Workaround for Nim's issue #8044. (#27)

ranges/typedranges.nim

@@ -17,10 +17,19 @@ type
   ByteRange* = Range[byte]
   MutByteRange* = MutRange[byte]
 
+proc isLiteral[T](s: seq[T]): bool {.inline.} =
+  type
+    SeqHeader = object
+      length, reserved: int
+  (cast[ptr SeqHeader](s).reserved and (1 shl (sizeof(int) * 8 - 2))) != 0
+
 proc toImmutableRange[T](a: seq[T]): Range[T] =
   if a.len != 0:
     when rangesGCHoldEnabled:
-      result.gcHold = a
+      if not isLiteral(a):
+        shallowCopy(result.gcHold, a)
+      else:
+        result.gcHold = a
     result.start = addr result.gcHold[0]
     result.mLen = a.len
 

tests/ttypedranges.nim

@@ -71,7 +71,7 @@ suite "Typed ranges":
     var r = s.toRange()
     var r2 = r
     s[0] = 5
-    # check(r[0] == 5) # XXX: Uncomment once nim bug #8044 is fixed
+    check(r[0] == 5)
     r[1] = 10
     check(r2[1] == 10)