highlight type parameter extends list errors: check once for all refs in refList not to repeat ourselves

java/java-analysis-impl/src/com/intellij/codeInsight/daemon/impl/analysis/GenericsHighlightUtil.java

@@ -333,12 +333,6 @@ public class GenericsHighlightUtil {
         JavaPsiFacade.getInstance(aClass.getProject()).getElementFactory().createType(extendFrom, resolveResult.getSubstitutor());
       QuickFixAction.registerQuickFixAction(errorResult, QUICK_FIX_FACTORY.createExtendsListFix(aClass, type, false), null);
     }
-    if (errorResult == null && languageLevel.isAtLeast(LanguageLevel.JDK_1_7) &&
-        referenceElements.length > 1) {
-      //todo suppress erased methods which come from the same class
-      final Collection<HighlightInfo> result = checkOverrideEquivalentMethods(aClass);
-      return result != null && !result.isEmpty() ? result.iterator().next() : null;
-    }
     return errorResult;
   }
 
@@ -1412,5 +1406,19 @@ public class GenericsHighlightUtil {
     }
     return null;
   }
+
+  public static HighlightInfo checkTypeParameterOverrideEquivalentMethods(PsiClass aClass, LanguageLevel level) {
+    if (aClass instanceof PsiTypeParameter && level.isAtLeast(LanguageLevel.JDK_1_7)) {
+      final PsiReferenceList extendsList = aClass.getExtendsList();
+      if (extendsList != null && extendsList.getReferenceElements().length > 1) {
+        //todo suppress erased methods which come from the same class
+        final Collection<HighlightInfo> result = GenericsHighlightUtil.checkOverrideEquivalentMethods(aClass);
+        if (result != null && !result.isEmpty()) {
+          return result.iterator().next();
+        }
+      }
+    }
+    return null;
+  }
 }
 

java/java-analysis-impl/src/com/intellij/codeInsight/daemon/impl/analysis/HighlightVisitorImpl.java

@@ -396,6 +396,7 @@ public class HighlightVisitorImpl extends JavaElementVisitor implements Highligh
     if (!myHolder.hasErrorResults()) myHolder.add(HighlightUtil.checkImplicitThisReferenceBeforeSuper(aClass, myJavaSdkVersion));
     if (!myHolder.hasErrorResults()) myHolder.add(HighlightClassUtil.checkClassAndPackageConflict(aClass));
     if (!myHolder.hasErrorResults()) myHolder.add(HighlightClassUtil.checkPublicClassInRightFile(aClass));
+    if (!myHolder.hasErrorResults()) myHolder.add(GenericsHighlightUtil.checkTypeParameterOverrideEquivalentMethods(aClass, myLanguageLevel));
   }
 
   @Override

java/java-psi-api/src/com/intellij/psi/util/MethodSignatureUtil.java

@@ -58,8 +58,17 @@ public class MethodSignatureUtil {
       }
     };
 
+  /**
+   * def: (8.4.2 Method Signature) Two method signatures m1 and m2 are override-equivalent iff either m1 is a subsignature of m2 or m2 is a subsignature of m1.
+   *
+   * erasure (erasure) = erasure, so we would check if erasures are equal and then check if the number of type parameters agree: 
+   *      if signature(m1)=signature(m2), then m1.typeParams=m2.typeParams
+   *      if (erasure(signature(m1))=signature(m2), then m2.typeParams.length=0 and vise versa
+   */
   public static boolean areOverrideEquivalent(PsiMethod method1, PsiMethod method2) {
-    return method1.getTypeParameters().length == method2.getTypeParameters().length &&
+    final int typeParamsLength1 = method1.getTypeParameters().length;
+    final int typeParamsLength2 = method2.getTypeParameters().length;
+    return (typeParamsLength1 == typeParamsLength2 || typeParamsLength1 == 0 || typeParamsLength2 == 0) &&
            areErasedParametersEqual(method1.getSignature(PsiSubstitutor.EMPTY), method2.getSignature(PsiSubstitutor.EMPTY));
   }
   

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/advHighlighting7/ambiguousMultipleTypeParamExtends1/pck/AmbiguousMethodCall.java

@@ -10,6 +10,6 @@ interface IB{
 }
 class C {
     <<error descr="'foo(A<T>)' in 'pck.IB' clashes with 'foo(A<?>)' in 'pck.IA'; both methods have same erasure, yet neither overrides the other"></error>T extends IA & IB> void bar(T x, A<String> y){
-        x.foo<error descr="Ambiguous method call: both 'IA.foo(A<?>)' and 'IB.foo(A<String>)' match">(y)</error>;
+        x.foo(y);
     }
 }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/genericsHighlighting8/IDEA67672.java

@@ -3,5 +3,5 @@ import java.util.List;
 
 interface A
 {
-    <<error descr="'add(E)' in 'java.util.List' clashes with 'add(E)' in 'java.util.Collection'; both methods have same erasure, yet neither overrides the other"></error><error descr="'add(E)' in 'java.util.List' clashes with 'add(E)' in 'java.util.Collection'; both methods have same erasure, yet neither overrides the other"></error>T extends List<?> & Collection<? extends Cloneable>> void foo(T x);
+    <<error descr="'java.util.Collection' cannot be inherited with different type arguments: 'capture<?>' and 'capture<? extends java.lang.Cloneable>'"></error>T extends List<?> & Collection<? extends Cloneable>> void foo(T x);
 }