From e7bd464a3c186ef9e05fa45813d3a9203951e749 Mon Sep 17 00:00:00 2001
From: Victor Petukhov <victor.petukhov@jetbrains.com>
Date: Fri, 11 Feb 2022 11:41:24 +0300
Subject: [PATCH] [FE 1.0] Check if type variable is bounded in upper by
 incompatible types (resolution stage)

^KT-51221 Fixed
---
 .../calls/components/ResolutionParts.kt       | 19 +++++++++++++++++++
 .../resolve/calls/model/KotlinCallKind.kt     | 10 +++++++---
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/components/ResolutionParts.kt b/compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/components/ResolutionParts.kt
index 0b24afeacad..5a4ecbc47c3 100644
--- a/compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/components/ResolutionParts.kt
+++ b/compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/components/ResolutionParts.kt
@@ -899,4 +899,23 @@ internal object CheckContextReceiversResolutionPart : ResolutionPart() {
         addDiagnostic(NoContextReceiver(candidateContextReceiverParameter))
         return null
     }
+}
+
+internal object CheckIncompatibleTypeVariableUpperBounds : ResolutionPart() {
+    override fun ResolutionCandidate.process(workIndex: Int) = with(getSystem().asConstraintSystemCompleterContext()) {
+        val typeVariables = getSystem().getBuilder().currentStorage().notFixedTypeVariables.values
+
+        for (variableWithConstraints in typeVariables) {
+            val upperTypes = variableWithConstraints.constraints.extractUpperTypes()
+
+            if (upperTypes.isEmptyIntersection()) {
+                val isInferredEmptyIntersectionForbidden =
+                    callComponents.languageVersionSettings.supportsFeature(LanguageFeature.ForbidInferringTypeVariablesIntoEmptyIntersection)
+
+                val errorFactory =
+                    if (isInferredEmptyIntersectionForbidden) ::InferredEmptyIntersectionError else ::InferredEmptyIntersectionWarning
+                addError(errorFactory(upperTypes, variableWithConstraints.typeVariable))
+            }
+        }
+    }
 }
\ No newline at end of file
diff --git a/compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/model/KotlinCallKind.kt b/compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/model/KotlinCallKind.kt
index 51565360b75..14d121fa35a 100644
--- a/compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/model/KotlinCallKind.kt
+++ b/compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/model/KotlinCallKind.kt
@@ -11,6 +11,7 @@ import org.jetbrains.kotlin.resolve.calls.components.CheckCallableReference
 import org.jetbrains.kotlin.resolve.calls.components.CheckContextReceiversResolutionPart
 import org.jetbrains.kotlin.resolve.calls.components.CheckExplicitReceiverKindConsistency
 import org.jetbrains.kotlin.resolve.calls.components.CheckExternalArgument
+import org.jetbrains.kotlin.resolve.calls.components.CheckIncompatibleTypeVariableUpperBounds
 import org.jetbrains.kotlin.resolve.calls.components.CheckInfixResolutionPart
 import org.jetbrains.kotlin.resolve.calls.components.CheckOperatorResolutionPart
 import org.jetbrains.kotlin.resolve.calls.components.CheckReceivers
@@ -38,7 +39,8 @@ enum class KotlinCallKind(vararg resolutionPart: ResolutionPart) {
         CheckExplicitReceiverKindConsistency,
         CheckReceivers,
         PostponedVariablesInitializerResolutionPart,
-        CheckContextReceiversResolutionPart
+        CheckContextReceiversResolutionPart,
+        CheckIncompatibleTypeVariableUpperBounds
     ),
     FUNCTION(
         CheckVisibility,
@@ -58,7 +60,8 @@ enum class KotlinCallKind(vararg resolutionPart: ResolutionPart) {
         CompatibilityOfTypeVariableAsIntersectionTypePart,
         CompatibilityOfPartiallyApplicableSamConversion,
         PostponedVariablesInitializerResolutionPart,
-        CheckContextReceiversResolutionPart
+        CheckContextReceiversResolutionPart,
+        CheckIncompatibleTypeVariableUpperBounds
     ),
     INVOKE(*FUNCTION.resolutionSequence.toTypedArray()),
     CALLABLE_REFERENCE(
@@ -69,7 +72,8 @@ enum class KotlinCallKind(vararg resolutionPart: ResolutionPart) {
         CollectionTypeVariableUsagesInfo,
         CheckReceivers,
         CheckCallableReference,
-        CompatibilityOfTypeVariableAsIntersectionTypePart
+        CompatibilityOfTypeVariableAsIntersectionTypePart,
+        CheckIncompatibleTypeVariableUpperBounds
     ),
     UNSUPPORTED();