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Example: --- Java ---- public interface MyList { <T> T toArray(T a); } ----------- --- Xtend --- class bar extends MyList implements MyIf{ override <T> toArray(T a) { } } ------------ the Xtend method is flagged with two errors: --- - Name clash: The method toArray(T) of type bar has the same erasure as toArray (T) of type MyList but does not override it. - Function does not override any function --- I'd expect no errors.
Moritz, could you please update your example and reopen the ticket if necessary? class bar extends MyList seems bogus to me since MyList is an interface in your example. I tried this one instead and it compiled without errors: Java: public interface MyIntf { <T> T toArray(T a); } Xtend: class bar implements MyIntf { override <T> toArray(T a) { throw new UnsupportedOperationException("Auto-generated function stub") } }
I tried the following, and the error still exits: 1. create a new Xtend class that implements java.util.list<Object> 2. use the quick fix to add the unimplementd methods. get the following errors: - Duplicate method toArray(T[]) in type Foo - The method toArray(T[]) : void of type Foo must override a superclass method. the method override <T> toArray(T[] arg0) is indeed create twice. If I delete one of them, these errors remain: - Name clash: The method toArray(T[]) of type Foo has the same erasure as toArray(T[]) of type List but does not override it. - The method toArray(T[]) : void of type Foo must override a superclass method. - Name clash: The method toArray(T[]) of type Foo has the same erasure as toArray(T[]) of type Collection but does not override it.
I thin the typeParameter is the problem. After some debugging I can see that EcoreUtil.equals(overridingType, overriddenType) in org.eclipse.xtext.common.types.util.FeatureOverridesService.isSameArgumentTypes(JvmOperation, JvmOperation, ITypeArgumentContext) is answering with false because the Type T has different declarators List and the overwriting type. The rest of the implementation of org.eclipse.xtext.common.types.util.FeatureOverridesService.isSameArgumentTypes(JvmOperation, JvmOperation, ITypeArgumentContext) cares only for JvmTypeParameter and not for JvmArrayType.
Created attachment 215000 [details] Potential fix This patch solves the problem but it feels hacky and I am not sure if there are sideeffects. Any opinions?
Created attachment 215001 [details] Missing guard
Created attachment 215002 [details] Potential fix
Created attachment 215003 [details] Potential fix
Created attachment 215004 [details] Potential fix But still feels hacky.
I doubt that this'll fix the issue since we get the same problems with this example: import java.util.List abstract class A<T> { def <T1> T1[] getValue1(List<T1> t) def <T2> T2[] getValue2(T2[] t) def <T3> List<T3> getValue3(List<T3> t) } abstract class B<T> extends A<T> { override <V> V[] getValue1(List<V> v) {} } abstract class C<T> extends A<T> { override <V> V[] getValue2(V[] t) {} } abstract class D<T> extends A<T> { override <V> List<V> getValue3(List<V> t) {} }
Right. But EcoreUtil.equals will not solve the problem.
Created attachment 215009 [details] patch This patch potentially solves the problem discussed in this bug but after all methods are accepted as overriding methods the returnType is not valid. I think this is another bug caused by the same issue -> TypeParameters I think. package foo.bar import java.util.List abstract class A<T> { def <T1> T1[] getValue1(List<T1> t) def <T2> T2[] getValue2(T2[] t) def <T3> List<T3> getValue3(List<T3> t) } abstract class B<T> extends A<T> { override <V> V[] getValue1(List<V> v) {} } abstract class C<T> extends A<T> { override <V> V[] getValue2(V[] t) {} } abstract class D<T> extends A<T> { override <V> List<V> getValue3(List<V> t) {} } Errors: The return type is incompatible with foo.bar.A.getValue1(java.util.List) The return type is incompatible with foo.bar.A.getValue2(T2[]) The return type is incompatible with foo.bar.A.getValue3(java.util.List)
Created attachment 215054 [details] Patch for Xtext Patch for org.eclipse.xtext.common.types.util.FeatureOverridesService
Created attachment 215055 [details] Patch for Xtend (Tests) Tests for Xtend
Created 378484 for the problems with the returntypes as mentioned in comment11.
We have to check the compatibility of the type parameters, too. The following is invalid in Java: class A { <T extends CharSequence> void foo() {} } class B extends A { @Override <T extends String> void foo() {} } Please add some tests for function types, too: Java: class A { <T> void foo(T t, Procedure0<? super T> proc) } could be overwritten by class B extends A { <T> void foo(T t, (T)=>void proc) }
Pushed additional tests fix to master
Requested via bug 522520. -M.
