Feature request: backport KSP's improved method signatures in error messages to apt

[ZacSweers]

(originally from here: #3991 (comment))

The error reported for multiple @Inject constructors in KSP is better, but also has a subtle message difference.

package com.squareup.test

import javax.inject.Inject

class InjectClass @Inject constructor() {
  @Inject constructor(string: String)
}

Kapt error

Type com.squareup.test.InjectClass may only contain one injected constructor. Found: [@Inject com.squareup.test.InjectClass, @Inject com.squareup.test.InjectClass]

KSP error

Type com.squareup.test.InjectClass may only contain one injected constructor. Found: [@Inject com.squareup.test.InjectClass(), @Inject com.squareup.test.InjectClass(String)]

Namely - the KSP error is better in this case as it disambiguates the constructors by their parameters with a fuller description.

A similar change can be seen with error reporting around multiple assisted factories.

package com.squareup.test

import dagger.assisted.Assisted
import dagger.assisted.AssistedFactory
import dagger.assisted.AssistedInject

data class AssistedService @AssistedInject constructor(
  val int: Int,
  @Assisted val string: String
)

interface AssistedServiceFactory1 {
  fun createParent(string: String): AssistedService
}

@AssistedFactory
interface AssistedServiceFactory : AssistedServiceFactory1 {
  fun create(string: String): AssistedService
}

Kapt

The @AssistedFactory-annotated type should contain a single abstract, non-default method but found multiple: [com.squareup.test.AssistedServiceFactory.create, com.squareup.test.AssistedServiceFactory1.createParent]

KSP

The @AssistedFactory-annotated type should contain a single abstract, non-default method but found multiple: [com.squareup.test.AssistedServiceFactory1.createParent(String), com.squareup.test.AssistedServiceFactory.create(String)]

[ZacSweers]

D'oh, nevermind this is something our tests are doing to sanitize the error messages. Apologies for the noise!