Allow top-level type aliases in scripts

compiler/frontend/src/org/jetbrains/kotlin/resolve/DescriptorResolver.java

@@ -698,7 +698,8 @@ public class DescriptorResolver {
             @NotNull KtTypeAlias typeAlias,
             @NotNull BindingTrace trace
     ) {
-        if (!(containingDeclaration instanceof PackageFragmentDescriptor)) {
+        if (!(containingDeclaration instanceof PackageFragmentDescriptor) &&
+            !(containingDeclaration instanceof ScriptDescriptor)) {
             trace.report(TOPLEVEL_TYPEALIASES_ONLY.on(typeAlias));
         }
 

compiler/testData/codegen/script/topLevelTypealias.kts

@@ -0,0 +1,9 @@
+class SimpleClass(val s: String) {
+    fun foo() = s
+}
+
+typealias Test = SimpleClass
+
+val rv = Test("OK").foo()
+
+// expected: rv: OK

compiler/testData/diagnostics/tests/script/typealiasInScript.kts

@@ -0,0 +1,9 @@
+typealias TopLevelInScript = String
+
+class C {
+    <!TOPLEVEL_TYPEALIASES_ONLY!>typealias NestedInClass = String<!>
+}
+
+fun foo() {
+    <!TOPLEVEL_TYPEALIASES_ONLY!>typealias Local = String<!>
+}

compiler/testData/diagnostics/tests/script/typealiasInScript.txt

@@ -0,0 +1,19 @@
+package
+
+public final class TypealiasInScript : kotlin.script.templates.standard.ScriptTemplateWithArgs {
+    public constructor TypealiasInScript(/*0*/ args: kotlin.Array<kotlin.String>)
+    public final override /*1*/ /*fake_override*/ val args: kotlin.Array<kotlin.String>
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public final fun foo(): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+
+    public final class C {
+        public constructor C()
+        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
+        public typealias NestedInClass = kotlin.String
+    }
+    public typealias TopLevelInScript = kotlin.String
+}

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

@@ -23605,6 +23605,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/script/topLevelVariable.kts");
             doTest(fileName);
         }
+
+        @TestMetadata("typealiasInScript.kts")
+        public void testTypealiasInScript() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/script/typealiasInScript.kts");
+            doTest(fileName);
+        }
     }
 
     @TestMetadata("compiler/testData/codegen/box/diagnostics")

compiler/tests/org/jetbrains/kotlin/codegen/ScriptCodegenTestGenerated.java

@@ -173,4 +173,10 @@ public class ScriptCodegenTestGenerated extends AbstractScriptCodegenTest {
         String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/script/topLevelProperty.kts");
         doTest(fileName);
     }
+
+    @TestMetadata("topLevelTypealias.kts")
+    public void testTopLevelTypealias() throws Exception {
+        String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/script/topLevelTypealias.kts");
+        doTest(fileName);
+    }
 }