[FE] Fix checker of DEFAULT_ARGUMENTS_IN_EXPECT_WITH_ACTUAL_TYPEALIAS

...not reporting on companion object members as well as other
nested classes.

Annotation classes are accepted because this is how it already worked,
see other tests, for example `annotationsViaActualTypeAlias.kt`.

Test for nested annotation classes will be added in subsequent commit,
because it currently will fail in test
`TreeCompareTest.testCompareDiagnostics` because light-tree2fir
produces different tree due to a bug when converting properties
from expect primary constructor. See subsequent commit for a fix.

Review: KT-MR-12107

^KT-61784

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

@@ -982,6 +982,12 @@ public class FirOldFrontendMPPDiagnosticsWithLightTreeTestGenerated extends Abst
             runTest("compiler/testData/diagnostics/tests/multiplatform/defaultArguments/annotationsViaActualTypeAlias2.kt");
         }
 
+        @Test
+        @TestMetadata("companionMethodViaActualTypealias.kt")
+        public void testCompanionMethodViaActualTypealias() throws Exception {
+            runTest("compiler/testData/diagnostics/tests/multiplatform/defaultArguments/companionMethodViaActualTypealias.kt");
+        }
+
         @Test
         @TestMetadata("constructor.kt")
         public void testConstructor() throws Exception {
@@ -1029,6 +1035,12 @@ public class FirOldFrontendMPPDiagnosticsWithLightTreeTestGenerated extends Abst
         public void testMethodDefaultArgsViaActualTypealias_oldLanguageVersion() throws Exception {
             runTest("compiler/testData/diagnostics/tests/multiplatform/defaultArguments/methodDefaultArgsViaActualTypealias_oldLanguageVersion.kt");
         }
+
+        @Test
+        @TestMetadata("nestedClassMethodsViaActualTypealias.kt")
+        public void testNestedClassMethodsViaActualTypealias() throws Exception {
+            runTest("compiler/testData/diagnostics/tests/multiplatform/defaultArguments/nestedClassMethodsViaActualTypealias.kt");
+        }
     }
 
     @Nested

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

@@ -982,6 +982,12 @@ public class FirOldFrontendMPPDiagnosticsWithPsiTestGenerated extends AbstractFi
             runTest("compiler/testData/diagnostics/tests/multiplatform/defaultArguments/annotationsViaActualTypeAlias2.kt");
         }
 
+        @Test
+        @TestMetadata("companionMethodViaActualTypealias.kt")
+        public void testCompanionMethodViaActualTypealias() throws Exception {
+            runTest("compiler/testData/diagnostics/tests/multiplatform/defaultArguments/companionMethodViaActualTypealias.kt");
+        }
+
         @Test
         @TestMetadata("constructor.kt")
         public void testConstructor() throws Exception {
@@ -1029,6 +1035,12 @@ public class FirOldFrontendMPPDiagnosticsWithPsiTestGenerated extends AbstractFi
         public void testMethodDefaultArgsViaActualTypealias_oldLanguageVersion() throws Exception {
             runTest("compiler/testData/diagnostics/tests/multiplatform/defaultArguments/methodDefaultArgsViaActualTypealias_oldLanguageVersion.kt");
         }
+
+        @Test
+        @TestMetadata("nestedClassMethodsViaActualTypealias.kt")
+        public void testNestedClassMethodsViaActualTypealias() throws Exception {
+            runTest("compiler/testData/diagnostics/tests/multiplatform/defaultArguments/nestedClassMethodsViaActualTypealias.kt");
+        }
     }
 
     @Nested

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirExpectActualDeclarationChecker.kt

