Complitation error of "recursive value x needs type" may occur if named parameter used #5434

scabug · 2012-02-05T11:02:40Z

See: http://stackoverflow.com/questions/9148339/why-this-scala-code-reports-compilation-error-recursive-value-x-needs-type

Details:

The scala code is simple:

case class X(id: Option[String] = None, username: Option[String])

object X {
  def create(x: X): X = {
    x.copy(id = Some("111"))
  }
}

class Test {
   def test() {
    val x = X.create(X(
      username = Some("Hello, world!")))

    val id = x.id.get  // !!! reports: recursive value x needs type
  }
}

Please note the line:

val id = x.id.get

Why it reports recursive value x needs type?

If I change the variable name, as:

    val dd = x.id.get

It will be OK.

scabug · 2012-02-05T11:02:40Z

Imported From: https://issues.scala-lang.org/browse/SI-5434?orig=1
Reporter: Freewind (freewind)
Affected Versions: 2.9.1
Duplicates #5091

scabug · 2015-01-30T14:19:36Z

@lrytz said:
minimized:

class Test {
  def foo(id: Int = 1, p: Int)

  def test() {
    val x = foo(p = 2)
    val id = x + 1
  }
}

gives

A.scala:7: error: recursive value x needs type
    val id = x + 1  // !!! reports: recursive value x needs type
             ^
A.scala:5: warning: type-checking the invocation of method foo checks if the named argument expression 'id = ...' is a valid assignment
in the current scope. The resulting type inference error (see above) can be fixed by providing an explicit type in the local definition for id.
    val x = foo(p = 2)
            ^
one warning found
one error found

Unfortunately, the warning message doesn't say that the "named argument expression 'id = ...'" was generated by the compiler and is not visible in the source code.

scabug closed this as completed Feb 5, 2012

scabug added the duplicate label Apr 7, 2017

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Complitation error of "recursive value x needs type" may occur if named parameter used #5434

Complitation error of "recursive value x needs type" may occur if named parameter used #5434

scabug commented Feb 5, 2012 •

edited by retronym

scabug commented Feb 5, 2012

scabug commented Jan 30, 2015

Complitation error of "recursive value x needs type" may occur if named parameter used #5434

Complitation error of "recursive value x needs type" may occur if named parameter used #5434

Comments

scabug commented Feb 5, 2012 • edited by retronym

scabug commented Feb 5, 2012

scabug commented Jan 30, 2015

scabug commented Feb 5, 2012 •

edited by retronym