diff --git a/tests/sandwich/config.nims b/tests/sandwich/config.nims
new file mode 100644
index 000000000000..85506fdcadb6
--- /dev/null
+++ b/tests/sandwich/config.nims
@@ -0,0 +1 @@
+switch("experimental", "typeBoundOps")
diff --git a/tests/sandwich/mcontext_thread_local.nim b/tests/sandwich/mcontext_thread_local.nim
new file mode 100644
index 000000000000..718888328d53
--- /dev/null
+++ b/tests/sandwich/mcontext_thread_local.nim
@@ -0,0 +1,15 @@
+# context_thread_local
+import ./mtasks, ./mlistdeques
+
+export mlistdeques            # Exporting the type with destructor doesn't help
+# export tasks               # solution 1. Exporting the inner type
+
+type MagicCompile = object
+  dq: ListDeque[Task]
+
+# var x: MagicCompile        # solution 2. Instantiating the type with destructors
+echo "Success"
+
+type
+  TLContext* = object
+    deque*: ListDeque[Task]
diff --git a/tests/sandwich/mfiles.nim b/tests/sandwich/mfiles.nim
new file mode 100644
index 000000000000..fb36ecf5a920
--- /dev/null
+++ b/tests/sandwich/mfiles.nim
@@ -0,0 +1,11 @@
+import mhandles
+
+type
+  File* = ref object
+    handle: Handle[FD]
+
+proc close*[T: File](f: T) =
+  f.handle.close()
+
+proc newFile*(fd: FD): File =
+  File(handle: initHandle(FD -1))
diff --git a/tests/sandwich/mhandles.nim b/tests/sandwich/mhandles.nim
new file mode 100644
index 000000000000..45b143e2c5da
--- /dev/null
+++ b/tests/sandwich/mhandles.nim
@@ -0,0 +1,19 @@
+type
+  FD* = distinct cint
+
+type
+  AnyFD* = concept fd
+    close(fd)
+
+proc close*(fd: FD) =
+  discard
+
+type
+  Handle*[T: AnyFD] = object
+    fd: T
+
+proc close*[T: AnyFD](h: var Handle[T]) =
+  close h.fd
+
+proc initHandle*[T: AnyFD](fd: T): Handle[T] =
+  Handle[T](fd: fd)
diff --git a/tests/sandwich/mitems.nim b/tests/sandwich/mitems.nim
new file mode 100644
index 000000000000..ea9d7e7246d7
--- /dev/null
+++ b/tests/sandwich/mitems.nim
@@ -0,0 +1,52 @@
+import sets, hashes
+
+type
+  Fruit* = ref object
+    id*: int
+
+  # Generic implementation. This doesn't work
+  EntGroup*[T] = ref object
+    freed*: HashSet[T]
+
+proc hash*(self: Fruit): Hash = hash(self.id)
+
+##
+## VVV The Generic implementation. This doesn't work VVV
+##
+
+proc initEntGroup*[T: Fruit](): EntGroup[T] =
+  result = EntGroup[T]()
+  result.freed = initHashSet[Fruit]()
+  var apple = Fruit(id: 20)
+  result.freed.incl(apple)
+
+proc get*[T: Fruit](fg: EntGroup[T]): T =
+  if len(fg.freed) == 0: return
+  # vvv It errors here 
+  # type mismatch: ([1] fg.freed: HashSet[grouptest.Fruit])
+  for it in fg.freed: 
+    return it
+
+##
+## VVV The Non-Generic implementation works VVV
+##
+type
+  # Non-generic implementation. This works.
+  FruitGroup* = ref object
+    freed*: HashSet[Fruit]
+
+proc initFruitGroup*(): FruitGroup =
+  result = FruitGroup()
+  result.freed = initHashSet[Fruit]()
+  var apple = Fruit(id: 20)
+  result.freed.incl(apple)
+
+proc getNoGeneric*(fg: FruitGroup): Fruit =
+  if len(fg.freed) == 0: return
+  for it in fg.freed:
+    return it
+
+proc `$`*(self: Fruit): string = 
+  # For echo
+  if self == nil: return "Fruit()"
+  return "Fruit(" & $(self.id) & ")"
diff --git a/tests/sandwich/mlistdeques.nim b/tests/sandwich/mlistdeques.nim
new file mode 100644
index 000000000000..ae18ffaa42fa
--- /dev/null
+++ b/tests/sandwich/mlistdeques.nim
@@ -0,0 +1,35 @@
+# listdeques
+
+# needed, type bound ops aren't considered for undeclared procs
+type Placeholder = object
+proc allocate(_: Placeholder) = discard
+proc delete(_: Placeholder) = discard
+
+type
+  StealableTask* = concept task, var mutTask, type T
+    task is ptr
+    task.prev is T
+    task.next is T
+    task.parent is T
+    task.fn is proc (param: pointer) {.nimcall.}
