Merge pull request JuliaLang#14302 from eschnett/eschnett/flipsign2

Don't promote flipsign arguments for signed integers

base/int.jl

@@ -33,7 +33,7 @@ for T in (Int8,Int16,Int32,Int64,Int128)
  @eval flipsign(x::$T, y::$T) = box($T,flipsign_int(unbox($T,x),unbox($T,y)))
 end
 
-flipsign(x::Signed, y::Signed) = flipsign(promote(x,y)...)
+flipsign(x::Signed, y::Signed) = convert(typeof(x), flipsign(promote(x,y)...))
 flipsign(x::Signed, y::Float16) = flipsign(x, reinterpret(Int16,y))
 flipsign(x::Signed, y::Float32) = flipsign(x, reinterpret(Int32,y))
 flipsign(x::Signed, y::Float64) = flipsign(x, reinterpret(Int64,y))

test/int.jl

@@ -17,6 +17,20 @@ for y in (4, Float32(4), 4.0, big(4.0))
  @test copysign(-3, y) == 3
 end
 
+# Result type must be type of first argument
+for T in (Int8,Int16,Int32,Int64,Int128,BigInt,
+ UInt8,UInt16,UInt32,UInt64,UInt128,
+ Rational{Int},Rational{BigInt},
+ Float16,Float32,Float64)
+ for U in (Int8,Int16,Int32,Int64,Int128,BigInt,
+ Rational{Int},Rational{BigInt},
+ UInt8,UInt16,UInt32,UInt64,UInt128,
+ Float16,Float32,Float64)
+ @test typeof(copysign(T(3), U(4))) === T
+ @test typeof(flipsign(T(3), U(4))) === T
+ end
+end
+
 for s1 in (-1,+1), s2 in (-1,+1)
  @test flipsign(Int16(3s1), Float16(3s2)) === Int16(3s1*s2)
  @test flipsign(Int32(3s1), Float32(3s2)) === Int32(3s1*s2)