stuff

lib/core/macros.nim

@@ -174,9 +174,6 @@ proc `[]`*(n: NimNode, i: int): NimNode {.magic: "NChild", noSideEffect.}
 proc `[]`*(n: NimNode, i: BackwardsIndex): NimNode = n[n.len - i.int]
   ## get `n`'s `i`'th child.
 
-template `^^`(n: NimNode, i: untyped): untyped =
-  (when i is BackwardsIndex: n.len - int(i) else: int(i))
-
 proc `[]`*[T, U](n: NimNode, x: HSlice[T, U]): seq[NimNode] =
   ## slice operation for NimNode.
   ## returns a seq of child of `n` who inclusive range [n[x.a], n[x.b]].

lib/pure/sugar.nim

@@ -122,12 +122,18 @@ macro `->`*(p, b: untyped): untyped =
 
   result = createProcType(p, b)
 
-type ListComprehension = object
-var lc* {.deprecated.}: ListComprehension
-
-template `|`*(lc: ListComprehension, comp: untyped): untyped {.deprecated.} = lc
-
-macro `[]`*(lc: ListComprehension, comp, typ: untyped): untyped {.deprecated.} =
+template `|`*(a,b: untyped): untyped =
+  ## This template should never expand. At some point in the future it
+  ## will be reved without replacement. When it causes problems,
+  ## unexport with ``import future except `|` ``. It is just a hack to
+  ## get useful error messages for the old `[]` brackeds based list
+  ## comprehension syntax.
+  {.error: "this should never expand. If it does use ``import future except `|` ``.".}
+
+template lc*: untyped =
+  {.error: "list comprehension syntax got changed. replace lc[ x | ... ] with lc( x | ... ) now!".}
+
+macro lc*(comp, typ: untyped): untyped =
   ## List comprehension, returns a sequence. `comp` is the actual list
   ## comprehension, for example ``x | (x <- 1..10, x mod 2 == 0)``. `typ` is
   ## the type that will be stored inside the result seq.