Overloaded Java method selection doesn't see all possible coercions
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Key: JRUBY-5476
URL: http://jira.codehaus.org/browse/JRUBY-5476
Project: JRuby
Issue Type: Bug
Components: Java Integration
Affects Versions: JRuby 1.6RC2
Reporter: Charles Oliver Nutter
The case I ran into was from "madmarco" on IRC. In his case, he was trying to
reify a Ruby class and pass it to a method that accepts a java.lang.Class.
It works for a simple case:
{noformat}
~/projects/jruby ➔ mirahc -e "def foo(c:Class); puts
c.getMethods.length; end"
~/projects/jruby ➔ jruby -rjruby/core_ext -rjava -e 'class Foo; end;
Foo.become_java!; Java::DashE.foo(Foo)'
203
~/projects/jruby ➔ javap DashE
Compiled from DashE
public class DashE extends java.lang.Object{
public static void main(java.lang.String[]);
public static java.io.PrintStream foo(java.lang.Class);
public DashE();
}
{noformat}
But fails when there's overloads of the method/constructor in question:
{noformat}
~/projects/jruby ➔ mirahc -e "def foo(c:Class); puts
c.getMethods.length; end; def foo(a:String, c:Class); end"
~/projects/jruby ➔ javap DashE
Compiled from DashE
public class DashE extends java.lang.Object{
public static void main(java.lang.String[]);
public static java.io.PrintStream foo(java.lang.Class);
public static java.lang.Object foo(java.lang.String, java.lang.Class);
public DashE();
}
~/projects/jruby ➔ jruby -rjruby/core_ext -rjava -e 'class Foo; end;
Foo.become_java!; Java::DashE.foo(Foo)'
-e:1:in `(root)': no foo with arguments matching [class org.jruby.RubyClass] on
object Java::Default::DashE (NameError)
{noformat}
The problem here is that our overload selection does not know about what toJava
supports on various classes. So in this case, it doesn't know that toJava
*would* return an appropriate java.lang.Class object, and so it refuses to
select that overload.
The workaround for now is to explicitly coerce the object to the appropriate
type, such as using to_java. In this case, calling the method with
Foo.to_java(:class) works correctly.
The fix is that we need overload selection to know about each argument's
supported types.
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