Merge pull request #52 from alaviss/fix/issue-51

Fixes for 0.1.5

union.nim

@@ -335,8 +335,9 @@ template union*(T: untyped): untyped =
   ## The typeclass may contain other typeclasses, or other unions.
   ##
   ## If the typeclass contain one unique type, then that unique type will be returned.
-  type TImpl {.gensym.} = T
-  unionize(TImpl, T)
+  block:
+    type TImpl = T
+    unionize(TImpl, T)
 
 proc unionize(T, info: NimNode): NimNode =
   ## The actual union type builder

union.nimble

@@ -1,6 +1,6 @@
 # Package
 
-version       = "0.1.4"
+version       = "0.1.5"
 author        = "Leorize"
 description   = "Anonymous unions in Nim"
 license       = "MIT"

union/uniontraits.nim

@@ -24,6 +24,9 @@ type
     ## Internally all Unions are a case object, dispatched via a compile-time
     ## generated enum.
 
+  UnionInst = Union[void]
+    ## The instance of `Union` used as parent for union types.
+
 converter toNimNode(u: UnionTy): NimNode = NimNode(u)
   ## Allow us to manipulate UnionTy in here.
   ##
@@ -63,13 +66,10 @@ func newUnionType*(enumType: NimNode): UnionTy =
   result = UnionTy:
     nnkObjectTy.newTree(
       newEmptyNode(), # The generics portion, we don't have it
-      # Inherit from `Union[void]` to allow unions to be matched by a
+      # Inherit from an instance of `Union` to allow unions to be matched by a
       # T: Union constraint
       nnkOfInherit.newTree(
-        nnkBracketExpr.newTree(
-          bindSym"Union",
-          bindSym"void"
-        )
+        bindSym"UnionInst"
       ),
       # The list of fields
       nnkRecList.newTree(
@@ -87,8 +87,11 @@ proc getUnionType*(n: NimNode): UnionTy =
   ## Returns `nil` if `n` is not an union.
   let typ = getTypeSkip(n)
   if typ.kind == nnkObjectTy:
-    # Verify that `n` inherits from Union.
-    if typ.inherits.sameType(bindSym"Union"):
+    # Verify that `n` inherits from UnionInst.
+    if typ.inherits.sameType(bindSym"UnionInst"):
+      UnionTy(typ)
+    # For Nim before PR 22642
+    elif typ.inherits.sameType(bindSym"Union"):
       UnionTy(typ)
     else:
       UnionTy(nil)