default methods: check unrelated defaults (IDEA-91685;IDEA-98792)

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/advHighlighting7/InheritUnrelatedDefaults.java

@@ -0,0 +1,3 @@
+interface B { default void foo() {} }
+interface C { default void foo() {} }
+class <error descr="D inherits unrelated defaults for foo() from types B and C">D</error> implements B, C {}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/advHighlighting7/NotInheritFromUnrelatedDefault.java

@@ -0,0 +1,15 @@
+interface FirstParent {
+
+    default int doSomething() {
+        return 1;
+    }
+}
+
+interface SecondParent {
+
+    int doSomething();
+}
+
+class <error descr="Class 'SecondParent' must either be declared abstract or implement abstract method 'doSomething()' in 'SecondParent'">FirstSon</error> implements FirstParent, SecondParent {}
+
+<error descr="Class 'SecondSon' must either be declared abstract or implement abstract method 'doSomething()' in 'SecondParent'">class SecondSon implements SecondParent, FirstParent</error> {}