typeToString can now show (recursively) resolved type aliases; fixes #8569 #8083 #8570 (#11678)

* nested typeToString
* typeToString: preferResolved
* add test
* fix test
* preferMixed
* fix tests

Author: timotheecour

compiler/semmagic.nim

@@ -141,6 +141,14 @@ proc evalTypeTrait(c: PContext; traitCall: PNode, operand: PType, context: PSym)
     return typeWithSonsResult(tyAnd, @[operand, operand2])
   of "not":
     return typeWithSonsResult(tyNot, @[operand])
+  of "typeToString":
+    var prefer = preferTypeName
+    if traitCall.sons.len >= 2:
+      let preferStr = traitCall.sons[2].strVal
+      prefer = parseEnum[TPreferedDesc](preferStr)
+    result = newStrNode(nkStrLit, operand.typeToString(prefer))
+    result.typ = newType(tyString, context)
+    result.info = traitCall.info
   of "name", "$":
     result = newStrNode(nkStrLit, operand.typeToString(preferTypeName))
     result.typ = newType(tyString, context)