fixes #11747

compiler/semexprs.nim

@@ -1414,6 +1414,9 @@ proc semDeref(c: PContext, n: PNode): PNode =
   var t = skipTypes(n.sons[0].typ, {tyGenericInst, tyVar, tyLent, tyAlias, tySink, tyOwned})
   case t.kind
   of tyRef, tyPtr: n.typ = t.lastSon
+  of tyTypeDesc:
+    # typeof(x[]) is still a typedesc:
+    n.typ = makeTypeDesc(c, t.lastSon.lastSon)
   else: result = nil
   #GlobalError(n.sons[0].info, errCircumNeedsPointer)
 

tests/metatype/ttypedesc3.nim

@@ -5,6 +5,7 @@ proc Child
 method Base
 yield Base
 yield Child
+12
 '''
 """
 
@@ -27,3 +28,16 @@ when false:
 
 for s in Base.it: echo s
 for s in Child.it: echo s #<- bug #2662
+
+
+# bug #11747
+
+type
+  MyType = object
+    a: int32
+    b: int32
+    c: int32
+
+  MyRefType = ref MyType
+
+echo sizeof(MyRefType[])