/10994).)
 
+* `typealias Irrational MathConst` - `MathConst` has been renamed to `Irrational` [#11922](https://github.com/JuliaLang/julia/pull/11922)
+
 ## New functions
 
 * `eachindex`, as in `for i in eachindex(A)`, can be used in julia 0.3. This is the recommended way to iterate over each index in an `AbstractArray`. On julia 0.3 `eachindex` just returns `1:length(A)`, but in julia 0.4 it can return a more sophisticated iterator.
@@ -111,6 +113,8 @@ Currently, the `@compat` macro supports the following syntaxes:
 
 * `zero(Ptr{T})` is now `Ptr{T}(0)` [#8909](https://github.com/JuliaLang/julia/pull/8909)
 
+* The unexported macro `Base.@math_const` was renamed to `Base.@irrational`, accessible as `Compat.@irrational` on either 0.3 or 0.4 [#11922](https://github.com/JuliaLang/julia/pull/11922)
+
 ## New types
 
 * [`Nullable` types](http://julia.readthedocs.org/en/latest/manual/types/?highlight=nullable#nullable-types-representing-missing-values) and their associated operations.

Diff for: src/Compat.jl

@@ -459,4 +459,12 @@ if VERSION < v"0.4.0-dev+5322"
     include("timer.jl")
 end
 
+if VERSION < v"0.4.0-dev+5688"
+    typealias Irrational MathConst
+    @eval const $(symbol("@irrational")) = getfield(Base, symbol("@math_const"))
+    export Irrational
+else
+    import Base.@irrational
+end
+
 end # module

Diff for: test/runtests.jl

@@ -357,3 +357,9 @@ let c = 0, f, t
     sleep(0.1)
     @test val == c
 end
+
+# MathConst -> Irrational
+f(::Irrational) = true
+@test f(π)
+Compat.@irrational mathconst_one 1.0 big(1.)
+@test f(mathconst_one)