+    allocate(mutTask)
+    delete(task)
+
+  ListDeque*[T: StealableTask] = object
+    head, tail: T
+
+func isEmpty*(dq: ListDeque): bool {.inline.} =
+  discard
+
+func popFirst*[T](dq: var ListDeque[T]): T =
+  discard
+
+proc `=destroy`*[T: StealableTask](dq: var ListDeque[T]) =
+  mixin delete
+  if dq.isEmpty():
+    return
+
+  while (let task = dq.popFirst(); not task.isNil):
+    delete(task)
+
+  delete(dq.head)
diff --git a/tests/sandwich/mobjhash.nim b/tests/sandwich/mobjhash.nim
index 409c31ff9095..ec342f5f6997 100644
--- a/tests/sandwich/mobjhash.nim
+++ b/tests/sandwich/mobjhash.nim
@@ -67,3 +67,14 @@ proc `==`*(a, b: GenericObj4): bool =
 
 proc hash*(a: GenericObj4): Hash =
   !$(hash(a.x) !& hash(a.y))
+
+type
+  GenericRefObj*[T] = ref object
+    x*, y*: T
+    z*: string # to be ignored for equality
+
+proc `==`*[T](a, b: GenericRefObj[T]): bool =
+  a.x == b.x and a.y == b.y
+
+proc hash*[T](a: GenericRefObj[T]): Hash =
+  !$(hash(a.x) !& hash(a.y))
diff --git a/tests/sandwich/mqueuecontainer.nim b/tests/sandwich/mqueuecontainer.nim
new file mode 100644
index 000000000000..3ddbc5a3a94b
--- /dev/null
+++ b/tests/sandwich/mqueuecontainer.nim
@@ -0,0 +1,13 @@
+# original example used queues
+import deques
+
+type
+  QueueContainer*[T] = object
+    q: ref Deque[T]
+
+proc init*[T](c: var QueueContainer[T]) =
+  new(c.q)
+  c.q[] = initDeque[T](64)
+
+proc addToQ*[T](c: var QueueContainer[T], item: T) =
+  c.q[].addLast(item)
diff --git a/tests/sandwich/msetin.nim b/tests/sandwich/msetin.nim
new file mode 100644
index 000000000000..7aa44df6c554
--- /dev/null
+++ b/tests/sandwich/msetin.nim
@@ -0,0 +1,10 @@
+import std/sets
+template foo*[T](a: T) =
+# proc foo*[T](a: T) = # works
+  var s: HashSet[T]
+  # echo contains(s, a) # works
+  let x = a in s # BUG
+  doAssert not x
+  doAssert not (a in s)
+  doAssert a notin s
+when isMainModule: foo(1) # works
diff --git a/tests/sandwich/msetiter1.nim b/tests/sandwich/msetiter1.nim
new file mode 100644
index 000000000000..8049dcf9c848
--- /dev/null
+++ b/tests/sandwich/msetiter1.nim
@@ -0,0 +1,7 @@
+import sets
+
+proc initH*[V]: HashSet[V] =
+  result = initHashSet[V]()
+
+proc foo*[V](h: var HashSet[V], c: seq[V]) =
+  h = h + c.toHashSet()
diff --git a/tests/sandwich/msetiter2.nim b/tests/sandwich/msetiter2.nim
new file mode 100644
index 000000000000..b78175b31089
--- /dev/null
+++ b/tests/sandwich/msetiter2.nim
@@ -0,0 +1,4 @@
+import sets, sequtils
+
+proc dedupe*[T](arr: openArray[T]): seq[T] =
+  arr.toHashSet.toSeq
diff --git a/tests/sandwich/mtasks.nim b/tests/sandwich/mtasks.nim
new file mode 100644
index 000000000000..f585f4f7b4ff
--- /dev/null
+++ b/tests/sandwich/mtasks.nim
@@ -0,0 +1,14 @@
+# tasks.nim
+type
+  Task* = ptr object
+    parent*: Task
+    prev*: Task
+    next*: Task
+    fn*: proc (param: pointer) {.nimcall.}
+
+# StealableTask API
+proc allocate*(task: var Task) =
+  discard
+
+proc delete*(task: Task) =
+  discard
diff --git a/tests/sandwich/tcontext_thread_local.nim b/tests/sandwich/tcontext_thread_local.nim
new file mode 100644
index 000000000000..f015014b8e8f
--- /dev/null
+++ b/tests/sandwich/tcontext_thread_local.nim
@@ -0,0 +1,12 @@
+discard """
+  output: '''
+Success
+'''
+"""
+
+# modified issue #12620, see placeholder procs in mlistdeques
+
+# runtime.nim
+import ./mcontext_thread_local
+
+var localCtx* : TLContext
diff --git a/tests/sandwich/tfilehandles.nim b/tests/sandwich/tfilehandles.nim
new file mode 100644
index 000000000000..3bed18dfae8d
--- /dev/null
+++ b/tests/sandwich/tfilehandles.nim
@@ -0,0 +1,8 @@
+# issue #16755
+
+import mfiles
+from mhandles import FD
+#import handles <- do this and it works
+
+let wr = newFile(FD -1)
+close wr
