fixes #22898; fix #22883 differently (#22900)

fixes #22898
In these cases, the tables/sets are clears or elements are deleted from
them. It's reasonable to suppress warnings because the value is not
accessed anymore, which means it's safe to ignore the warnings.

lib/pure/collections/setimpl.nim

@@ -87,7 +87,9 @@ proc exclImpl[A](s: var HashSet[A], key: A): bool {.inline.} =
       var j = i # The correctness of this depends on (h+1) in nextTry,
       var r = j # though may be adaptable to other simple sequences.
       s.data[i].hcode = 0 # mark current EMPTY
+      {.push warning[UnsafeDefault]:off.}
       reset(s.data[i].key)
+      {.pop.}
       doWhile((i >= r and r > j) or (r > j and j > i) or (j > i and i >= r)):
         i = (i + 1) and msk # increment mod table size
         if isEmpty(s.data[i].hcode): # end of collision cluster; So all done

lib/pure/collections/sets.nim

@@ -382,7 +382,9 @@ proc clear*[A](s: var HashSet[A]) =
   s.counter = 0
   for i in 0 ..< s.data.len:
     s.data[i].hcode = 0
+    {.push warning[UnsafeDefault]:off.}
     reset(s.data[i].key)
+    {.pop.}
 
 
 proc union*[A](s1, s2: HashSet[A]): HashSet[A] =
@@ -816,7 +818,9 @@ proc clear*[A](s: var OrderedSet[A]) =
   for i in 0 ..< s.data.len:
     s.data[i].hcode = 0
     s.data[i].next = 0
+    {.push warning[UnsafeDefault]:off.}
     reset(s.data[i].key)
+    {.pop.}
 
 proc len*[A](s: OrderedSet[A]): int {.inline.} =
   ## Returns the number of elements in `s`.

lib/pure/collections/tableimpl.nim

@@ -119,8 +119,10 @@ template delImplIdx(t, i, makeEmpty, cellEmpty, cellHash) =
         var j = i         # The correctness of this depends on (h+1) in nextTry
         var r = j         # though may be adaptable to other simple sequences.
         makeEmpty(i)                     # mark current EMPTY
+        {.push warning[UnsafeDefault]:off.}
         reset(t.data[i].key)
         reset(t.data[i].val)
+        {.pop.}
         while true:
           i = (i + 1) and msk            # increment mod table size
           if cellEmpty(i):               # end of collision cluster; So all done
@@ -151,8 +153,10 @@ template clearImpl() {.dirty.} =
   for i in 0 ..< t.dataLen:
     when compiles(t.data[i].hcode): # CountTable records don't contain a hcode
       t.data[i].hcode = 0
+    {.push warning[UnsafeDefault]:off.}
     reset(t.data[i].key)
     reset(t.data[i].val)
+    {.pop.}
   t.counter = 0
 
 template ctAnd(a, b): bool =

lib/system.nim

@@ -911,18 +911,14 @@ proc default*[T](_: typedesc[T]): T {.magic: "Default", noSideEffect.} =
 proc reset*[T](obj: var T) {.noSideEffect.} =
   ## Resets an object `obj` to its default value.
   when nimvm:
-    {.push warning[UnsafeDefault]:off.}
     obj = default(typeof(obj))
-    {.pop.}
   else:
     when defined(gcDestructors):
       {.cast(noSideEffect), cast(raises: []), cast(tags: []).}:
         `=destroy`(obj)
         `=wasMoved`(obj)
     else:
-      {.push warning[UnsafeDefault]:off.}
       obj = default(typeof(obj))
-      {.pop.}
 
 proc setLen*[T](s: var seq[T], newlen: Natural) {.
   magic: "SetLengthSeq", noSideEffect, nodestroy.}