Merge pull request #18629 from JuliaLang/teh/unsafe_trunc

Support unsafe_trunc(T, ::Integer)

Author: timholy

base/int.jl

@@ -327,6 +327,8 @@ rem{T<:Integer}(x::T, ::Type{T}) = x
 rem(x::Integer, ::Type{Bool}) = ((x&1)!=0)
 mod{T<:Integer}(x::Integer, ::Type{T}) = rem(x, T)
 
+unsafe_trunc{T<:Integer}(::Type{T}, x::Integer) = rem(x, T)
+
 convert{Tf<:Union{Float32,Float64}}(T::BitSigned64T, x::Tf) =
     box(T,checked_fptosi(T,unbox(Tf,x)))
 convert{Tf<:Union{Float32,Float64}}(T::BitUnsigned64T, x::Tf) =

test/int.jl

@@ -195,3 +195,9 @@ end
 @test true << 2 === 1 << 2
 @test true >> 2 === 1 >> 2
 @test true >>> 2 === 1 >>> 2
+
+@test @inferred(unsafe_trunc(Int8, 127)) === Int8(127)
+@test unsafe_trunc(Int8, 128) === Int8(-128)
+@test unsafe_trunc(Int8, -127) === Int8(-127)
+@test unsafe_trunc(Int8, -128) === Int8(-128)
+@test unsafe_trunc(Int8, -129) === Int8(127)