[FIR] Fix inferring arguments of bare types in different situations

- argument type is flexible
- supertype has flexible type argument
- type of expression is more specific than bare type

compiler/fir/analysis-tests/legacy-fir-tests/tests-gen/org/jetbrains/kotlin/fir/LazyBodyIsNotTouchedTilContractsPhaseTestGenerated.java

@@ -39,6 +39,16 @@ public class LazyBodyIsNotTouchedTilContractsPhaseTestGenerated extends Abstract
         runTest("compiler/fir/analysis-tests/testData/resolve/bareTypes.kt");
     }
 
+    @TestMetadata("bareTypes2.kt")
+    public void testBareTypes2() throws Exception {
+        runTest("compiler/fir/analysis-tests/testData/resolve/bareTypes2.kt");
+    }
+
+    @TestMetadata("bareTypesWithFlexibleArguments.kt")
+    public void testBareTypesWithFlexibleArguments() throws Exception {
+        runTest("compiler/fir/analysis-tests/testData/resolve/bareTypesWithFlexibleArguments.kt");
+    }
+
     @TestMetadata("cast.kt")
     public void testCast() throws Exception {
         runTest("compiler/fir/analysis-tests/testData/resolve/cast.kt");

compiler/fir/analysis-tests/testData/resolve/bareTypes2.fir.txt

@@ -0,0 +1,32 @@
+FILE: bareTypes2.kt
+    public abstract interface A<D : R|A<D>|> : R|kotlin/Any| {
+        public abstract fun foo(): R|kotlin/Any|
+
+        public abstract val cond: R|kotlin/Boolean|
+            public get(): R|kotlin/Boolean|
+
+        public abstract val field: R|kotlin/Any|
+            public get(): R|kotlin/Any|
+
+    }
+    public abstract interface B<F : R|B<F>|> : R|A<F>| {
+        public abstract override fun foo(): R|kotlin/CharSequence|
+
+    }
+    public abstract interface C : R|B<C>| {
+        public abstract override fun foo(): R|kotlin/String|
+
+    }
+    public final fun test(x: R|A<*>|): R|kotlin/Unit| {
+        when ((R|<local>/x| as? R|C|)?.{ $subj$.R|/A.field| }) {
+            ($subj$ is R|kotlin/String|) ->  {
+                when () {
+                    ==((R|<local>/x| as? R|B<C>|)?.{ $subj$.R|/A.cond| }, Boolean(true)) ->  {
+                        R|<local>/x|.R|/C.foo|()
+                    }
+                }
+
+            }
+        }
+
+    }

compiler/fir/analysis-tests/testData/resolve/bareTypes2.kt

@@ -0,0 +1,25 @@
+interface A<D : A<D>> {
+    fun foo(): Any
+
+    val cond: Boolean
+    val field: Any
+}
+
+interface B<F : B<F>> : A<F> {
+    override fun foo(): CharSequence
+}
+
+interface C : B<C> {
+    override fun foo(): String
+}
+
+fun test(x: A<*>) {
+    when ((x as? C)?.field) {
+        is String -> {
+            if ((x as? B)?.cond == true) {
+                x.foo()
+            }
+        }
+    }
+
+}

compiler/fir/analysis-tests/testData/resolve/bareTypesWithFlexibleArguments.fir.txt

@@ -0,0 +1,11 @@
+FILE: bareTypesWithFlexibleArguments.kt
+    public final fun <T> R|kotlin/collections/Collection<T>?|.concat(collection: R|kotlin/collections/Collection<T>|): R|kotlin/collections/Collection<T>?| {
+        when () {
+            (this@R|/concat| is R|kotlin/collections/LinkedHashSet<T>|) ->  {
+                this@R|/concat|.R|SubstitutionOverride<java/util/LinkedHashSet.addAll: R|kotlin/Boolean|>|(R|<local>/collection|)
+                ^concat this@R|/concat|
+            }
+        }
+
+        ^concat this@R|/concat|
+    }

compiler/fir/analysis-tests/testData/resolve/bareTypesWithFlexibleArguments.kt

@@ -0,0 +1,10 @@
+// WITH_STDLIB
+// FULL_JDK
+
+fun <T> Collection<T>?.concat(collection: Collection<T>): Collection<T>? {
+    if (this is LinkedHashSet) {
+        addAll(collection)
+        return this
+    }
+    return this
+}

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

@@ -38,6 +38,18 @@ public class FirDiagnosticTestGenerated extends AbstractFirDiagnosticTest {
             runTest("compiler/fir/analysis-tests/testData/resolve/bareTypes.kt");
         }
 
