5 files changed, 28 insertions, 17 deletions
diff --git a/lib/pure/bitops.nim b/lib/pure/bitops.nim
index b75b0cf9a..57e3c7989 100644
--- a/lib/pure/bitops.nim
+++ b/lib/pure/bitops.nim
@@ -439,7 +439,7 @@ func fastlog2Nim(x: uint64): int {.inline.} =
 # sets.nim cannot import bitops, but bitops can use include
 # system/sets to eliminate code duplication. sets.nim defines
 # countBits32 and countBits64.
-include system/sets
+import system/countbits_impl
 
 template countSetBitsNim(n: uint32): int = countBits32(n)
 template countSetBitsNim(n: uint64): int = countBits64(n)
diff --git a/lib/system.nim b/lib/system.nim
index f0c3da517..574043125 100644
--- a/lib/system.nim
+++ b/lib/system.nim
@@ -2339,6 +2339,7 @@ when notJSnotNims:
   when hostOS != "standalone" and hostOS != "any":
     include "system/dyncalls"
 
+  import system/countbits_impl
   include "system/sets"
 
   when defined(gogc):
diff --git a/lib/system/countbits_impl.nim b/lib/system/countbits_impl.nim
new file mode 100644
index 000000000..6c85612e2
--- /dev/null
+++ b/lib/system/countbits_impl.nim
@@ -0,0 +1,25 @@
+#
+#
+#            Nim's Runtime Library
+#        (c) Copyright 2012 Andreas Rumpf
+#
+#    See the file "copying.txt", included in this
+#    distribution, for details about the copyright.
+#
+
+## Contains the used algorithms for counting bits.
+
+proc countBits32*(n: uint32): int {.compilerproc.} =
+  # generic formula is from: https://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
+  var v = uint32(n)
+  v = v - ((v shr 1'u32) and 0x55555555'u32)
+  v = (v and 0x33333333'u32) + ((v shr 2'u32) and 0x33333333'u32)
+  result = (((v + (v shr 4'u32) and 0xF0F0F0F'u32) * 0x1010101'u32) shr 24'u32).int
+
+proc countBits64*(n: uint64): int {.compilerproc, inline.} =
+  # generic formula is from: https://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
+  var v = uint64(n)
+  v = v - ((v shr 1'u64) and 0x5555555555555555'u64)
+  v = (v and 0x3333333333333333'u64) + ((v shr 2'u64) and 0x3333333333333333'u64)
+  v = (v + (v shr 4'u64) and 0x0F0F0F0F0F0F0F0F'u64)
+  result = ((v * 0x0101010101010101'u64) shr 56'u64).int
diff --git a/lib/system/excpt.nim b/lib/system/excpt.nim
index 8f7e2cbc7..06fa45097 100644
--- a/lib/system/excpt.nim
+++ b/lib/system/excpt.nim
@@ -567,7 +567,7 @@ when defined(cpp) and appType != "lib" and not gotoBasedExceptions and
   type
     StdException {.importcpp: "std::exception", header: "<exception>".} = object
 
-  proc what(ex: StdException): cstring {.importcpp: "((char *)#.what())".}
+  proc what(ex: StdException): cstring {.importcpp: "((char *)#.what())", nodecl.}
 
   proc setTerminate(handler: proc() {.noconv.})
     {.importc: "std::set_terminate", header: "<exception>".}
diff --git a/lib/system/sets.nim b/lib/system/sets.nim
index 42c448848..04e10ba04 100644
--- a/lib/system/sets.nim
+++ b/lib/system/sets.nim
@@ -14,21 +14,6 @@ type
 
 # bitops can't be imported here, therefore the code duplication.
 
-proc countBits32(n: uint32): int {.compilerproc.} =
-  # generic formula is from: https://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
-  var v = uint32(n)
-  v = v - ((v shr 1'u32) and 0x55555555'u32)
-  v = (v and 0x33333333'u32) + ((v shr 2'u32) and 0x33333333'u32)
-  result = (((v + (v shr 4'u32) and 0xF0F0F0F'u32) * 0x1010101'u32) shr 24'u32).int
-
-proc countBits64(n: uint64): int {.compilerproc, inline.} =
-  # generic formula is from: https://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
-  var v = uint64(n)
-  v = v - ((v shr 1'u64) and 0x5555555555555555'u64)
-  v = (v and 0x3333333333333333'u64) + ((v shr 2'u64) and 0x3333333333333333'u64)
-  v = (v + (v shr 4'u64) and 0x0F0F0F0F0F0F0F0F'u64)
-  result = ((v * 0x0101010101010101'u64) shr 56'u64).int
-
 proc cardSet(s: NimSet, len: int): int {.compilerproc, inline.} =
   var i = 0
   result = 0