diff --git a/tests/sandwich/titems.nim b/tests/sandwich/titems.nim
new file mode 100644
index 000000000000..0c3b41026abb
--- /dev/null
+++ b/tests/sandwich/titems.nim
@@ -0,0 +1,13 @@
+# issue #22984
+# import sets # <<-- Uncomment this to make the error go away
+
+import mitems
+
+## The generic implementation
+var grp: EntGroup[Fruit] = initEntGroup[Fruit]()
+doAssert $get(grp) == "Fruit(20)" ## Errors here
+
+
+## This works though (Non-generic)
+var fruitGroup: FruitGroup = initFruitGroup()
+doAssert $getNoGeneric(fruitGroup) == "Fruit(20)"
diff --git a/tests/sandwich/tobjhash.nim b/tests/sandwich/tobjhash.nim
index 6443a99823c3..6c82407e773d 100644
--- a/tests/sandwich/tobjhash.nim
+++ b/tests/sandwich/tobjhash.nim
@@ -1,6 +1,6 @@
 # https://github.com/nim-lang/RFCs/issues/380
 
-from mobjhash import Obj, RefObj, GenericObj1, GenericObj2, GenericObj3, GenericObj4
+from mobjhash import Obj, RefObj, GenericObj1, GenericObj2, GenericObj3, GenericObj4, GenericRefObj
 import tables
 
 block:
@@ -44,3 +44,16 @@ block:
   t[GenericObj4[float](x: 3, y: 4, z: "debug")] = 34
   doAssert t[GenericObj4[float](x: 3, y: 4, z: "ignored")] == 34
   doAssert GenericObj4[float](x: 4, y: 3, z: "debug") notin t
+
+block:
+  var t: Table[GenericRefObj[float], int]
+  t[GenericRefObj[float](x: 3, y: 4, z: "debug")] = 34
+  doAssert t[GenericRefObj[float](x: 3, y: 4, z: "ignored")] == 34
+  doAssert GenericRefObj[float](x: 4, y: 3, z: "debug") notin t
+
+block:
+  type LocalAlias[T] = GenericObj4[T]
+  var t: Table[LocalAlias[float], int]
+  t[LocalAlias[float](x: 3, y: 4, z: "debug")] = 34
+  doAssert t[LocalAlias[float](x: 3, y: 4, z: "ignored")] == 34
+  doAssert LocalAlias[float](x: 4, y: 3, z: "debug") notin t
diff --git a/tests/sandwich/tqueuecontainer.nim b/tests/sandwich/tqueuecontainer.nim
new file mode 100644
index 000000000000..863e44cb7479
--- /dev/null
+++ b/tests/sandwich/tqueuecontainer.nim
@@ -0,0 +1,10 @@
+# issue #4773
+
+import mqueuecontainer
+
+# works if this is uncommented (or if the `queuecontainer` exports `queues`):
+# import queues
+
+var c: QueueContainer[int]
+c.init()
+c.addToQ(1)
diff --git a/tests/sandwich/tsethash.nim b/tests/sandwich/tsethash.nim
new file mode 100644
index 000000000000..ad244d1e66c4
--- /dev/null
+++ b/tests/sandwich/tsethash.nim
@@ -0,0 +1,24 @@
+# issue #14729
+
+import sets, hashes
+
+type
+  Iterable[T] = concept x
+    for value in items(x):
+      type(value) is T
+
+  Foo[T] = object
+    t: T
+
+proc myToSet[T](keys: Iterable[T]): HashSet[T] =
+  for x in items(keys): result.incl(x)
+
+proc hash[T](foo: Foo[T]): Hash =
+  echo "specific hash"
+
+proc `==`[T](lhs, rhs: Foo[T]): bool =
+  echo "specific equals"
+
+let
+  f = Foo[string](t: "test")
+  hs = [f, f].myToSet()
diff --git a/tests/sandwich/tsetin.nim b/tests/sandwich/tsetin.nim
new file mode 100644
index 000000000000..1dd3d2bd9e7c
--- /dev/null
+++ b/tests/sandwich/tsetin.nim
@@ -0,0 +1,4 @@
+# issue #18150
+
+import msetin
+foo(1)
diff --git a/tests/sandwich/tsetiter1.nim b/tests/sandwich/tsetiter1.nim
new file mode 100644
index 000000000000..0fa629b079a5
--- /dev/null
+++ b/tests/sandwich/tsetiter1.nim
@@ -0,0 +1,17 @@
+# comment on issue #11167
+
+import hashes
+
+import msetiter
+
+type
+  Choice = object
+    i: int
+
+proc hash(c: Choice): Hash =
+  result = Hash(c.i)
+
+var h = initH[Choice]()
+let c = @[Choice(i: 1)]
+
+foo(h, c)
diff --git a/tests/sandwich/tsetiter2.nim b/tests/sandwich/tsetiter2.nim
new file mode 100644
index 000000000000..f89eac075f6d
--- /dev/null
+++ b/tests/sandwich/tsetiter2.nim
@@ -0,0 +1,9 @@
+# comment on issue #11167
+
+import msetiter2
+
+let x = dedupe([1, 2, 3])
+doAssert x.len == 3
+doAssert 1 in x
+doAssert 2 in x
+doAssert 3 in x