include system/countbits_impl

lib/pure/bitops.nim

@@ -491,7 +491,7 @@ func countSetBits*(x: SomeInteger): int {.inline.} =
     doAssert countSetBits(0b0000_0011'u8) == 2
     doAssert countSetBits(0b1010_1010'u8) == 4
 
-  result = countSetBitsImpl(x)
+  result = countSetBitsSysimpl(x)
 
 func popcount*(x: SomeInteger): int {.inline.} =
   ## Alias for `countSetBits <#countSetBits,SomeInteger>`_ (Hamming weight).

lib/pure/math.nim

@@ -58,7 +58,6 @@ import std/private/since
                        # of the standard library!
 
 import std/[bitops, fenv]
-import system/countbits_impl
 
 when defined(nimPreviewSlimSystem):
   import std/assertions
@@ -1302,7 +1301,7 @@ func gcd*[T](x, y: T): T =
     swap x, y
   abs x
 
-when useBuiltins:
+when not defined(noIntrinsicsBitOpts):
   ## this func uses bitwise comparisons from C compilers, which are not always available.
   func gcd*(x, y: SomeInteger): SomeInteger =
     ## Computes the greatest common (positive) divisor of `x` and `y`,