[FIR] Fix resolving of local class reference chain ^KT-47135 Fixed

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/diagnostic/compiler/based/DiagnosisCompilerTestFE10TestdataTestGenerated.java

@@ -24083,6 +24083,12 @@ public class DiagnosisCompilerTestFE10TestdataTestGenerated extends AbstractDiag
                 runTest("compiler/testData/diagnostics/tests/regressions/kt9808.kt");
             }
 
+            @Test
+            @TestMetadata("LocalClassReferenceChain.kt")
+            public void testLocalClassReferenceChain() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/regressions/LocalClassReferenceChain.kt");
+            }
+
             @Test
             @TestMetadata("noThis.kt")
             public void testNoThis() throws Exception {

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

@@ -24083,6 +24083,12 @@ public class FirOldFrontendDiagnosticsTestGenerated extends AbstractFirDiagnosti
                 runTest("compiler/testData/diagnostics/tests/regressions/kt9808.kt");
             }
 
+            @Test
+            @TestMetadata("LocalClassReferenceChain.kt")
+            public void testLocalClassReferenceChain() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/regressions/LocalClassReferenceChain.kt");
+            }
+
             @Test
             @TestMetadata("noThis.kt")
             public void testNoThis() throws Exception {

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

@@ -24083,6 +24083,12 @@ public class FirOldFrontendDiagnosticsWithLightTreeTestGenerated extends Abstrac
                 runTest("compiler/testData/diagnostics/tests/regressions/kt9808.kt");
             }
 
+            @Test
+            @TestMetadata("LocalClassReferenceChain.kt")
+            public void testLocalClassReferenceChain() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/regressions/LocalClassReferenceChain.kt");
+            }
+
             @Test
             @TestMetadata("noThis.kt")
             public void testNoThis() throws Exception {

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/providers/impl/FirTypeResolverImpl.kt

@@ -12,6 +12,7 @@ import org.jetbrains.kotlin.fir.declarations.FirEnumEntry
 import org.jetbrains.kotlin.fir.declarations.FirRegularClass
 import org.jetbrains.kotlin.fir.declarations.impl.FirOuterClassTypeParameterRef
 import org.jetbrains.kotlin.fir.declarations.utils.isEnumClass
+import org.jetbrains.kotlin.fir.declarations.utils.isLocal
 import org.jetbrains.kotlin.fir.diagnostics.ConeSimpleDiagnostic
 import org.jetbrains.kotlin.fir.diagnostics.ConeUnexpectedTypeArgumentsError
 import org.jetbrains.kotlin.fir.diagnostics.DiagnosticKind
@@ -68,19 +69,21 @@ class FirTypeResolverImpl(private val session: FirSession) : FirTypeResolver() {
                 val qualifierResolver = session.qualifierResolver
                 var resolvedSymbol: FirBasedSymbol<*>? = null
                 var substitutor: ConeSubstitutor? = null
-                scope.processClassifiersByNameWithSubstitution(typeRef.qualifier.first().name) { symbol, substitutorFromScope ->
+                val qualifier = typeRef.qualifier
+                scope.processClassifiersByNameWithSubstitution(qualifier.first().name) { symbol, substitutorFromScope ->
                     if (resolvedSymbol != null) return@processClassifiersByNameWithSubstitution
                     resolvedSymbol = when (symbol) {
                         is FirClassLikeSymbol<*> -> {
-                            if (typeRef.qualifier.size == 1) {
+                            if (qualifier.size == 1) {
                                 symbol
                             } else {
-                                qualifierResolver.resolveSymbolWithPrefix(typeRef.qualifier, symbol.classId)
-                                    ?: qualifierResolver.resolveEnumEntrySymbol(typeRef.qualifier, symbol.classId)
+                                resolveLocalClassChain(symbol, qualifier)
+                                    ?: qualifierResolver.resolveSymbolWithPrefix(qualifier, symbol.classId)
+                                    ?: qualifierResolver.resolveEnumEntrySymbol(qualifier, symbol.classId)
                             }
                         }
                         is FirTypeParameterSymbol -> {
-                            assert(typeRef.qualifier.size == 1)
+                            assert(qualifier.size == 1)
                             symbol
                         }
                         else -> error("!")
@@ -89,7 +92,7 @@ class FirTypeResolverImpl(private val session: FirSession) : FirTypeResolver() {
                 }
 
                 // TODO: Imports
-                val resultSymbol: FirBasedSymbol<*>? = resolvedSymbol ?: qualifierResolver.resolveSymbol(typeRef.qualifier)
+                val resultSymbol: FirBasedSymbol<*>? = resolvedSymbol ?: qualifierResolver.resolveSymbol(qualifier)
                 resultSymbol to substitutor
             }
 
@@ -101,6 +104,31 @@ class FirTypeResolverImpl(private val session: FirSession) : FirTypeResolver() {
         }
     }
 
+    private fun resolveLocalClassChain(symbol: FirClassLikeSymbol<*>, qualifier: List<FirQualifierPart>): FirRegularClassSymbol? {
+        if (symbol !is FirRegularClassSymbol || !symbol.isLocal) {
+            return null
+        }
+
+        fun resolveLocalClassChain(classSymbol: FirRegularClassSymbol, qualifierIndex: Int): FirRegularClassSymbol? {
+            if (qualifierIndex == qualifier.size) {
+                return classSymbol
+            }
+
+            val qualifierName = qualifier[qualifierIndex].name
+            for (declarationSymbol in classSymbol.declarationSymbols) {
+                if (declarationSymbol is FirRegularClassSymbol) {
+                    if (declarationSymbol.toLookupTag().name == qualifierName) {
+                        return resolveLocalClassChain(declarationSymbol, qualifierIndex + 1)
+                    }
+                }
+            }
+
+            return null
+        }
+
+        return resolveLocalClassChain(symbol, 1)
+    }
+
     @OptIn(SymbolInternals::class)
     private fun FirQualifierResolver.resolveEnumEntrySymbol(
         qualifier: List<FirQualifierPart>,

compiler/testData/diagnostics/tests/generics/capturedParameters/uncheckedCast.fir.kt

@@ -18,11 +18,11 @@ fun <E> foo(x: Any, y: Any) : Any {
     }
 
     // bare type
-    if (y is <!UNRESOLVED_REFERENCE!>Outer.Inner<!>) {
+    if (y is <!NO_TYPE_ARGUMENTS_ON_RHS!>Outer.Inner<!>) {
         return y
     }
 
-    y as <!UNRESOLVED_REFERENCE!>Outer<*>.Inner<!>
+    y as Outer<*>.Inner
 
     return C()
 }

compiler/testData/diagnostics/tests/regressions/LocalClassReferenceChain.kt

@@ -0,0 +1,15 @@
+// FIR_IDENTICAL
+// KT-47135
+
+fun test2() {
+    class LocalA {
+        inner class LocalB {
+            inner class LocalC {
+            }
+        }
+    }
+
+    fun LocalA.LocalB.blah() {
+        val c: LocalA.LocalB.LocalC = LocalC()
+    }
+}

compiler/testData/diagnostics/tests/regressions/LocalClassReferenceChain.txt

@@ -0,0 +1,3 @@
+package
+
+public fun test2(): kotlin.Unit

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

@@ -24095,6 +24095,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
                 runTest("compiler/testData/diagnostics/tests/regressions/kt9808.kt");
             }
 
+            @Test
+            @TestMetadata("LocalClassReferenceChain.kt")
+            public void testLocalClassReferenceChain() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/regressions/LocalClassReferenceChain.kt");
+            }
+
             @Test
             @TestMetadata("noThis.kt")
             public void testNoThis() throws Exception {