[LL API] Support nested type aliases in file-based declaration provider

analysis/low-level-api-fir/src/org/jetbrains/kotlin/analysis/low/level/api/fir/project/structure/FileBasedKotlinDeclarationProvider.kt

@@ -65,8 +65,7 @@ internal class FileBasedKotlinDeclarationProvider(private val kotlinFile: KtFile
     }
 
     override fun getAllTypeAliasesByClassId(classId: ClassId): Collection<KtTypeAlias> {
-        val name = classId.relativeClassName.pathSegments().singleOrNull() ?: return emptyList()
-        return getTopLevelDeclarations(classId.packageFqName, name)
+        return getClassLikeDeclarationsByClassId(classId).filterIsInstance<KtTypeAlias>().toList()
     }
 
     override fun getTopLevelKotlinClassLikeDeclarationNamesInPackage(packageFqName: FqName): Set<Name> {

analysis/low-level-api-fir/testdata/fileBasedDeclarationProvider/nestedTypeAlias.kt

@@ -0,0 +1,7 @@
+// TYPE_ALIAS: test/Foo.Bar
+
+package test
+
+class Foo {
+    typealias Bar = Foo
+}

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/FileBasedKotlinDeclarationProviderTestGenerated.java

@@ -36,6 +36,12 @@ public class FileBasedKotlinDeclarationProviderTestGenerated extends AbstractFil
         runTest("analysis/low-level-api-fir/testdata/fileBasedDeclarationProvider/local.kt");
     }
 
+    @Test
+    @TestMetadata("nestedTypeAlias.kt")
+    public void testNestedTypeAlias() throws Exception {
+        runTest("analysis/low-level-api-fir/testdata/fileBasedDeclarationProvider/nestedTypeAlias.kt");
+    }
+
     @Test
     @TestMetadata("sameNames.kt")
     public void testSameNames() throws Exception {