add conversions from float to BigInt. ref JuliaLang#6183

base/gmp.jl

@@ -59,12 +59,21 @@ function BigInt(x::Union(Clong,Int32))
 end
 function BigInt(x::Union(Culong,Uint32))
  z = BigInt()
- ccall((:__gmpz_set_ui, :libgmp), Void,(Ptr{BigInt}, Culong), &z, x)
+ ccall((:__gmpz_set_ui, :libgmp), Void, (Ptr{BigInt}, Culong), &z, x)
  return z
 end
 
 BigInt(x::Bool) = BigInt(uint(x))
 
+function BigInt(x::Float64)
+ !isinteger(x) && throw(InexactError())
+ z = BigInt()
+ ccall((:__gmpz_set_d, :libgmp), Void, (Ptr{BigInt}, Cdouble), &z, x)
+ return z
+end
+
+BigInt(x::Union(Float16,Float32)) = BigInt(float64(x))
+
 function BigInt(x::Integer)
  if x < 0
  if typemin(Clong) <= x
@@ -94,6 +103,7 @@ function BigInt(x::Integer)
 end
 
 convert(::Type{BigInt}, x::Integer) = BigInt(x)
+convert(::Type{BigInt}, x::FloatingPoint) = BigInt(x)
 
 function convert(::Type{Int64}, x::BigInt)
  lo = int64(convert(Culong, x & typemax(Uint32)))

base/mpfr.jl

@@ -78,12 +78,11 @@ BigFloat(x::Integer) = BigFloat(BigInt(x))
 BigFloat(x::Union(Bool,Int8,Int16,Int32)) = BigFloat(convert(Clong,x))
 BigFloat(x::Union(Uint8,Uint16,Uint32)) = BigFloat(convert(Culong,x))
 
-BigFloat(x::Union(Float16,Float32,Float16)) = BigFloat(float64(x))
+BigFloat(x::Union(Float16,Float32)) = BigFloat(float64(x))
 BigFloat(x::Rational) = BigFloat(num(x)) / BigFloat(den(x))
 
 convert(::Type{Rational}, x::BigFloat) = convert(Rational{BigInt}, x)
 convert(::Type{BigFloat}, x::Rational) = BigFloat(x) # to resolve ambiguity
-convert(::Type{BigFloat}, x::Float16) = BigFloat(x) # to resolve ambiguity
 convert(::Type{BigFloat}, x::Real) = BigFloat(x)
 convert(::Type{FloatingPoint}, x::BigInt) = BigFloat(x)
 
@@ -107,12 +106,9 @@ for to in (Uint8, Uint16, Uint32, Uint64)
  end
 end
 
-function convert(::Type{BigInt}, x::BigFloat)
- if isinteger(x)
- return itrunc(x)
- else
- throw(InexactError())
- end
+function Base.BigInt(x::BigFloat)
+ !isinteger(x) && throw(InexactError())
+ return itrunc(x)
 end
 convert(::Type{Float64}, x::BigFloat) =
  ccall((:mpfr_get_d,:libmpfr), Float64, (Ptr{BigFloat},Int32), &x, ROUNDING_MODE[end])

test/bigint.jl

@@ -271,3 +271,8 @@ ndigits_mismatch(n) = ndigits(n) != ndigits(BigInt(n))
 @test !any(ndigits_mismatch, 64:99)
 @test !any(ndigits_mismatch, 512:999)
 @test !any(ndigits_mismatch, 8192:9999)
+
+# conversion from float
+@test BigInt(2.0) == BigInt(2.0f0) == BigInt(big(2.0)) == 2
+@test_throws convert(BigInt, 2.1)
+@test_throws convert(BigInt, big(2.1))