Inherited package private types not found for injection

[benalexau]

Package-level access visibility is frequently used to improve encapsulation and guide users toward a public API. It is still useful to have Avaje construct these package-protected types and inject them into other types in the same package where requested. At present, Avaje raises an error if this pattern is attempted. Consider:

package com.foo;

interface Adder {
  int add(int a, int b);
}

package com.foo;

import jakarta.inject.Singleton;

@Singleton
class AdderImpl implements Adder {

  @Override
  public int add(int a, int b) {
    return a + b;
  }
}

package com.foo;

import jakarta.inject.Singleton;

@Singleton
public class Calculator {
  private final Adder adder;

  public Calculator(Adder adder) {
    this.adder = adder;
  }

  public int sum(int a, int b) {
    return adder.add(a, b);
  }
}

package com.foo;

import static org.assertj.core.api.Assertions.*;

import io.avaje.inject.test.InjectTest;
import jakarta.inject.Inject;
import org.junit.jupiter.api.Test;

@InjectTest
final class CalculatorTest {

  @Inject Calculator calculator;

  @Test
  void verify() {
    assertThat(calculator.sum(40, 2)).isEqualTo(42);
  }
}

This reports a compilation failure:

/project-path/src/main/java/com/foo/Calculator.java:[6,8] No dependency provided for com.foo.Adder on com.foo.Calculator
[ERROR] Dependencies [com.foo.Adder] are not provided - there are no @Singleton, @Component, @Factory/@Bean that currently provide this type. If this is an external dependency consider specifying via @External

It would be good if Avaje allowed package-protected types to be eligible for injection.

[SentryMan]

I see

[SentryMan]

It's really only a problem for types extending package private types, as package private supertypes are not registered as provided. That is, if the interface was not package private your code would work.

Do you actually require the interfaces to be package private? Isn't the point of having interfaces like that is so they would be exposed as public api?

[benalexau]

Isn't the point of having interfaces like that is so they would be exposed as public api?

I use interfaces extensively to define contracts for custom annotation processors that implement repositories, messaging system adapters etc. It is desirable to prevent their use outside the declaring package. I agree that a public interface and package-protected implementation would be a reasonable approach though.

[SentryMan]

I see