Bugzilla – Full Text Bug Listing
| Summary: | [1.8][compiler] Missing bridge method in interface results in AbstractMethodError | ||||||
|---|---|---|---|---|---|---|---|
| Product: | [Eclipse Project] JDT | Reporter: | Tobias Grasl <toby> | ||||
| Component: | Core | Assignee: | Srikanth Sankaran <srikanth_sankaran> | ||||
| Status: | VERIFIED FIXED | QA Contact: | |||||
| Severity: | normal | ||||||
| Priority: | P3 | CC: | jarthana, shankhba, srikanth_sankaran, stephan.herrmann, toby | ||||
| Version: | 4.4 | Flags: | jarthana:
review+
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| Target Milestone: | 4.4.1 | ||||||
| Hardware: | Macintosh | ||||||
| OS: | Mac OS X | ||||||
| Whiteboard: | |||||||
| Attachments: |
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I should add, I tested it in Kepler SR2 and Luna. Retargetting to M2, as I don't expect to finish work on these before this week's build(s) Much shorter/simpler test case that still shows the problem:
// --
public class X {
public static void main(String[] args) {
reduce((DoubleInterface) i -> {
return 0;
});
}
static Double reduce(GenericInterface<Double> r) {
return r.reduce(null);
}
}
interface GenericInterface<T> {
T reduce(Integer i);
}
interface DoubleInterface extends GenericInterface<Double> {
default Double reduce(Integer i) {
return 0.0;
}
double reduce(String s);
}
// --
Interface DoubleInterface is missing a bridge to accommodate for the difference in return type erasure. In the case of the anonymous class, this bridge gets emitted into the class. Emitting it into the interface would be the right thing to accommodate for the lambda case. Looking into it. *** Bug 421747 has been marked as a duplicate of this bug. *** Fix and test released here: http://git.eclipse.org/c/jdt/eclipse.jdt.core.git/commit/?id=1412d255f0ba497d3ea8f98ac07c17128ae17670 Jay, I think this should be backported to SR1. Please review. Patch looks safe for SR1 to me. (In reply to Jayaprakash Arthanareeswaran from comment #8) > Patch looks safe for SR1 to me. Tests ran fine locally. Will release after looking at tonight's I build result. Released in R4_4_maintenance. Verified for 4.4.1 with build M20140827-0800. and Verified for 4.5 M2 with build N20140827-2000. |
Created attachment 243774 [details] Code that demonstrates the bug In the attached sample I have a Generic Interface which accepts generic objects, and a specialised subinterface which accepts specialised objects, and provides a default method for the generic interface's method, which delegates to the specialised implementation. If I implement the specialised method in an anonymous class, and pass it to some code that calls the generic method, then the code correctly executes and passed through to the specialised method. However, if, rather than implementing the anonymous class, I use a lambda expression, the code compiles fine, but at runtime I get an AbstractMethodError "java.lang.AbstractMethodError: Method LambdaBugDemo$$Lambda$1.reduce(Ljava/util/Iterator;)Ljava/lang/Object". Apparently, the default method is not picked up. This code compiles and runs fine on Oracle JDK 1.8_05 for OsX. It compiles fine in eclipse, but the generated code throughs the error as specified. The attached java file contains a full demonstration of the problem.