[FIR] Support of ACTUAL_FUNCTION_WITH_DEFAULT_ARGUMENTS diagnostic

^KT-56522 Fixed

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

@@ -22,38 +22,53 @@ object FirActualDeclarationChecker : FirBasicDeclarationChecker() {
         if (declaration !is FirMemberDeclaration || !declaration.isActual) return
 
         if (declaration is FirCallableDeclaration) {
-            val actualFunctionSymbol = declaration.symbol
+            if (declaration is FirFunction) {
-            val expectFunctionSymbol = actualFunctionSymbol.getSingleCompatibleExpectForActualOrNull() as? FirCallableSymbol ?: return
+                checkActualFunctionWithDefaultArguments(declaration, reporter, context)
+            }
+            checkReturnTypes(declaration, context, reporter)
+        }
+    }
 
-            val expectTypeParameters = expectFunctionSymbol.getContainingClassSymbol(expectFunctionSymbol.moduleData.session)
+    private fun checkActualFunctionWithDefaultArguments(function: FirFunction, reporter: DiagnosticReporter, context: CheckerContext) {
-                ?.typeParameterSymbols.orEmpty()
+        for (valueParameter in function.valueParameters) {
-            val actualClassTypeParameters = actualFunctionSymbol.getContainingClassSymbol(context.session)?.typeParameterSymbols.orEmpty()
+            if (valueParameter.defaultValue != null) {
-            val parentSubstitutor =
+                reporter.reportOn(valueParameter.source, FirErrors.ACTUAL_FUNCTION_WITH_DEFAULT_ARGUMENTS, context)
-                createExpectActualTypeParameterSubstitutor(expectTypeParameters, actualClassTypeParameters, context.session)
-
-            val substitutor = createExpectActualTypeParameterSubstitutor(
-                expectFunctionSymbol.typeParameterSymbols,
-                actualFunctionSymbol.typeParameterSymbols,
-                context.session,
-                parentSubstitutor
-            )
-
-            if (!areCompatibleExpectActualTypes(
-                    substitutor.substituteOrSelf(expectFunctionSymbol.resolvedReturnType.type),
-                    actualFunctionSymbol.resolvedReturnType.type,
-                    expectFunctionSymbol.moduleData.session,
-                    context.session
-                )
-            ) {
-                @Suppress("UNCHECKED_CAST")
-                reporter.reportOn(
-                    declaration.source,
-                    FirErrors.ACTUAL_WITHOUT_EXPECT,
-                    actualFunctionSymbol,
-                    actualFunctionSymbol.expectForActual as Map<ExpectActualCompatibility.Incompatible<FirBasedSymbol<*>>, Collection<FirBasedSymbol<*>>>,
-                    context
-                )
             }
         }
     }
+
+    private fun checkReturnTypes(callableDeclaration: FirCallableDeclaration, context: CheckerContext, reporter: DiagnosticReporter) {
+        val actualFunctionSymbol = callableDeclaration.symbol
+        val expectFunctionSymbol = actualFunctionSymbol.getSingleCompatibleExpectForActualOrNull() as? FirCallableSymbol ?: return
+
+        val expectTypeParameters = expectFunctionSymbol.getContainingClassSymbol(expectFunctionSymbol.moduleData.session)
+            ?.typeParameterSymbols.orEmpty()
+        val actualClassTypeParameters = actualFunctionSymbol.getContainingClassSymbol(context.session)?.typeParameterSymbols.orEmpty()
+        val parentSubstitutor =
+            createExpectActualTypeParameterSubstitutor(expectTypeParameters, actualClassTypeParameters, context.session)
+
+        val substitutor = createExpectActualTypeParameterSubstitutor(
+            expectFunctionSymbol.typeParameterSymbols,
+            actualFunctionSymbol.typeParameterSymbols,
+            context.session,
+            parentSubstitutor
+        )
+
+        if (!areCompatibleExpectActualTypes(
+                substitutor.substituteOrSelf(expectFunctionSymbol.resolvedReturnType.type),
+                actualFunctionSymbol.resolvedReturnType.type,
+                expectFunctionSymbol.moduleData.session,
+                context.session
+            )
+        ) {
+            @Suppress("UNCHECKED_CAST")
+            reporter.reportOn(
+                callableDeclaration.source,
+                FirErrors.ACTUAL_WITHOUT_EXPECT,
+                actualFunctionSymbol,
+                actualFunctionSymbol.expectForActual as Map<ExpectActualCompatibility.Incompatible<FirBasedSymbol<*>>, Collection<FirBasedSymbol<*>>>,
+                context
+            )
+        }
+    }
 }

compiler/testData/diagnostics/tests/multiplatform/defaultArguments/constructor.fir.kt

@@ -1,22 +0,0 @@
-// MODULE: m1-common
-// FILE: common.kt
-
-expect class Ok(x: Int, y: String = "")
-
-expect class FailX(x: Int, y: String = "")
-
-expect class FailY(x: Int, y: String = "")
-
-fun test() {
-    Ok(42)
-    Ok(42, "OK")
-}
-
-// MODULE: m2-jvm()()(m1-common)
-// FILE: jvm.kt
-
-actual class Ok actual constructor(x: Int, y: String)
-
-actual class FailX actual constructor(x: Int = 0, y: String)
-
-actual class FailY actual constructor(x: Int, y: String = "")

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

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // MODULE: m1-common
 // FILE: common.kt
 

compiler/testData/diagnostics/tests/multiplatform/defaultArguments/expectedDeclaresDefaultArguments.fir.kt

@@ -1,40 +0,0 @@
-// MODULE: m1-common
-// FILE: common.kt
-
-expect fun ok(x: Int, y: String = "")
-
-expect fun failX(x: Int, y: String = "")
-
-expect fun failY(x: Int, y: String = "")
-
-expect open class Foo {
-    fun ok(x: Int, y: String = "")
-
-    fun failX(x: Int, y: String = "")
-
-    fun failY(x: Int, y: String = "")
-}
-
-fun test(foo: Foo) {
-    ok(42)
-    ok(42, "OK")
-    foo.ok(42)
-    foo.ok(42, "OK")
-}
-
-// MODULE: m2-jvm()()(m1-common)
-// FILE: jvm.kt
-
-actual fun ok(x: Int, y: String) {}
-
-actual fun failX(x: Int = 0, y: String) {}
-
-actual fun failY(x: Int, y: String = "") {}
-
-actual open class Foo {
-    actual fun ok(x: Int, y: String) {}
-
-    actual fun failX(x: Int = 0, y: String) {}
-
-    actual fun failY(x: Int, y: String = "") {}
-}

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

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // MODULE: m1-common
 // FILE: common.kt
 

compiler/testData/diagnostics/tests/multiplatform/defaultArguments/expectedInheritsDefaultArguments.fir.kt

@@ -30,7 +30,7 @@ fun test(foo: Foo, bar: Bar) {
 actual class Bar : Foo {
     actual override fun ok(x: Int, y: String) {}
 
-    actual override fun failX(x: Int = 0, y: String) {}
+    actual override fun failX(<!ACTUAL_FUNCTION_WITH_DEFAULT_ARGUMENTS!>x: Int = 0<!>, y: String) {}
 
-    actual override fun failY(x: Int, y: String = "") {}
+    actual override fun failY(x: Int, <!ACTUAL_FUNCTION_WITH_DEFAULT_ARGUMENTS!>y: String = ""<!>) {}
 }