Support default methods in interfaces

This removes some false positives on Scala 2.12.0-RC1. Concrete methods
can be added safely (for backwards compatibility) to traits and moved
up in the inheritance hierarchy if they get compiled to default
interface methods.

Author: szeiger

core/src/main/scala/com/typesafe/tools/mima/core/ClassInfo.scala

@@ -155,8 +155,8 @@ abstract class ClassInfo(val owner: PackageInfo) extends HasDeclarationName with
 
   /** The concrete methods of this trait */
   lazy val concreteMethods: List[MemberInfo] = {
-    if(isTrait) methods.iterator.filter(hasStaticImpl(_)).toList
-    else if(isClass) methods.iterator.filter(!_.isDeferred).toList
+    if(isTrait) methods.iterator.filter(m => hasStaticImpl(m) || !m.isDeferred).toList
+    else if(isClass || isInterface) methods.iterator.filter(!_.isDeferred).toList
     else Nil
   }
 

reporter/functional-tests/src/test/abstract-class-extending-new-trait-with-concrete-method-ok/problems-2.12.txt

@@ -1 +0,0 @@
-abstract method foo()Unit in interface B is inherited by class A in new version.

reporter/functional-tests/src/test/trait-abstract-method-becomes-concrete2-ok/problems-2.12.txt

@@ -1 +0,0 @@
-method foo()Int in interface A1 is present only in new version

reporter/functional-tests/src/test/trait-added-method-in-new-version-nok/problems-2.12.txt

@@ -1 +0,0 @@
-method bar()Int in interface A is present only in new version

reporter/functional-tests/src/test/trait-extending-new-trait-with-concrete-method-nok/problems-2.12.txt

@@ -1 +0,0 @@
-abstract method toList(java.lang.Object)scala.collection.immutable.List in interface FoldableToList is inherited by class Foldable in new version.

reporter/functional-tests/src/test/trait-inherits-new-trait-with-concrete-method-nok/problems-2.12.txt

@@ -1,2 +0,0 @@
-abstract method foo()Int in interface AA is inherited by class A in new version.
-abstract method foo()Int in interface AA is inherited by class B in new version.

reporter/functional-tests/src/test/trait-method-overloading-is-ok/problems-2.12.txt

@@ -1 +0,0 @@
-method foo(java.lang.Object)Int in interface A is present only in new version

reporter/functional-tests/src/test/trait-moving-methods-nok/problems-2.12.txt

@@ -1,2 +1 @@
 method foo()Int in interface A does not have a correspondent in new version
-method foo()Int in interface B is present only in new version

reporter/functional-tests/src/test/trait-pushing-up-concrete-methods-is-nok/problems-2.12.txt

@@ -1 +0,0 @@
-method foo()Int in interface A is present only in new version

reporter/src/main/scala/com/typesafe/tools/mima/lib/analyze/Analyzer.scala

@@ -130,7 +130,7 @@ private[analyze] class TraitAnalyzer extends Analyzer {
   override def analyzeNewClassMethods(oldclazz: ClassInfo, newclazz: ClassInfo): List[Problem] = {
     val res = collection.mutable.ListBuffer.empty[Problem]
 
-    for (newmeth <- newclazz.concreteMethods if !oldclazz.hasStaticImpl(newmeth)) {
+    for (newmeth <- newclazz.concreteMethods if newmeth.isDeferred && !oldclazz.hasStaticImpl(newmeth)) {
       if (!oldclazz.lookupMethods(newmeth.bytecodeName).exists(_.sig == newmeth.sig)) {
         // this means that the method is brand new and therefore the implementation
         // has to be injected