Revert "fix mod for mixes of Signed and Unsigned (#57853)"

This reverts commit 9b474fa.

Author: KristofferC

base/int.jl

@@ -286,14 +286,8 @@ function mod(x::T, y::T) where T<:Integer
     y == -1 && return T(0)   # avoid potential overflow in fld
     return x - fld(x, y) * y
 end
-function mod(x::BitSigned, y::Unsigned)
-    remval = rem(x, y) # correct iff  remval>=0
-    return unsigned(remval + (remval<zero(remval))*y)
-end
-function mod(x::Unsigned, y::Signed)
-    remval =  signed(rem(x, y)) #remval>0 so correct iff y>0 or remval==0
-    return remval + (!iszero(remval) && y<zero(y))*y
-end
+mod(x::BitSigned, y::Unsigned) = rem(y + unsigned(rem(x, y)), y)
+mod(x::Unsigned, y::Signed) = rem(y + signed(rem(x, y)), y)
 mod(x::T, y::T) where {T<:Unsigned} = rem(x, y)
 
 # Don't promote integers for div/rem/mod since there is no danger of overflow,

test/int.jl

@@ -358,23 +358,6 @@ end
             end
         end
     end
-    # exhaustive UInt8/Int8 tests for mixed signedness
-    for f in (mod, rem)
-        for i in -128:127
-            for j in 0:255
-                if iszero(i)
-                    @test_throws DivideError f(UInt8(j), Int8(i))
-                else
-                    @test f(UInt8(j), Int8(i)) == f(j, i)
-                end
-                if iszero(j)
-                    @test_throws DivideError f(Int8(i), UInt8(j))
-                else
-                    @test f(Int8(i), UInt8(j)) == f(i,j)
-                end
-            end
-        end
-    end
 end
 
 @testset "Underscores in big_str" begin