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Standard library for the Scala Programming Language
/*
* Scala (https://www.scala-lang.org)
*
* Copyright EPFL and Lightbend, Inc.
*
* Licensed under Apache License 2.0
* (http://www.apache.org/licenses/LICENSE-2.0).
*
* See the NOTICE file distributed with this work for
* additional information regarding copyright ownership.
*/
package scala.annotation
/**
* To customize the error message that's emitted when an implicit of type
* `C[T1,..., TN]` cannot be found, annotate the class `C` with `@implicitNotFound`.
* Assuming `C` has type parameters `X1, ..., XN`, the error message will be the
* result of replacing all occurrences of `\${Xi}` in the string `msg` with the
* string representation of the corresponding type argument `Ti`.
* The annotation is effectively inherited by subtypes if they are not annotated.
*
* The annotation can also be attached to implicit parameters. In this case, `\${Xi}`
* can refer to type parameters in the current scope. The `@implicitNotFound` message
* on the parameter takes precedence over the one on the parameter's type.
*
* {{{
* import scala.annotation.implicitNotFound
*
* @implicitNotFound("Could not find an implicit C[\${T}, \${U}]")
* class C[T, U]
*
* class K[A] {
* def m[B](implicit c: C[List[A], B]) = 0
* def n[B](implicit @implicitNotFound("Specific message for C of list of \${A} and \${B}") c: C[List[A], B]) = 1
* }
*
* object Test {
* val k = new K[Int]
* k.m[String]
* k.n[String]
* }
* }}}
*
* The compiler issues the following error messages:
*
*
* Test.scala:13: error: Could not find an implicit C[List[Int], String]
* k.m[String]
* ^
* Test.scala:14: error: Specific message for C of list of Int and String
* k.n[String]
* ^
*
*/
final class implicitNotFound(msg: String) extends scala.annotation.ConstantAnnotation