@@ -25,6 +25,7 @@ import org.jetbrains.kotlin.fir.expressions.FirAnnotation
 import org.jetbrains.kotlin.fir.languageVersionSettings
 import org.jetbrains.kotlin.fir.scopes.collectAllFunctions
 import org.jetbrains.kotlin.fir.scopes.getDeclaredConstructors
+import org.jetbrains.kotlin.fir.scopes.getSingleClassifier
 import org.jetbrains.kotlin.fir.scopes.impl.declaredMemberScope
 import org.jetbrains.kotlin.fir.symbols.FirBasedSymbol
 import org.jetbrains.kotlin.fir.symbols.SymbolInternals
@@ -236,16 +237,9 @@ object FirExpectActualDeclarationChecker : FirBasicDeclarationChecker() {
         reporter: DiagnosticReporter,
     ) {
         if (!context.languageVersionSettings.supportsFeature(LanguageFeature.MultiplatformRestrictions)) return
-        if (expectSymbol !is FirClassSymbol ||
-            actualSymbol !is FirTypeAliasSymbol ||
-            expectSymbol.classKind == ClassKind.ANNOTATION_CLASS
-        ) return
-
-        val membersWithDefaultValueParameters =
-            expectSymbol.declaredMemberScope(expectSymbol.moduleData.session, memberRequiredPhase = null)
-                .run { collectAllFunctions() + getDeclaredConstructors() }
-                .filter { it.valueParameterSymbols.any(FirValueParameterSymbol::hasDefaultValue) }
+        if (expectSymbol !is FirClassSymbol || actualSymbol !is FirTypeAliasSymbol) return
 
+        val membersWithDefaultValueParameters = getMembersWithDefaultValueParametersUnlessAnnotation(expectSymbol)
         if (membersWithDefaultValueParameters.isEmpty()) return
 
         reporter.reportOn(
@@ -257,6 +251,31 @@ object FirExpectActualDeclarationChecker : FirBasicDeclarationChecker() {
         )
     }
 
+    private fun getMembersWithDefaultValueParametersUnlessAnnotation(classSymbol: FirClassSymbol<*>): List<FirFunctionSymbol<*>> {
+        val result = mutableListOf<FirFunctionSymbol<*>>()
+
+        fun collectFunctions(classSymbol: FirClassSymbol<*>) {
+            if (classSymbol.classKind == ClassKind.ANNOTATION_CLASS) {
+                return
+            }
+            val memberScope = classSymbol.declaredMemberScope(classSymbol.moduleData.session, memberRequiredPhase = null)
+            val functionsAndConstructors = memberScope
+                .run { collectAllFunctions() + getDeclaredConstructors() }
+
+            functionsAndConstructors.filterTo(result) { it.valueParameterSymbols.any(FirValueParameterSymbol::hasDefaultValue) }
+
+            val nestedClasses = memberScope.getClassifierNames()
+                .mapNotNull { memberScope.getSingleClassifier(it) as? FirClassSymbol<*> }
+
+            for (nestedClassSymbol in nestedClasses) {
+                collectFunctions(nestedClassSymbol)
+            }
+        }
+
+        collectFunctions(classSymbol)
+        return result
+    }
+
     private fun checkAnnotationsMatch(
         expectSymbol: FirBasedSymbol<*>,
         actualSymbol: FirBasedSymbol<*>,

compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/ExpectedActualDeclarationChecker.kt

@@ -244,18 +244,9 @@ class ExpectedActualDeclarationChecker(
         context: DeclarationCheckerContext,
     ) {
         if (!context.languageVersionSettings.supportsFeature(LanguageFeature.MultiplatformRestrictions)) return
-        if (expectDescriptor !is ClassDescriptor ||
-            actualDeclaration !is KtTypeAlias ||
-            expectDescriptor.kind == ClassKind.ANNOTATION_CLASS
-        ) return
-
-        val members = expectDescriptor.constructors + expectDescriptor.unsubstitutedMemberScope
-            .getContributedDescriptors(DescriptorKindFilter.FUNCTIONS)
-            .filterIsInstance<FunctionDescriptor>()
-
-        val membersWithDefaultValueParameters = members
-            .filter { it.valueParameters.any { p -> p.declaresDefaultValue() }}
+        if (expectDescriptor !is ClassDescriptor || actualDeclaration !is KtTypeAlias) return
 
+        val membersWithDefaultValueParameters = getMembersWithDefaultValueParametersUnlessAnnotation(expectDescriptor)
         if (membersWithDefaultValueParameters.isEmpty()) return
 
         context.trace.report(
@@ -267,6 +258,32 @@ class ExpectedActualDeclarationChecker(
         )
     }
 
