Issue 752 in google-guice: Guice.createInjector enforces bindings that become unused by Modules.override

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Status: New
Owner: ----

New issue 752 by zorze...@gmail.com: Guice.createInjector enforces bindings
that become unused by Modules.override
http://code.google.com/p/google-guice/issues/detail?id=752

See test case below. I have a module Foo with an @Provides (buildInt)
method, and I Modules.override it with another Bar module that redeclares
the same binding. Therefore, Foo.buildInt is a dead method -- it will never
be executed. But, when the injector is created, it throws, because that
method needs a param that is not bound.

The way I came across this issue is that I precisely wanted to override a
binding in my test because that binding needs a class that is not available
on these tests.

********************

import com.google.inject.AbstractModule;
import com.google.inject.CreationException;
import com.google.inject.Guice;
import com.google.inject.Injector;
import com.google.inject.Module;
import com.google.inject.Provides;
import com.google.inject.util.Modules;

import junit.framework.TestCase;

import org.junit.Assert;

import java.util.regex.Pattern;

public class OverrideBugTestCase extends TestCase {

private static final class Foo extends AbstractModule {

@Override
protected void configure() {}

@Provides
public static Integer buildInt(Pattern foo) {
return 1;
}
}

private static final class Bar extends AbstractModule {

@Override
protected void configure() {}

@Provides
public static Integer buildInt() {
return 2;
}
}

public void testOverride() throws Exception {
Module foo = new Foo();
Module bar = Modules.override(foo).with(new Bar());

// This line is throwing! Even though Bar overrode Foo's Integer
binding,
// Guice still tries to fullfil all bindings needed by Foo.buildInt,
which
// include an unbound Pattern.
Injector barInjector = Guice.createInjector(bar);

Assert.assertEquals((Integer)2, barInjector.getInstance(Integer.class));

try {
Guice.createInjector(foo).getInstance(Integer.class);
fail();
} catch (CreationException e) {}
}
}


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Updates:
Status: WontFix

Comment #1 on issue 752 by sberlin: Guice.createInjector enforces bindings

that become unused by Modules.override
http://code.google.com/p/google-guice/issues/detail?id=752

This is happening because of the way @Provides methods are implemented --
we call binder.getProvider(Class) for each arg of an @Provides method when
doing the binding. Unfortunately there's no built-in way to know "what
caused this binding", nor is there any graph analysis to know what's dead
or not. So unfortunately there's really no way of fixing this until we do
full graph analysis (and record who "wanted" each binding).

I'm gonna close this one as WontFix 'cause there's really no way I can see
this happening.. but if you or anyone can dig in and supply a patch that
makes this happen, awesome.