fixes booting warnings (#21583)

compiler/semtypes.nim

@@ -803,8 +803,7 @@ proc semRecordNodeAux(c: PContext, n: PNode, check: var IntSet, pos: var int,
       else: illFormedAst(n, c.config)
       if c.inGenericContext > 0:
         # use a new check intset here for each branch:
-        var newCheck: IntSet
-        assign(newCheck, check)
+        var newCheck: IntSet = check
         var newPos = pos
         var newf = newNodeI(nkRecList, n.info)
         semRecordNodeAux(c, it[idx], newCheck, newPos, newf, rectype, hasCaseFields)

compiler/sighashes.nim

@@ -9,11 +9,10 @@
 
 ## Computes hash values for routine (proc, method etc) signatures.
 
-import ast, tables, ropes, md5, modulegraphs, options, msgs, packages, pathutils
+import ast, tables, ropes, md5, modulegraphs, options, msgs, pathutils
 from hashes import Hash
 import types
 
-import std/os
 
 when defined(nimPreviewSlimSystem):
   import std/assertions

compiler/types.nim

@@ -1686,7 +1686,7 @@ proc isTupleRecursive(t: PType, cycleDetector: var IntSet): bool =
   of tyTuple:
     var cycleDetectorCopy: IntSet
     for i in 0..<t.len:
-      assign(cycleDetectorCopy, cycleDetector)
+      cycleDetectorCopy = cycleDetector
       if isTupleRecursive(t[i], cycleDetectorCopy):
         return true
   of tyAlias, tyRef, tyPtr, tyGenericInst, tyVar, tyLent, tySink,

compiler/vmops.nim

@@ -38,7 +38,6 @@ when defined(nimPreviewSlimSystem):
 else:
   from std/formatfloat import addFloatRoundtrip, addFloatSprintf
 
-from std/strutils import formatBiggestFloat, FloatFormatMode
 
 # There are some useful procs in vmconv.
 import vmconv, vmmarshal