Description Jack Smith 2020-05-07 06:29:46 EDT

Created attachment 282736 [details]
Minimal example to demonstrate issue.

The following example raises an IllegalArgumentException when compiled under Eclipse and NonVisibleLambda is run. No IllegalArgumentException is raised when compiled with javac and run.

stack trace:
Exception in thread "main" java.lang.BootstrapMethodError: java.lang.IllegalAccessError: tried to access class some.other.pkg.AbstractFoo$AbstractFooBuilder from class some.pkg.NonVisibleLambda
	at some.pkg.NonVisibleLambda.main(NonVisibleLambda.java:13)
Caused by: java.lang.IllegalAccessError: tried to access class some.other.pkg.AbstractFoo$AbstractFooBuilder from class some.pkg.NonVisibleLambda
	... 1 more

-------------------------------
some/pkg/NonVisibleLambda.java
-------------------------------
package some.pkg;

import java.util.stream.Stream;

import some.other.pkg.ShinyFoo;
import some.other.pkg.ShinyFoo.ShinyFooBuilder;

public class NonVisibleLambda
{
    public static void main( final String[] args )
    {
        final ShinyFooBuilder builder = ShinyFoo.builder();
        Stream.of( "hello", "hola", "hallo", "bonjour" ).forEach( builder::bar );
        builder.baz( "world" ).build().foo();
    }
}
-------------------------------
some/other/pkg/AbstractFoo.java
-------------------------------
package some.other.pkg;

import java.util.ArrayList;
import java.util.List;

abstract class AbstractFoo
{
    protected final List<String> bars;

    protected AbstractFoo( final AbstractFooBuilder<?, ?> builder )
    {
        bars = builder.bars;
    }

    abstract void foo();

    static abstract class AbstractFooBuilder<T extends AbstractFoo, B extends AbstractFooBuilder<T, B>>
    {
        private final List<String> bars = new ArrayList<>();;

        public B bar( final String bar )
        {
            bars.add( bar );
            return getThis();
        }

        protected B getThis()
        {
            return (B)this;
        }

        protected abstract T build();
    }
}
-------------------------------
some/other/pkg/ShinyFoo.java
-------------------------------
package some.other.pkg;

import static java.util.stream.Collectors.joining;

public class ShinyFoo extends AbstractFoo
{
    public static ShinyFooBuilder builder()
    {
        return new ShinyFooBuilder();
    }

    private final String baz;

    private ShinyFoo( final ShinyFooBuilder builder )
    {
        super( builder );
        baz = builder.baz;
    }

    @Override
    public void foo()
    {
        System.out.println( bars.stream().collect( joining( ", ") ) + ", " + baz + "!" );
    }

    public static class ShinyFooBuilder extends AbstractFooBuilder<ShinyFoo, ShinyFooBuilder>
    {
        private String baz;

        public ShinyFooBuilder baz( final String baz )
        {
            this.baz = baz;
            return getThis();
        }

        @Override
        public ShinyFoo build()
        {
            return new ShinyFoo( this );
        }
    }
}

If the method being referenced by method refernce (i.e. some/other/pkg/AbstractFoo.AbstractFooBuilder.bar(...)):

public B bar( final String bar )
{
    bars.add( bar );
    return getThis();
}

is changed to

public void bar( final String bar )
{
    bars.add( bar );
}

i.e. no return type, then no exception is raised.

Changing the method reference to an expression i.e. 
builder::foo to 
s -> builder.foo( s ) 
is the workaround at present.

Version information:

Eclipse IDE for Java Developers
Version: 2020-03 (4.15.0)
Build id: 20200313-1211

Eclipse Java Development Tools
Version: 3.18.300.v20200305-0155
Build id: I20200305-0155

openjdk version "1.8.0_252"
OpenJDK Runtime Environment (AdoptOpenJDK)(build 1.8.0_252-b09)
OpenJDK 64-Bit Server VM (AdoptOpenJDK)(build 25.252-b09, mixed mode)

javac 1.8.0_252

Windows 10 64-bit
Microsoft Windows
Verion 1909 (OS Build 18363.657)

n.b. this it NOT a duplicate of https://bugs.eclipse.org/bugs/show_bug.cgi?id=480930 but looks very similar. Bug 480930 had no return type on the method reference - this one does.