在宏观扩展处访问特定符号的类型时，确认了汇编失败

Question

我必须查看宏中的特定声明并单独检查它们。尝试检查Akka流声明时发生了许多此类错误。

def getType(symbol: Symbol): Type = {
  symbol.typeSignature
}

[error] error while loading SmallSortedMap$Entry, class file '/Users/xxx/.ivy2/cache/com.typesafe.akka/akka-protobuf_2.13/jars/akka-protobuf_2.13-2.5.23.jar(akka/protobuf/SmallSortedMap$Entry.class)' is broken
[error] (class java.util.NoSuchElementException/key not found: K)

以这种方式，似乎在访问特定符号的类型时发生错误。

我想忽略它，隐藏并成功编译

def getType(symbol: Symbol): Option[Type] = {
  Try {
    symbol.typeSignature
  }.getOrElse(None) // Can not capture
}

但是，"班级都被打破了"。不能被"尝试"捕获。例如，具有此符号的包装被排除为黑名单。结果，每次添加依赖性时可能会发生复杂的维护。

  if (symbol.isNotBroken) {
    symbol.typeSignature
  }

有办法解决吗？

尝试

我尝试了Typecheck。

implicit class RichVectorSymbol(value: Vector[Symbol]) {
    def accessible: Vector[Symbol] = {
      value.flatMap { x =>
        scala.util.Try {
          print(s"typecheck ${x.fullName} ")
          c.typecheck(q"${c.parse(x.fullName)}", silent = true)
        } match {
          case Success(r) if r.nonEmpty =>
            println("Success")
            Some(r.symbol)
          case Failure(e) =>
            println("Fail")
            c.warning(c.enclosingPosition, e.getMessage)
            None
          case _ =>
            println("Empty")
            None
        }
      }
    }
  }

结果。

// Success case
typecheck akka.event.jul.Logger Success
typecheck akka.io.dns.CachePolicy Success
typecheck akka.io.dns.DnsSettings Success
// Fail case
typecheck com.fasterxml.jackson.databind.ObjectMapper$2 [error] error while loading ObjectMapper$2, class file '/Users/xxxxx/.ivy2/cache/com.fasterxml.jackson.core/jackson-databind/bundles/jackson-databind-2.9.8.jar(com/fasterxml/jackson/databind/ObjectMapper$2.class)' is broken
[error] (class java.util.NoSuchElementException/key not found: T)
Empty
typecheck akka.protobuf.SmallSortedMap$Entry [error] error while loading SmallSortedMap$Entry, class file '/Users/xxxxx/.ivy2/cache/com.typesafe.akka/akka-protobuf_2.13/jars/akka-protobuf_2.13-2.5.23.jar(akka/protobuf/SmallSortedMap$Entry.class)' is broken
[error] (class java.util.NoSuchElementException/key not found: K)
Empty

这样，我被迫编译错误。样本在这里。https://github.com/giiita/scaladia/blob/master/scaladia-macro/src/main/main/scala/scala/com/phylage/scaladia/scaladia/internal/autternal/autodiextractor.scala

调试

阅读了Scala源代码后，我在内部抛出了一个清晰的IOException，但我无法抓住它，所以我报告了问题，以防万一https://github.com/scala/bug/issues/11611

Answer 1

在宏中您可以尝试

c.typecheck(q"${... some tree ...}", silent = true)

如果树不打字，则此返回空树。

---

这东西似乎是在akka.protobuf.SmallSortedMap$Entry中以美元符号。如果我们用#或.替换$，则错误class file is broken更改为class SmallSortedMap in package protobuf cannot be accessed in package akka.protobuf，这是因为SmallSortedMap具有软件包 - 私有(Java默认(访问。

当我将将字符串参数输入到宏上并使用#或.而不是$。

时，我设法捕获了错误。

  def foo[T]: Unit = macro fooImpl[T]
  def fooImpl[T: c.WeakTypeTag](c: blackbox.Context): c.Tree = {
    import c.universe._
    try {
      println(weakTypeOf[T].typeSymbol.typeSignature)
    } catch {
      case ex: Throwable => println(ex)
    }
    q"()"
  }
  def foo1(tpe: String): Unit = macro foo1Impl
  def foo1Impl(c: blackbox.Context)(tpe: c.Tree): c.Tree = {
    import c.universe._
    val q"${tpeStr: String}" = tpe
    try {
      println(c.typecheck(c.parse(s"val ${c.freshName()}: $tpeStr = ???")))
//      println(c.typecheck(c.parse(tpeStr), mode = c.TYPEmode))
//      println(c.typecheck(c.parse(tpeStr), mode = c.TYPEmode).symbol.companion.typeSignature)
//      println(c.typecheck(c.parse(tpeStr), mode = c.TYPEmode).tpe.typeSymbol.typeSignature)
//      println(c.typecheck(c.parse(tpeStr), mode = c.TYPEmode).tpe)
    } catch {
      case ex: Throwable => println(ex)
    }
    q"()"
  }
  foo[Int]
//  foo[akka.protobuf.SmallSortedMap$Entry]//Error:scalac: error while loading SmallSortedMap$Entry, class file '.ivy2/cache/com.typesafe.akka/akka-protobuf_2.13/jars/akka-protobuf_2.13-2.5.23.jar(akka/protobuf/SmallSortedMap$Entry.class)' is broken(class java.util.NoSuchElementException/key not found: K)
//  foo[akka.protobuf.SmallSortedMap#Entry]//Error: class SmallSortedMap in package protobuf cannot be accessed in package akka.protobuf
//  foo[akka.protobuf.SmallSortedMap.Entry]//Error:class SmallSortedMap in package protobuf cannot be accessed in package akka.protobuf
//  foo1("Int")
//  foo1("akka.protobuf.SmallSortedMap$Entry")//Error:scalac: error while loading SmallSortedMap$Entry, class file '.ivy2/cache/com.typesafe.akka/akka-protobuf_2.13/jars/akka-protobuf_2.13-2.5.23.jar(akka/protobuf/SmallSortedMap$Entry.class)' is broken (class java.util.NoSuchElementException/key not found: K)
  foo1("akka.protobuf.SmallSortedMap#Entry")//Warning:scalac: scala.reflect.macros.TypecheckException: class SmallSortedMap in package protobuf cannot be accessed in package akka.protobuf
  foo1("akka.protobuf.SmallSortedMap.Entry")//Warning:scalac: scala.reflect.macros.TypecheckException: class SmallSortedMap in package protobuf cannot be accessed in package akka.protobuf

否则，当您致电foo[... SomeType ...]时，在扩展Macro foo之前，请使用SomeType。

https://stackoverflow.com/a/56754290/5249621

http://www.scala-archive.org/expand-macros-before-typechecking-its-rguments-arguments-trees-td4641188.html