Type alias shouldn't expand to a malformed type (e.g., 'Array<Nothing>').

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java

@@ -123,6 +123,7 @@ public interface Errors {
             DiagnosticFactory3.create(ERROR);
     DiagnosticFactory1<KtElement, KotlinType> CONFLICTING_PROJECTION_IN_TYPEALIAS_EXPANSION = DiagnosticFactory1.create(ERROR);
     DiagnosticFactory1<KtTypeReference, KotlinType> TYPEALIAS_SHOULD_EXPAND_TO_CLASS = DiagnosticFactory1.create(ERROR);
+    DiagnosticFactory2<KtTypeReference, KotlinType, String> TYPEALIAS_EXPANDED_TO_MALFORMED_TYPE = DiagnosticFactory2.create(ERROR);
 
     ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java

@@ -427,6 +427,7 @@ public class DefaultErrorMessages {
                 RENDER_TYPE, RENDER_TYPE, NAME);
         MAP.put(CONFLICTING_PROJECTION_IN_TYPEALIAS_EXPANSION, "Conflicting projection in type alias expansion in intermediate type ''{0}''", RENDER_TYPE);
         MAP.put(TYPEALIAS_SHOULD_EXPAND_TO_CLASS, "Type alias expands to {0}, which is not a class, an interface, or an object", RENDER_TYPE);
+        MAP.put(TYPEALIAS_EXPANDED_TO_MALFORMED_TYPE, "Type alias expanded to malformed type {0}: {1}", RENDER_TYPE, STRING);
 
         MAP.put(TOO_MANY_ARGUMENTS, "Too many arguments for {0}", FQ_NAMES_IN_TYPES);
 

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

@@ -36,6 +36,7 @@ import org.jetbrains.kotlin.resolve.DescriptorUtils.classCanHaveOpenMembers
 import org.jetbrains.kotlin.types.*
 import org.jetbrains.kotlin.types.checker.KotlinTypeChecker
 import org.jetbrains.kotlin.types.typeUtil.contains
+import org.jetbrains.kotlin.types.typeUtil.isArrayOfNothing
 import org.jetbrains.kotlin.types.typeUtil.isNothing
 import java.util.*
 
@@ -162,6 +163,10 @@ class DeclarationsChecker(
         if (expandedType.isDynamic() || expandedClassifier is TypeParameterDescriptor) {
             trace.report(TYPEALIAS_SHOULD_EXPAND_TO_CLASS.on(typeReference, expandedType))
         }
+
+        if (TypeUtils.contains(expandedType) { it.isArrayOfNothing()} ) {
+            trace.report(TYPEALIAS_EXPANDED_TO_MALFORMED_TYPE.on(typeReference, expandedType, "Array<Nothing> is illegal"))
+        }
     }
 
     private class TypeAliasDeclarationCheckingReportStrategy(

compiler/testData/diagnostics/tests/typealias/illegalTypeInTypeAliasExpansion.kt

@@ -0,0 +1,6 @@
+typealias A<T> = Array<T>
+typealias AA<T> = A<A<T>>
+
+typealias AN = <!TYPEALIAS_EXPANDED_TO_MALFORMED_TYPE!>A<Nothing><!>
+
+typealias AAN = <!TYPEALIAS_EXPANDED_TO_MALFORMED_TYPE!>AA<Nothing><!>

compiler/testData/diagnostics/tests/typealias/illegalTypeInTypeAliasExpansion.txt

@@ -0,0 +1,6 @@
+package
+
+public typealias A</*0*/ T>  = kotlin.Array<T>
+public typealias AA</*0*/ T>  = A<A<T>>
+public typealias AAN = AA<kotlin.Nothing>
+public typealias AN = A<kotlin.Nothing>

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

@@ -19509,6 +19509,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("illegalTypeInTypeAliasExpansion.kt")
+            public void testIllegalTypeInTypeAliasExpansion() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/typealias/illegalTypeInTypeAliasExpansion.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("import.kt")
             public void testImport() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/typealias/import.kt");