+        @Test
+        @TestMetadata("bareTypes2.kt")
+        public void testBareTypes2() throws Exception {
+            runTest("compiler/fir/analysis-tests/testData/resolve/bareTypes2.kt");
+        }
+
+        @Test
+        @TestMetadata("bareTypesWithFlexibleArguments.kt")
+        public void testBareTypesWithFlexibleArguments() throws Exception {
+            runTest("compiler/fir/analysis-tests/testData/resolve/bareTypesWithFlexibleArguments.kt");
+        }
+
         @Test
         @TestMetadata("cast.kt")
         public void testCast() throws Exception {

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

@@ -39,6 +39,18 @@ public class FirDiagnosticsWithLightTreeTestGenerated extends AbstractFirDiagnos
         runTest("compiler/fir/analysis-tests/testData/resolve/bareTypes.kt");
     }
 
+    @Test
+    @TestMetadata("bareTypes2.kt")
+    public void testBareTypes2() throws Exception {
+        runTest("compiler/fir/analysis-tests/testData/resolve/bareTypes2.kt");
+    }
+
+    @Test
+    @TestMetadata("bareTypesWithFlexibleArguments.kt")
+    public void testBareTypesWithFlexibleArguments() throws Exception {
+        runTest("compiler/fir/analysis-tests/testData/resolve/bareTypesWithFlexibleArguments.kt");
+    }
+
     @Test
     @TestMetadata("cast.kt")
     public void testCast() throws Exception {

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/body/resolve/FirExpressionsResolveTransformer.kt

@@ -35,6 +35,7 @@ import org.jetbrains.kotlin.fir.types.builder.*
 import org.jetbrains.kotlin.fir.visitors.*
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.resolve.calls.tower.CandidateApplicability
+import org.jetbrains.kotlin.types.AbstractTypeChecker
 import org.jetbrains.kotlin.types.ConstantValueKind
 import org.jetbrains.kotlin.types.TypeApproximatorConfiguration
 
@@ -473,7 +474,10 @@ open class FirExpressionsResolveTransformer(transformer: FirBodyResolveTransform
         val type = typeRef.coneTypeSafe<ConeClassLikeType>() ?: return null
         val indexMapping = typeParameters.map { parameter ->
             // TODO: if many, check consistency of the result
-            type.typeArguments.indexOfFirst { it is ConeTypeParameterType && it.lookupTag.typeParameterSymbol == parameter.symbol }
+            type.typeArguments.indexOfFirst {
+                val argument = (it as? ConeKotlinType)?.lowerBoundIfFlexible()
+                argument is ConeTypeParameterType && argument.lookupTag.typeParameterSymbol == parameter.symbol
+            }
         }
         if (indexMapping.any { it == -1 }) return null
 
@@ -488,14 +492,23 @@ open class FirExpressionsResolveTransformer(transformer: FirBodyResolveTransform
         val firClass = type.lookupTag.toSymbol(session)?.fir ?: return this
         if (firClass !is FirTypeParameterRefsOwner || firClass.typeParameters.isEmpty()) return this
 
-        val baseType = argument.typeRef.coneTypeSafe<ConeClassLikeType>()?.fullyExpandedType(session) ?: return this
+        val baseType = argument.typeRef.coneTypeSafe<ConeKotlinType>()?.lowerBoundIfFlexible()?.fullyExpandedType(session) ?: return this
+        if (baseType !is ConeClassLikeType) return this
         val baseFirClass = baseType.lookupTag.toSymbol(session)?.fir ?: return this
 
-        val newArguments = type.inheritTypeArguments(baseFirClass, baseType.typeArguments)
+        val newArguments = if (AbstractTypeChecker.isSubtypeOfClass(session.typeCheckerContext, baseType.lookupTag, type.lookupTag)) {
-            ?: return buildErrorTypeRef {
+            // If actual type of declaration is more specific than bare type then we should just find
-                source = this@withTypeArgumentsForBareType.source
+            // corresponding supertype with proper arguments
-                diagnostic = ConeWrongNumberOfTypeArgumentsError(firClass.typeParameters.size, firClass.symbol)
+            with(session.typeContext) {
+                val superType = baseType.fastCorrespondingSupertypes(type.lookupTag)?.firstOrNull() as? ConeKotlinType?
+                superType?.typeArguments
             }
+        } else {
+            type.inheritTypeArguments(baseFirClass, baseType.typeArguments)
+        } ?: return buildErrorTypeRef {
+            source = this@withTypeArgumentsForBareType.source
+            diagnostic = ConeWrongNumberOfTypeArgumentsError(firClass.typeParameters.size, firClass.symbol)
+        }
         return if (newArguments.isEmpty()) this else withReplacedConeType(type.withArguments(newArguments))
     }