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Unexpected compilation failure: "not found: value <value name>" #9171

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scabug opened this issue Feb 22, 2015 · 3 comments
Closed

Unexpected compilation failure: "not found: value <value name>" #9171

scabug opened this issue Feb 22, 2015 · 3 comments

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@scabug
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scabug commented Feb 22, 2015

I have encountered this problem when using scopt 3.3.0.
Here is the minimal test case that reproduces consistently.

object FailToCompileApp extends App {
  case class Options(window: Int = 30)
  val parser = new scopt.OptionParser[Options]("FailToCompileApp") {
    opt[Int]('w', "window") action { (w, options) =>
      options.copy(window = w)
    }
  }

  val options = parser.parse(args, Options()).get
  val window = options.window
}
[info] Compiling 1 Scala source to /Users/alexbool/Documents/IdeaProjects/myproject/target/scala-2.11/classes...
[error] /Users/alexbool/Documents/IdeaProjects/myproject/src/main/scala/me/alexbool/myproject/apps/FailToCompileApp.scala:7: not found: value w
[error]       options.copy(window = w)
[error]                             ^
[error] one error found
[error] (compile:compile) Compilation failed

The most exciting thing is when I remove the last line ("val window = options.window"), it compiles OK.

@scabug
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scabug commented Feb 22, 2015

Imported From: https://issues.scala-lang.org/browse/SI-9171?orig=1
Reporter: Alexander Bulaev (alexbool)
Affected Versions: 2.11.5
See #6391

@scabug
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scabug commented Feb 22, 2015

@som-snytt said (edited on Feb 22, 2015 10:56:21 PM UTC):
Workaround is to annotate the window field, val window: Int = options.window.

A variant on "is it an assignment or a named arg?"

Edit: with -Ytyper-debug, error unless options also has explicit type.

|    |    |-- parser.parse(args, Options()) EXPRmode-POLYmode-QUALmode (site: value options  in Test) 
|    |    |    |-- parser.parse BYVALmode-EXPRmode-FUNmode-POLYmode (silent: value options  in Test) 
|    |    |    |    |-- parser EXPRmode-POLYmode-QUALmode (silent: value options  in Test) 
|    |    |    |    |    \-> trial.Test.parser.type (with underlying type scopt.OptionParser[trial.Options])
|    |    |    |    \-> (args: Seq[String], init: trial.Options)Option[trial.Options] <and> (args: Seq[String])(implicit ev: scopt.Zero[trial.Options])Boolean
|    |    |    caught scala.reflect.internal.Symbols$CyclicReference: illegal cyclic reference involving value options: while typing parser.parse(args, Options())

error] /home/apm/tmp/trial/src/main/scala/Trial.scala:15: recursive value options needs type
[error]   val options = parser.parse(args, Options()).get
[error]                             ^

@hrhino
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hrhino commented Feb 7, 2018

Fixed / obviated in 2.13.0-M3 (presumably by scala/scala#6092).

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