Check componentN functions for overload conflicts

compiler/frontend/src/org/jetbrains/jet/lang/resolve/OverloadResolver.java

@@ -210,7 +210,9 @@ public class OverloadResolver {
                 if (!overloadable.isSuccess()) {
                     JetDeclaration jetDeclaration = (JetDeclaration) BindingContextUtils
                             .descriptorToDeclaration(trace.getBindingContext(), member);
-                    redeclarations.add(Pair.create(jetDeclaration, member));
+                    if (jetDeclaration != null) {
+                        redeclarations.add(Pair.create(jetDeclaration, member));
+                    }
                 }
             }
         }

compiler/testData/diagnostics/tests/dataClasses/conflictingOverloads.kt

@@ -0,0 +1,4 @@
+data class A(val x: Int, val y: String) {
+    <!CONFLICTING_OVERLOADS!>fun component1()<!> = 1
+    <!CONFLICTING_OVERLOADS!>fun component2()<!> = 2
+}

compiler/tests/org/jetbrains/jet/checkers/JetDiagnosticsTestGenerated.java

@@ -977,6 +977,11 @@ public class JetDiagnosticsTestGenerated extends AbstractDiagnosticsTestWithEage
                 doTest("compiler/testData/diagnostics/tests/dataClasses/componentNamedComponent1.kt");
             }
             
+            @TestMetadata("conflictingOverloads.kt")
+            public void testConflictingOverloads() throws Exception {
+                doTest("compiler/testData/diagnostics/tests/dataClasses/conflictingOverloads.kt");
+            }
+            
             @TestMetadata("dataClassOverrideConflict.kt")
             public void testDataClassOverrideConflict() throws Exception {
                 doTest("compiler/testData/diagnostics/tests/dataClasses/dataClassOverrideConflict.kt");