use nimPreviewSlimSystem, test stdlib category

lib/pure/asyncfutures.nim

@@ -11,6 +11,9 @@ import os, tables, strutils, times, heapqueue, options, deques, cstrutils
 
 import system/stacktraces
 
+when defined(nimPreviewSlimSystem):
+  import std/objectdollar # for StackTraceEntry
+
 # TODO: This shouldn't need to be included, but should ideally be exported.
 type
   CallbackFunc = proc () {.closure, gcsafe.}

lib/system/dollars.nim

@@ -79,6 +79,10 @@ proc `$`*[T: tuple](x: T): string =
   ##   $() == "()"
   tupleObjectDollar(result, x)
 
+when not defined(nimPreviewSlimSystem):
+  import std/objectdollar
+  export objectdollar
+
 proc collectionToString[T](x: T, prefix, separator, suffix: string): string =
   result = prefix
   var firstElement = true

tests/stdlib/toptions.nim

@@ -4,6 +4,9 @@ discard """
 
 import std/[json, options]
 
+when defined(nimPreviewSlimSystem):
+  import std/objectdollar
+
 
 # RefPerson is used to test that overloaded `==` operator is not called by
 # options. It is defined here in the global scope, because otherwise the test

tests/stdlib/tstrformat.nim

@@ -3,6 +3,9 @@
 import genericstrformat
 import std/[strformat, strutils, times, tables, json]
 
+when defined(nimPreviewSlimSystem):
+  import std/objectdollar
+
 proc main() =
   block: # issue #7632
     doAssert works(5) == "formatted  5"