permissions-dispatcher/PermissionsDispatcher · error · NoParametersAllowedException

Method '${e.simpleString()}()' must not have any parameters

Error message

Method '${e.simpleString()}()' must not have any parameters

What it means

Thrown by checkMethodParameters in Validators.kt:95 via NoParametersAllowedException. When the expected parameter count for the annotation is zero, the annotated method must declare no parameters; the generated dispatcher constructs the call itself and has nothing to pass.

Source

Thrown at processor/src/main/kotlin/permissions/dispatcher/processor/util/Validators.kt:95

 */
fun checkMethodSignature(items: List<ExecutableElement>) {
    items.forEach {
        // Allow 'void' return type only
        if (it.returnType.kind != TypeKind.VOID) {
            throw WrongReturnTypeException(it)
        }
        // Allow methods without 'throws' declaration only
        if (it.thrownTypes.isNotEmpty()) {
            throw NoThrowsAllowedException(it)
        }
    }
}

fun checkMethodParameters(items: List<ExecutableElement>, numParams: Int, requiredType: TypeMirror? = null) {
    items.forEach {
        val params = it.parameters
        if (numParams == 0 && params.isNotEmpty()) {
            throw NoParametersAllowedException(it)
        }
        if (requiredType == null) {
            return
        }
        if (numParams < params.size) {
            throw WrongParametersException(it, numParams, requiredType)
        }
        // maximum params size is 1
        params.forEach { param ->
            if (!TYPE_UTILS.isSameType(param.asType(), requiredType)) {
                throw WrongParametersException(it, numParams, requiredType)
            }
        }
    }
}

fun <A : Annotation> checkMixPermissionType(items: List<ExecutableElement>, annotationClass: Class<A>) {
    items.forEach {

View on GitHub (pinned to 74b532bf1f)

Solutions

  1. Remove all parameters from the annotated method and access needed values via fields or capture them elsewhere.
  2. Create a parameterless wrapper method that carries the annotation and calls the parameterized helper.
  3. Move to an annotation variant that permits parameters if the library version supports it.

Example fix

// before
@NeedsPermission(Manifest.permission.CAMERA)
fun showCamera(activity: Activity) { ... }

// after
@NeedsPermission(Manifest.permission.CAMERA)
fun showCamera() { /* use fields/this for context */ }
Defensive patterns

Strategy: validation

Validate before calling

@NeedsPermission(Manifest.permission.CAMERA)
fun showCamera() { } // zero parameters for zero-param annotations

Try / catch

try {
    build()
} catch (e: CompilationError) {
    logger.error("Annotated method must not take parameters", e)
}

Prevention

When it happens

Trigger: Annotating a method that takes parameters with an annotation whose numParams is 0, e.g. @NeedsPermission on fun showCamera(context: Context) or any annotated method with parameters where the annotation expects none.

Common situations: Keeping existing method parameters after adding the permission annotation; annotating a helper method with parameters by mistake; misunderstanding that @NeedsPermission methods must be parameterless (use @OnNeverAskAgain-style constants or fields instead).

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

AI-assisted analysis of permissions-dispatcher/PermissionsDispatcher@74b532bf1f (2026-09-08). Data as JSON: /api/errors/15aa5cae8fd26ae7. Report an issue: GitHub.