FIR: Fix incorrect handling bare types when subject is type alias

^KT-39043 Fixed

compiler/fir/analysis-tests/testData/resolve/types/bareWithSubjectTypeAlias.kt

@@ -0,0 +1,14 @@
+sealed class A<out T> {
+    class B<out T1>(val x: T1) : A<T1>()
+    class C<out T2>(val y: T2) : A<T2>()
+}
+
+typealias TA = A<CharSequence>
+
+fun bar(): TA = TODO()
+
+fun foo() {
+    when (val a = bar()) {
+        is A.B -> a.x.length
+    }
+}

compiler/fir/analysis-tests/testData/resolve/types/bareWithSubjectTypeAlias.txt

@@ -0,0 +1,39 @@
+FILE: bareWithSubjectTypeAlias.kt
+    public sealed class A<out T> : R|kotlin/Any| {
+        private constructor<out T>(): R|A<T>| {
+            super<R|kotlin/Any|>()
+        }
+
+        public final class B<out T1> : R|A<T1>| {
+            public constructor<out T1>(x: R|T1|): R|A.B<T1>| {
+                super<R|A<T1>|>()
+            }
+
+            public final val x: R|T1| = R|<local>/x|
+                public get(): R|T1|
+
+        }
+
+        public final class C<out T2> : R|A<T2>| {
+            public constructor<out T2>(y: R|T2|): R|A.C<T2>| {
+                super<R|A<T2>|>()
+            }
+
+            public final val y: R|T2| = R|<local>/y|
+                public get(): R|T2|
+
+        }
+
+    }
+    public final typealias TA = R|A<kotlin/CharSequence>|
+    public final fun bar(): R|TA| {
+        ^bar R|kotlin/TODO|()
+    }
+    public final fun foo(): R|kotlin/Unit| {
+        when (lval a: R|TA| = R|/bar|()) {
+            ($subj$ is R|A.B<kotlin/CharSequence>|) ->  {
+                R|<local>/a|.R|FakeOverride</A.B.x: R|kotlin/CharSequence|>|.R|kotlin/CharSequence.length|
+            }
+        }
+
+    }

compiler/fir/analysis-tests/tests/org/jetbrains/kotlin/fir/FirDiagnosticsTestGenerated.java

@@ -2241,6 +2241,24 @@ public class FirDiagnosticsTestGenerated extends AbstractFirDiagnosticsTest {
         }
     }
 
+    @TestMetadata("compiler/fir/analysis-tests/testData/resolve/types")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class Types extends AbstractFirDiagnosticsTest {
+        private void runTest(String testDataFilePath) throws Exception {
+            KotlinTestUtils.runTest(this::doTest, this, testDataFilePath);
+        }
+
+        public void testAllFilesPresentInTypes() throws Exception {
+            KotlinTestUtils.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/fir/analysis-tests/testData/resolve/types"), Pattern.compile("^([^.]+)\\.kt$"), null, true);
+        }
+
+        @TestMetadata("bareWithSubjectTypeAlias.kt")
+        public void testBareWithSubjectTypeAlias() throws Exception {
+            runTest("compiler/fir/analysis-tests/testData/resolve/types/bareWithSubjectTypeAlias.kt");
+        }
+    }
+
     @TestMetadata("compiler/fir/analysis-tests/testData/resolve/visibility")
     @TestDataPath("$PROJECT_ROOT")
     @RunWith(JUnit3RunnerWithInners.class)

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

@@ -2241,6 +2241,24 @@ public class FirDiagnosticsWithLightTreeTestGenerated extends AbstractFirDiagnos
         }
     }
 
+    @TestMetadata("compiler/fir/analysis-tests/testData/resolve/types")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class Types extends AbstractFirDiagnosticsWithLightTreeTest {
+        private void runTest(String testDataFilePath) throws Exception {
+            KotlinTestUtils.runTest(this::doTest, this, testDataFilePath);
+        }
+
+        public void testAllFilesPresentInTypes() throws Exception {
+            KotlinTestUtils.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("compiler/fir/analysis-tests/testData/resolve/types"), Pattern.compile("^([^.]+)\\.kt$"), null, true);
+        }
+
+        @TestMetadata("bareWithSubjectTypeAlias.kt")
+        public void testBareWithSubjectTypeAlias() throws Exception {
+            runTest("compiler/fir/analysis-tests/testData/resolve/types/bareWithSubjectTypeAlias.kt");
+        }
+    }
+
     @TestMetadata("compiler/fir/analysis-tests/testData/resolve/visibility")
     @TestDataPath("$PROJECT_ROOT")
     @RunWith(JUnit3RunnerWithInners.class)

