KT-11750 Do not report REDECLARATION on descriptors which are not available in sources.

compiler/frontend/src/org/jetbrains/kotlin/resolve/DeclarationResolver.kt

@@ -78,9 +78,13 @@ class DeclarationResolver(
                             continue
                         }
 
-                        redeclarations.add(Pair(DescriptorToSourceUtils.getSourceFromDescriptor(descriptor)!!, descriptor.getName()))
+                        DescriptorToSourceUtils.getSourceFromDescriptor(descriptor)?.let {
+                            redeclarations.add(Pair(it, descriptor.getName()))
+                        }
                         if (descriptor2 is PropertyDescriptor) {
-                            redeclarations.add(Pair(DescriptorToSourceUtils.descriptorToDeclaration(descriptor2)!!, descriptor2.getName()))
+                            DescriptorToSourceUtils.descriptorToDeclaration(descriptor2)?.let {
+                                redeclarations.add(Pair(it, descriptor2.getName()))
+                            }
                         }
                     }
                 }

compiler/testData/diagnostics/tests/redeclarations/EnumName.kt

@@ -0,0 +1,3 @@
+enum class A {
+    <!REDECLARATION!>name<!>
+}

compiler/testData/diagnostics/tests/redeclarations/EnumName.txt

@@ -0,0 +1,18 @@
+package
+
+public final enum class A : kotlin.Enum<A> {
+    enum entry name
+
+    private constructor A()
+    public final override /*1*/ /*fake_override*/ val name: kotlin.String
+    public final override /*1*/ /*fake_override*/ val ordinal: kotlin.Int
+    protected final override /*1*/ /*fake_override*/ fun clone(): kotlin.Any
+    public final override /*1*/ /*fake_override*/ fun compareTo(/*0*/ other: A): kotlin.Int
+    public final override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public final override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+
+    // Static members
+    public final /*synthesized*/ fun valueOf(/*0*/ value: kotlin.String): A
+    public final /*synthesized*/ fun values(): kotlin.Array<A>
+}

compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -13377,6 +13377,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("EnumName.kt")
+            public void testEnumName() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/redeclarations/EnumName.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("FunVsCtorInDifferentFiles.kt")
             public void testFunVsCtorInDifferentFiles() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/redeclarations/FunVsCtorInDifferentFiles.kt");