semtypinst: don't wrap type nodes from expressions in static[T] (#18860)

compiler/semtypinst.nim

@@ -548,7 +548,7 @@ proc replaceTypeVarsTAux(cl: var TReplTypeVars, t: PType): PType =
       result = n.typ.skipTypes({tyTypeDesc})
       # result = n.typ.base
     else:
-      if n.typ.kind != tyStatic:
+      if n.typ.kind != tyStatic and n.kind != nkType:
         # XXX: In the future, semConstExpr should
         # return tyStatic values to let anyone make
         # use of this knowledge. The patching here

tests/generics/t18859.nim

@@ -0,0 +1,17 @@
+import macros
+
+macro symFromDesc(T: typedesc): untyped =
+  let typ = getType(T)
+  typ[1]
+
+template produceType(T: typedesc): untyped =
+  type
+    XT = object
+      x: symFromDesc(T)
+
+  XT
+
+type
+  X[T] = produceType(T)
+
+var x: X[int]