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/ResolveUtils.kt

@@ -8,13 +8,15 @@ package org.jetbrains.kotlin.fir.resolve
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns
 import org.jetbrains.kotlin.builtins.functions.FunctionClassDescriptor
 import org.jetbrains.kotlin.descriptors.ClassKind
-import org.jetbrains.kotlin.fir.*
+import org.jetbrains.kotlin.fir.FirSession
+import org.jetbrains.kotlin.fir.FirSourceElement
 import org.jetbrains.kotlin.fir.declarations.*
 import org.jetbrains.kotlin.fir.diagnostics.ConeStubDiagnostic
 import org.jetbrains.kotlin.fir.expressions.*
 import org.jetbrains.kotlin.fir.expressions.builder.FirResolvedReifiedParameterReferenceBuilder
 import org.jetbrains.kotlin.fir.expressions.builder.buildExpressionWithSmartcast
 import org.jetbrains.kotlin.fir.expressions.builder.buildResolvedQualifier
+import org.jetbrains.kotlin.fir.inferenceContext
 import org.jetbrains.kotlin.fir.references.FirErrorNamedReference
 import org.jetbrains.kotlin.fir.references.FirResolvedNamedReference
 import org.jetbrains.kotlin.fir.references.FirSuperReference
@@ -28,6 +30,7 @@ import org.jetbrains.kotlin.fir.resolve.providers.bindSymbolToLookupTag
 import org.jetbrains.kotlin.fir.resolve.providers.getSymbolByTypeRef
 import org.jetbrains.kotlin.fir.resolve.substitution.AbstractConeSubstitutor
 import org.jetbrains.kotlin.fir.resolve.transformers.body.resolve.resultType
+import org.jetbrains.kotlin.fir.resolvedTypeFromPrototype
 import org.jetbrains.kotlin.fir.scopes.impl.FirDeclaredMemberScopeProvider
 import org.jetbrains.kotlin.fir.scopes.impl.withReplacedConeType
 import org.jetbrains.kotlin.fir.symbols.*
@@ -87,6 +90,15 @@ fun ConeClassLikeType.fullyExpandedType(
     return fullyExpandedTypeNoCache(useSiteSession, expandedConeType)
 }
 
+fun ConeKotlinType.fullyExpandedType(
+    useSiteSession: FirSession
+): ConeKotlinType = when (this) {
+    is ConeFlexibleType ->
+        ConeFlexibleType(lowerBound.fullyExpandedType(useSiteSession), upperBound.fullyExpandedType(useSiteSession))
+    is ConeClassLikeType -> fullyExpandedType(useSiteSession)
+    else -> this
+}
+
 private fun ConeClassLikeType.fullyExpandedTypeNoCache(
     useSiteSession: FirSession,
     expandedConeType: (FirTypeAlias) -> ConeClassLikeType?,

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

@@ -34,7 +34,6 @@ import org.jetbrains.kotlin.fir.symbols.impl.FirClassSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirVariableSymbol
 import org.jetbrains.kotlin.fir.types.*
 import org.jetbrains.kotlin.fir.types.builder.*
-import org.jetbrains.kotlin.fir.types.impl.FirQualifierPartImpl
 import org.jetbrains.kotlin.fir.visitors.*
 import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.Name
@@ -379,7 +378,9 @@ open class FirExpressionsResolveTransformer(transformer: FirBodyResolveTransform
     }
 
     private fun FirTypeRef.withTypeArgumentsForBareType(argument: FirExpression): FirTypeRef {
-        val baseTypeArguments = argument.typeRef.coneTypeSafe<ConeKotlinType>()?.typeArguments
+        // TODO: Everything should also work for case of checked-type itself is a type alias
+        val baseTypeArguments =
+            argument.typeRef.coneTypeSafe<ConeKotlinType>()?.fullyExpandedType(session)?.typeArguments
         val type = coneTypeSafe<ConeKotlinType>()
         return if (type?.typeArguments?.isEmpty() != true ||
             type is ConeTypeParameterType ||