Yet another change to evalOnce

Simplify the checks in order not to break the bootstrap and possibly
cover more cases that were previously ignored.

Fixes nim-lang#8577

lib/pure/collections/sequtils.nim

@@ -635,28 +635,21 @@ template mapIt*(s, typ, op: untyped): untyped =
     result.add(op)
   result
 
-# This is needed in order not to break the bootstrap, the fallback
-# implementation is a "dumb" let that won't work in some cases (eg. when `exp`
-# is an openArray)
-when declared(macros.symKind):
-  macro evalOnce(v, exp: untyped): untyped =
-    expectKind(v, nnkIdent)
-    var val = exp
-
-    result = newStmtList()
-
-    # Not a parameter we can pass as-is, evaluate and store in a temporary
-    # variable
-    if exp.kind != nnkSym or exp.symKind != nskParam:
-      val = genSym()
-      result.add(newLetStmt(val, exp))
-
-    result.add(
-      newProc(name = genSym(nskTemplate, $v), params = [getType(untyped)],
-        body = val, procType = nnkTemplateDef))
-else:
-  macro evalOnce(v, exp: untyped): untyped =
-    result = newLetStmt(v, exp)
+macro evalOnce(v, exp: untyped): untyped =
+  expectKind(v, nnkIdent)
+  var val = exp
+
+  result = newStmtList()
+
+  # If `exp` is not a symbol we evaluate it once here and then use the temporary
+  # symbol as alias
+  if exp.kind != nnkSym:
+    val = genSym()
+    result.add(newLetStmt(val, exp))
+
+  result.add(
+    newProc(name = genSym(nskTemplate, $v), params = [getType(untyped)],
+      body = val, procType = nnkTemplateDef))
 
 template mapIt*(s, op: untyped): untyped =
   ## Convenience template around the ``map`` proc to reduce typing.
@@ -1067,9 +1060,8 @@ when isMainModule:
     doAssert mapLiterals(([1], ("abc"), 2), `$`, nested=true) == (["1"], "abc", "2")
 
   block: # mapIt with openArray
-    when declared(macros.symKind):
-      proc foo(x: openArray[int]): seq[int] = x.mapIt(it + 1)
-      doAssert foo([1,2,3]) == @[2,3,4]
+    proc foo(x: openArray[int]): seq[int] = x.mapIt(it + 1)
+    doAssert foo([1,2,3]) == @[2,3,4]
 
   block: # mapIt with invalid RHS for `let` (#8566)
     type X = enum