better initialization patterns for seminst (#22456)

* better initialization patterns for seminst

* Update compiler/seminst.nim

* Update compiler/seminst.nim

compiler/seminst.nim

@@ -29,11 +29,7 @@ proc addObjFieldsToLocalScope(c: PContext; n: PNode) =
  else: discard
 
 proc pushProcCon*(c: PContext; owner: PSym) =
- var x: PProcCon
- new(x)
- x.owner = owner
- x.next = c.p
- c.p = x
+ c.p = PProcCon(owner: owner, next: c.p)
 
 const
  errCannotInstantiateX = "cannot instantiate: '$1'"
@@ -172,18 +168,13 @@ proc instGenericContainer(c: PContext, info: TLineInfo, header: PType,
  allowMetaTypes = false): PType =
  internalAssert c.config, header.kind == tyGenericInvocation
 
- var
- cl: TReplTypeVars = default(TReplTypeVars)
+ var cl: TReplTypeVars = TReplTypeVars(symMap: initIdTable(),
+ localCache: initIdTable(), typeMap: LayeredIdTable(),
+ info: info, c: c, allowMetaTypes: allowMetaTypes
+ )
 
- cl.symMap = initIdTable()
- cl.localCache = initIdTable()
- cl.typeMap = LayeredIdTable()
  cl.typeMap.topLayer = initIdTable()
 
- cl.info = info
- cl.c = c
- cl.allowMetaTypes = allowMetaTypes
-
  # We must add all generic params in scope, because the generic body
  # may include tyFromExpr nodes depending on these generic params.
  # XXX: This looks quite similar to the code in matchUserTypeClass,