CODEWITHSUNDEEP
scalasbtwarningscompiler-warnings
tomek.xyz
tomek.xyz

Reputation: 139

How to configure `sbt` to not display warnings "Warning private default argument in object * is never used"

I have a scala compiler 2.12.11 and compiler prints some warnings, like:
private default argument in class SomeClass is never used while as it is used.

I have seen a Scala 2.12.2 emits a ton of useless "Warning: parameter value ... in method ... is never used" warnings. How to get rid of them? however it doesn't help me, as it is not possible to negate params.
Can you help me to surpress this warning, however saving another unused warnings? Currently, I have -Xlint option.

Upvotes: 0

Views: 1046

Answers (1)

Mateusz Kubuszok
Mateusz Kubuszok

Reputation: 27535

Instead of -Xlint which is a batch, you can turn on specific options manually. For instant in 2.13 I can print available options like this:

scalac -Xlint:help
Enable recommended warnings
  adapted-args            An argument list was modified to match the receiver.
  nullary-unit            `def f: Unit` looks like an accessor; add parens to look side-effecting.
  inaccessible            Warn about inaccessible types in method signatures.
  infer-any               A type argument was inferred as Any.
  missing-interpolator    A string literal appears to be missing an interpolator id.
  doc-detached            When running scaladoc, warn if a doc comment is discarded.
  private-shadow          A private field (or class parameter) shadows a superclass field.
  type-parameter-shadow   A local type parameter shadows a type already in scope.
  poly-implicit-overload  Parameterized overloaded implicit methods are not visible as view bounds.
  option-implicit         Option.apply used an implicit view.
  delayedinit-select      Selecting member of DelayedInit.
  package-object-classes  Class or object defined in package object.
  stars-align             In a pattern, a sequence wildcard `_*` should match all of a repeated parameter.
  strict-unsealed-patmat  Pattern match on an unsealed class without a catch-all.
  constant                Evaluation of a constant arithmetic expression resulted in an error.
  unused                  Enable -Wunused:imports,privates,locals,implicits,nowarn.
  nonlocal-return         A return statement used an exception for flow control.
  implicit-not-found      Check @implicitNotFound and @implicitAmbiguous messages.
  serial                  @SerialVersionUID on traits and non-serializable classes.
  valpattern              Enable pattern checks in val definitions.
  eta-zero                Usage `f` of parameterless `def f()` resulted in eta-expansion, not empty application `f()`.
  eta-sam                 The Java-defined target interface for eta-expansion was not annotated @FunctionalInterface.
  deprecation             Enable -deprecation and also check @deprecated annotations.
  byname-implicit         Block adapted by implicit with by-name parameter.
  recurse-with-default    Recursive call used default argument.
  unit-special            Warn for specialization of Unit in parameter position.
  multiarg-infix          Infix operator was defined or used with multiarg operand.
  implicit-recursion      Implicit resolves to an enclosing definition.
Default: All choices are enabled by default.

so I could e.g. enable -Xlint:inaccessible -Xlint:adapted-args -Wunused:privates,locales or whatever I want instead of everything. For 2.12 this list would be different. (You can also check scalac -X, scalac -Y and scalac -W).

An alternative is to enable warnings and suppress them when you "breaking" something consciously. For unused you have @scala.annotation.unused, for other warnings in 2.12 and before there is silencer plugin and since 2.13 there is @scala.annotation.nowarn annotation.

Upvotes: 1

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