Minor. Roll back behaviour for FlexibleType.isError.

compiler/testData/diagnostics/tests/platformTypes/javaEmptyList.kt

@@ -0,0 +1,23 @@
+// !CHECK_TYPE
+
+// FILE: Collections.java
+import java.util.List
+
+public class Collections {
+    public static final <T> List<T> emptyList() {
+}
+
+// FILE: 1.kt
+
+fun bar(): List<String> = null!!
+
+fun test() {
+    val f = if (true) {
+        Collections.emptyList()
+    }
+    else {
+        bar()
+    }
+
+    checkSubtype<List<String>>(f)
+}

compiler/testData/diagnostics/tests/platformTypes/javaEmptyList.txt

@@ -0,0 +1,14 @@
+package
+
+public fun bar(): kotlin.collections.List<kotlin.String>
+public fun test(): kotlin.Unit
+
+public open class Collections {
+    public constructor Collections()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+
+    // Static members
+    public final fun </*0*/ T : kotlin.Any!> emptyList(): kotlin.collections.(Mutable)List<T!>!
+}

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

@@ -12903,6 +12903,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("javaEmptyList.kt")
+            public void testJavaEmptyList() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/platformTypes/javaEmptyList.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("methodTypeParameterDefaultBound.kt")
             public void testMethodTypeParameterDefaultBound() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/platformTypes/methodTypeParameterDefaultBound.kt");

core/descriptors/src/org/jetbrains/kotlin/types/KotlinType.kt

@@ -156,7 +156,7 @@ abstract class FlexibleType(val lowerBound: SimpleType, val upperBound: SimpleTy
     override val arguments: List<TypeProjection> get() = delegate.arguments
     override val isMarkedNullable: Boolean get() = delegate.isMarkedNullable
     override val memberScope: MemberScope get() = delegate.memberScope
-    override val isError: Boolean get() = false
+    override val isError: Boolean get() = delegate.isError // todo should be false?
 
     override fun toString(): String = DescriptorRenderer.DEBUG_TEXT.renderType(this)
 }