From cbebb065745c5cef6e9d6cf98d4207796288b0f7 Mon Sep 17 00:00:00 2001
From: Denis Zharkov <denis.zharkov@jetbrains.com>
Date: Wed, 30 Nov 2016 17:10:47 +0300
Subject: [PATCH] Do not return star-projections during approximation

See comment in test for clarification

 #KT-14453 Fixed
---
 .../capturedTypes/starProjectionRegression.kt   | 17 +++++++++++++++++
 .../capturedTypes/starProjectionRegression.txt  | 16 ++++++++++++++++
 .../checkers/DiagnosticsTestGenerated.java      |  6 ++++++
 .../kotlin/types/CapturedTypeApproximation.kt   |  6 +++++-
 4 files changed, 44 insertions(+), 1 deletion(-)
 create mode 100644 compiler/testData/diagnostics/tests/inference/capturedTypes/starProjectionRegression.kt
 create mode 100644 compiler/testData/diagnostics/tests/inference/capturedTypes/starProjectionRegression.txt

diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/starProjectionRegression.kt b/compiler/testData/diagnostics/tests/inference/capturedTypes/starProjectionRegression.kt
new file mode 100644
index 00000000000..bfee91bf948
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/starProjectionRegression.kt
@@ -0,0 +1,17 @@
+// See KT-14453
+val <T : Any> KClass1<T>.primaryConstructor: KFunction1<T>? get() = null!!
+
+interface KClass1<F : Any>
+interface KFunction1<out R>
+fun f(type: KClass1<*>): KFunction1<Any>? =
+        // What happens here:
+        // 1. Create captured type for type argument T (it's built upon star-projection from `KClass<*>` that's argument is <: Any)
+        // 2. Approximate resulting descriptor, now it 'KClass1<*>.primaryConstructor: KFunction1<*>'
+        //    Note that star-projection in 'KFunction1<*>' is obtained from KClass and its `projectionType` is Any (not-nullable).
+        //    Of course that situation is already strange
+        // 3. When checking subtyping after call completion we get that 'KFunction1<*>' is not a subtype of 'KFunction1<Any>' in new type checker.
+        //    The answer is correct, but this old type checker used `projectionType` for this and it was resulting in KFunction1<*> <: KFunction1<Any>
+        //
+        // So to fix the issue we use 'out starProjectionType' instead of star-projection itself in approximation
+        // Note that in new inference there should be no approximation for IN-position types (they must remain captured)
+        type.primaryConstructor
diff --git a/compiler/testData/diagnostics/tests/inference/capturedTypes/starProjectionRegression.txt b/compiler/testData/diagnostics/tests/inference/capturedTypes/starProjectionRegression.txt
new file mode 100644
index 00000000000..690efd1d759
--- /dev/null
+++ b/compiler/testData/diagnostics/tests/inference/capturedTypes/starProjectionRegression.txt
@@ -0,0 +1,16 @@
+package
+
+public val </*0*/ T : kotlin.Any> KClass1<T>.primaryConstructor: KFunction1<T>?
+public fun f(/*0*/ type: KClass1<*>): KFunction1<kotlin.Any>?
+
+public interface KClass1</*0*/ F : kotlin.Any> {
+    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 KFunction1</*0*/ out R> {
+    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
+}
diff --git a/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java b/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java
index e9833b71c64..10c682fa4ef 100644
--- a/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java
+++ b/compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java
@@ -9740,6 +9740,12 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                     String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/inference/capturedTypes/overApproximationForOutCaptured.kt");
                     doTest(fileName);
                 }
+
+                @TestMetadata("starProjectionRegression.kt")
+                public void testStarProjectionRegression() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/diagnostics/tests/inference/capturedTypes/starProjectionRegression.kt");
+                    doTest(fileName);
+                }
             }
 
             @TestMetadata("compiler/testData/diagnostics/tests/inference/commonSystem")
diff --git a/core/descriptors/src/org/jetbrains/kotlin/types/CapturedTypeApproximation.kt b/core/descriptors/src/org/jetbrains/kotlin/types/CapturedTypeApproximation.kt
index e989b9a9eed..81ad0a3eb57 100644
--- a/core/descriptors/src/org/jetbrains/kotlin/types/CapturedTypeApproximation.kt
+++ b/core/descriptors/src/org/jetbrains/kotlin/types/CapturedTypeApproximation.kt
@@ -86,7 +86,11 @@ fun approximateCapturedTypesIfNecessary(typeProjection: TypeProjection?, approxi
 private fun substituteCapturedTypesWithProjections(typeProjection: TypeProjection): TypeProjection? {
     val typeSubstitutor = TypeSubstitutor.create(object : TypeConstructorSubstitution() {
         override fun get(key: TypeConstructor): TypeProjection? {
-            return (key as? CapturedTypeConstructor)?.typeProjection
+            val capturedTypeConstructor = key as? CapturedTypeConstructor ?: return null
+            if (capturedTypeConstructor.typeProjection.isStarProjection) {
+                return TypeProjectionImpl(Variance.OUT_VARIANCE, capturedTypeConstructor.typeProjection.type)
+            }
+            return capturedTypeConstructor.typeProjection
         }
     })
     return typeSubstitutor.substituteWithoutApproximation(typeProjection)