search for method implementations with correct substitutor

java/java-impl/src/com/intellij/codeInsight/intention/impl/ImplementAbstractMethodHandler.java

@@ -40,7 +40,9 @@ import com.intellij.openapi.ui.popup.PopupChooserBuilder;
 import com.intellij.openapi.util.Computable;
 import com.intellij.psi.*;
 import com.intellij.psi.search.searches.ClassInheritorsSearch;
+import com.intellij.psi.util.MethodSignatureUtil;
 import com.intellij.psi.util.PsiUtilCore;
+import com.intellij.psi.util.TypeConversionUtil;
 import com.intellij.ui.components.JBList;
 import com.intellij.util.IncorrectOperationException;
 
@@ -180,7 +182,9 @@ public class ImplementAbstractMethodHandler {
     ArrayList<PsiClass> list = new ArrayList<PsiClass>();
     for (PsiClass inheritor : ClassInheritorsSearch.search(psiClass, true)) {
       if (!inheritor.isInterface()) {
-        PsiMethod method = inheritor.findMethodBySignature(myMethod, true);
+        final PsiSubstitutor classSubstitutor = TypeConversionUtil.getClassSubstitutor(psiClass, inheritor, PsiSubstitutor.EMPTY);
+        LOG.assertTrue(classSubstitutor != null);
+        PsiMethod method = MethodSignatureUtil.findMethodBySignature(inheritor, myMethod.getSignature(classSubstitutor), true);
         if (method == null || !method.getContainingClass().equals(psiClass)) continue;
         list.add(inheritor);
       }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/implementMethods/afterMultipleImplementationsAlreadyExist.java

@@ -0,0 +1,20 @@
+// "Implement method 'foo'" "true"
+
+abstract class A<T> {
+    abstract String foo(T t);
+}
+
+class B extends A<String> {
+
+    @Override
+    String foo(String s1) {
+        return null;
+    }
+}
+
+class ABC extends A<Integer> {
+    @Override
+    String foo(Integer integer) {
+        return null;
+    }
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/quickFix/implementMethods/beforeMultipleImplementationsAlreadyExist.java

@@ -0,0 +1,15 @@
+// "Implement method 'foo'" "true"
+
+abstract class A<T> {
+    abstract String f<caret>oo(T t);
+}
+
+class B extends A<String> {
+
+    @Override
+    String foo(String s1) {
+        return null;
+    }
+}
+
+class ABC extends A<Integer> {}