Render stub types properly

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsTestGenerated.java

@@ -12638,6 +12638,12 @@ public class FirOldFrontendDiagnosticsTestGenerated extends AbstractFirDiagnosti
                     KtTestUtil.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/testData/diagnostics/tests/inference/builderInference"), Pattern.compile("^(.+)\\.kt$"), Pattern.compile("^(.+)\\.fir\\.kts?$"), true);
                 }
 
+                @Test
+                @TestMetadata("renderingStubTypes.kt")
+                public void testRenderingStubTypes() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/inference/builderInference/renderingStubTypes.kt");
+                }
+
                 @Test
                 @TestMetadata("simpleLambdaInCallWithAnotherLambdaWithBuilderInference.kt")
                 public void testSimpleLambdaInCallWithAnotherLambdaWithBuilderInference() throws Exception {

compiler/fir/analysis-tests/tests-gen/org/jetbrains/kotlin/test/runners/FirOldFrontendDiagnosticsWithLightTreeTestGenerated.java

@@ -12638,6 +12638,12 @@ public class FirOldFrontendDiagnosticsWithLightTreeTestGenerated extends Abstrac
                     KtTestUtil.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/testData/diagnostics/tests/inference/builderInference"), Pattern.compile("^(.+)\\.kt$"), Pattern.compile("^(.+)\\.fir\\.kts?$"), true);
                 }
 
+                @Test
+                @TestMetadata("renderingStubTypes.kt")
+                public void testRenderingStubTypes() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/inference/builderInference/renderingStubTypes.kt");
+                }
+
                 @Test
                 @TestMetadata("simpleLambdaInCallWithAnotherLambdaWithBuilderInference.kt")
                 public void testSimpleLambdaInCallWithAnotherLambdaWithBuilderInference() throws Exception {

compiler/testData/diagnostics/tests/inference/builderInference/renderingStubTypes.fir.kt

@@ -0,0 +1,25 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -DEPRECATION -EXPERIMENTAL_IS_NOT_ENABLED -UNUSED_VARIABLE
+// WITH_RUNTIME
+
+import kotlin.experimental.ExperimentalTypeInference
+
+@UseExperimental(ExperimentalTypeInference::class)
+fun <R> build(
+    @BuilderInference block: TestInterface<R>.() -> Unit
+): R = TODO()
+
+class Inv<K>
+
+interface TestInterface<R> {
+    fun emit(r: R)
+    fun get(): R
+    fun getInv(): Inv<R>
+}
+
+fun test() {
+    val ret = build {
+        emit(1)
+        get()
+        getInv()
+    }
+}

compiler/testData/diagnostics/tests/inference/builderInference/renderingStubTypes.kt

@@ -0,0 +1,28 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER -DEPRECATION -EXPERIMENTAL_IS_NOT_ENABLED -UNUSED_VARIABLE
+// WITH_RUNTIME
+
+import kotlin.experimental.ExperimentalTypeInference
+
+@UseExperimental(ExperimentalTypeInference::class)
+fun <R> build(
+    @BuilderInference block: TestInterface<R>.() -> Unit
+): R = TODO()
+
+class Inv<K>
+
+interface TestInterface<R> {
+    fun emit(r: R)
+    fun get(): R
+    fun getInv(): Inv<R>
+}
+
+fun <U> id(x: U) = x
+
+fun test() {
+    val ret = build {
+        emit("1")
+        <!DEBUG_INFO_EXPRESSION_TYPE("TypeVariable(R)")!>get()<!>
+        <!DEBUG_INFO_EXPRESSION_TYPE("Inv<TypeVariable(R)>")!>getInv()<!>
+        ""
+    }
+}

compiler/testData/diagnostics/tests/inference/builderInference/renderingStubTypes.txt

@@ -0,0 +1,21 @@
+package
+
+@kotlin.UseExperimental(markerClass = {kotlin.experimental.ExperimentalTypeInference::class}) public fun </*0*/ R> build(/*0*/ @kotlin.BuilderInference block: TestInterface<R>.() -> kotlin.Unit): R
+public fun </*0*/ U> id(/*0*/ x: U): U
+public fun test(): kotlin.Unit
+
+public final class Inv</*0*/ K> {
+    public constructor Inv</*0*/ K>()
+    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 interface TestInterface</*0*/ R> {
+    public abstract fun emit(/*0*/ r: R): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public abstract fun get(): R
+    public abstract fun getInv(): Inv<R>
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/DiagnosticTestGenerated.java

@@ -12644,6 +12644,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
                     KtTestUtil.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/testData/diagnostics/tests/inference/builderInference"), Pattern.compile("^(.*)\\.kts?$"), Pattern.compile("^(.+)\\.fir\\.kts?$"), true);
                 }
 
+                @Test
+                @TestMetadata("renderingStubTypes.kt")
+                public void testRenderingStubTypes() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/inference/builderInference/renderingStubTypes.kt");
+                }
+
                 @Test
                 @TestMetadata("simpleLambdaInCallWithAnotherLambdaWithBuilderInference.kt")
                 public void testSimpleLambdaInCallWithAnotherLambdaWithBuilderInference() throws Exception {

core/descriptors/src/org/jetbrains/kotlin/renderer/DescriptorRendererImpl.kt

@@ -236,19 +236,21 @@ internal class DescriptorRendererImpl(
     private fun StringBuilder.renderDefaultType(type: KotlinType) {
         this.renderAnnotations(type)
 
-        if (type.isError) {
+        when {
-            if (type is UnresolvedType && presentableUnresolvedTypes) {
+            type.isError -> {
-                append(type.presentableName)
+                if (type is UnresolvedType && presentableUnresolvedTypes) {
-            } else {
-                if (type is ErrorType && !informativeErrorType) {
                     append(type.presentableName)
                 } else {
-                    append(type.constructor.toString()) // Debug name of an error type is more informative
+                    if (type is ErrorType && !informativeErrorType) {
+                        append(type.presentableName)
+                    } else {
+                        append(type.constructor.toString()) // Debug name of an error type is more informative
+                    }
                 }
+                append(renderTypeArguments(type.arguments))
             }
-            append(renderTypeArguments(type.arguments))
+            type is StubType -> append(type.originalTypeVariable.toString())
-        } else {
+            else -> renderTypeConstructorAndArguments(type)
-            renderTypeConstructorAndArguments(type)
         }
 
         if (type.isMarkedNullable) {

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

@@ -36,7 +36,7 @@ class StubTypeForProvideDelegateReceiver(
 }
 
 abstract class AbstractStubType(
-    protected val originalTypeVariable: TypeConstructor,
+    val originalTypeVariable: TypeConstructor,
     override val isMarkedNullable: Boolean,
     override val constructor: TypeConstructor,
     override val memberScope: MemberScope