+    private fun getMembersWithDefaultValueParametersUnlessAnnotation(classDescriptor: ClassDescriptor): List<FunctionDescriptor> {
+        val result = mutableListOf<FunctionDescriptor>()
+
+        fun collectFunctions(classDescriptor: ClassDescriptor) {
+            if (classDescriptor.kind == ClassKind.ANNOTATION_CLASS) {
+                return
+            }
+            val functionsAndConstructors = classDescriptor.constructors + classDescriptor.unsubstitutedMemberScope
+                .getContributedDescriptors(DescriptorKindFilter.FUNCTIONS)
+                .filterIsInstance<FunctionDescriptor>()
+
+            functionsAndConstructors.filterTo(result) { it.valueParameters.any { p -> p.declaresDefaultValue() } }
+
+            val nestedClasses = classDescriptor.unsubstitutedMemberScope
+                .getContributedDescriptors(DescriptorKindFilter.CLASSIFIERS)
+                .filterIsInstance<ClassDescriptor>()
+
+            for (nestedClass in nestedClasses) {
+                collectFunctions(nestedClass)
+            }
+        }
+
+        collectFunctions(classDescriptor)
+        return result
+    }
+
     private fun MemberDescriptor.hasNoActualWithDiagnostic(
         compatibility: Map<ExpectActualCompatibility<MemberDescriptor>, List<MemberDescriptor>>
     ): Boolean {

compiler/testData/diagnostics/tests/multiplatform/defaultArguments/companionMethodViaActualTypealias.kt

@@ -0,0 +1,18 @@
+// FIR_IDENTICAL
+// MODULE: m1-common
+// FILE: common.kt
+expect class DefaultArgsInCompanion {
+    companion object {
+        fun foo(p: String = "")
+    }
+}
+
+// MODULE: m2-jvm()()(m1-common)
+// FILE: jvm.kt
+class DefaultArgsInCompanionImpl {
+    companion object {
+        fun foo(p: String) {}
+    }
+}
+
+<!DEFAULT_ARGUMENTS_IN_EXPECT_WITH_ACTUAL_TYPEALIAS!>actual typealias DefaultArgsInCompanion = DefaultArgsInCompanionImpl<!>

compiler/testData/diagnostics/tests/multiplatform/defaultArguments/nestedClassMethodsViaActualTypealias.kt

@@ -0,0 +1,18 @@
+// FIR_IDENTICAL
+// MODULE: m1-common
+// FILE: common.kt
+expect class DefaultArgsInNestedClass {
+    class Nested {
+        fun foo(p: String = "")
+    }
+}
+
+// MODULE: m2-jvm()()(m1-common)
+// FILE: jvm.kt
+class DefaultArgsInNestedClassImpl {
+    class Nested {
+        fun foo(p: String) {}
+    }
+}
+
+<!DEFAULT_ARGUMENTS_IN_EXPECT_WITH_ACTUAL_TYPEALIAS!>actual typealias DefaultArgsInNestedClass = DefaultArgsInNestedClassImpl<!>

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

@@ -23977,6 +23977,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
                     runTest("compiler/testData/diagnostics/tests/multiplatform/defaultArguments/annotationsViaActualTypeAlias2.kt");
                 }
 
+                @Test
+                @TestMetadata("companionMethodViaActualTypealias.kt")
+                public void testCompanionMethodViaActualTypealias() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/multiplatform/defaultArguments/companionMethodViaActualTypealias.kt");
+                }
+
                 @Test
                 @TestMetadata("constructor.kt")
                 public void testConstructor() throws Exception {
@@ -24024,6 +24030,12 @@ public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
                 public void testMethodDefaultArgsViaActualTypealias_oldLanguageVersion() throws Exception {
                     runTest("compiler/testData/diagnostics/tests/multiplatform/defaultArguments/methodDefaultArgsViaActualTypealias_oldLanguageVersion.kt");
                 }
+
+                @Test
+                @TestMetadata("nestedClassMethodsViaActualTypealias.kt")
+                public void testNestedClassMethodsViaActualTypealias() throws Exception {
+                    runTest("compiler/testData/diagnostics/tests/multiplatform/defaultArguments/nestedClassMethodsViaActualTypealias.kt");
+                }
             }
 
             @Nested