[FIR2IR] Properly set isAssignable flag for parameters of tailrec functions

^KT-63973 Fixed

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

@@ -55196,6 +55196,12 @@ public class LLFirBlackBoxCodegenBasedTestGenerated extends AbstractLLFirBlackBo
             runTest("compiler/testData/codegen/box/vararg/varargInJava.kt");
         }
 
+        @Test
+        @TestMetadata("varargInTailrec.kt")
+        public void testVarargInTailrec() throws Exception {
+            runTest("compiler/testData/codegen/box/vararg/varargInTailrec.kt");
+        }
+
         @Test
         @TestMetadata("varargsAndFunctionLiterals.kt")
         public void testVarargsAndFunctionLiterals() throws Exception {

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

@@ -55196,6 +55196,12 @@ public class LLFirReversedBlackBoxCodegenBasedTestGenerated extends AbstractLLFi
             runTest("compiler/testData/codegen/box/vararg/varargInJava.kt");
         }
 
+        @Test
+        @TestMetadata("varargInTailrec.kt")
+        public void testVarargInTailrec() throws Exception {
+            runTest("compiler/testData/codegen/box/vararg/varargInTailrec.kt");
+        }
+
         @Test
         @TestMetadata("varargsAndFunctionLiterals.kt")
         public void testVarargsAndFunctionLiterals() throws Exception {

compiler/fir/fir2ir/jvm-backend/src/org/jetbrains/kotlin/fir/backend/jvm/JvmFir2IrExtensions.kt

@@ -35,6 +35,7 @@ class JvmFir2IrExtensions(
     private val irDeserializer: JvmIrDeserializer,
     private val mangler: KotlinMangler.IrMangler,
 ) : Fir2IrExtensions, JvmGeneratorExtensions {
+    override val parametersAreAssignable: Boolean get() = true
     override val externalOverridabilityConditions: List<IrExternalOverridabilityCondition> = emptyList() // TODO: KT-61370, KT-61804
     override val classNameOverride: MutableMap<IrClass, JvmClassName> = mutableMapOf()
     override val cachedFields = CachedFieldsForObjectInstances(IrFactoryImpl, configuration.languageVersionSettings)

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/ConversionUtils.kt

@@ -562,6 +562,7 @@ internal fun IrDeclarationParent.declareThisReceiverParameter(
     endOffset: Int = this.endOffset,
     name: Name = SpecialNames.THIS,
     explicitReceiver: FirReceiverParameter? = null,
+    isAssignable: Boolean = false
 ): IrValueParameter {
     return symbolTable.irFactory.createValueParameter(
         startOffset = startOffset,
@@ -569,7 +570,7 @@ internal fun IrDeclarationParent.declareThisReceiverParameter(
         origin = thisOrigin,
         name = name,
         type = thisType,
-        isAssignable = false,
+        isAssignable = isAssignable,
         symbol = IrValueParameterSymbolImpl(),
         index = UNDEFINED_PARAMETER_INDEX,
         varargElementType = null,

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrExtensions.kt

@@ -16,6 +16,12 @@ import org.jetbrains.kotlin.ir.util.SymbolTable
 
 interface Fir2IrExtensions {
     val irNeedsDeserialization: Boolean
+
+    /**
+     * Determines if parameters of tailrec functions should be generated with isAssignable = true
+     */
+    val parametersAreAssignable: Boolean
+
     val externalOverridabilityConditions: List<IrExternalOverridabilityCondition>
 
     fun generateOrGetFacadeClass(declaration: IrMemberWithContainerSource, components: Fir2IrComponents): IrClass?
@@ -35,6 +41,9 @@ interface Fir2IrExtensions {
         override val irNeedsDeserialization: Boolean
             get() = false
 
+        override val parametersAreAssignable: Boolean
+            get() = false
+
         override val externalOverridabilityConditions: List<IrExternalOverridabilityCondition> = emptyList()
         override fun generateOrGetFacadeClass(declaration: IrMemberWithContainerSource, components: Fir2IrComponents): IrClass? = null
         override fun deserializeToplevelClass(irClass: IrClass, components: Fir2IrComponents): Boolean = false

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/generators/Fir2IrCallableDeclarationsGenerator.kt

@@ -705,6 +705,7 @@ class Fir2IrCallableDeclarationsGenerator(val components: Fir2IrComponents) : Fi
                         endOffset = endOffset,
                         name = name,
                         explicitReceiver = receiver,
+                        isAssignable = function.shouldParametersBeAssignable()
                     )
                 }
             }
@@ -750,7 +751,7 @@ class Fir2IrCallableDeclarationsGenerator(val components: Fir2IrComponents) : Fi
                 origin = origin,
                 name = valueParameter.name,
                 type = type,
-                isAssignable = false,
+                isAssignable = valueParameter.containingFunctionSymbol.fir.shouldParametersBeAssignable(),
                 symbol = IrValueParameterSymbolImpl(),
                 index = index,
                 varargElementType = valueParameter.varargElementType?.toIrType(typeOrigin),
@@ -1026,3 +1027,8 @@ internal fun IrDeclarationParent?.isExternalParent(): Boolean {
     }
     return this is Fir2IrLazyClass || this is IrExternalPackageFragment
 }
+
+context(Fir2IrComponents)
+internal fun FirCallableDeclaration?.shouldParametersBeAssignable(): Boolean {
+    return extensions.parametersAreAssignable && this?.isTailRec == true
+}

compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirLightTreeBlackBoxCodegenTestGenerated.java

@@ -54597,6 +54597,12 @@ public class FirLightTreeBlackBoxCodegenTestGenerated extends AbstractFirLightTr
             runTest("compiler/testData/codegen/box/vararg/varargInJava.kt");
         }
 
+        @Test
+        @TestMetadata("varargInTailrec.kt")
+        public void testVarargInTailrec() throws Exception {
+            runTest("compiler/testData/codegen/box/vararg/varargInTailrec.kt");
+        }
+
         @Test
         @TestMetadata("varargsAndFunctionLiterals.kt")
         public void testVarargsAndFunctionLiterals() throws Exception {

compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirLightTreeBlackBoxCodegenWithIrFakeOverrideGeneratorTestGenerated.java

@@ -54597,6 +54597,12 @@ public class FirLightTreeBlackBoxCodegenWithIrFakeOverrideGeneratorTestGenerated
             runTest("compiler/testData/codegen/box/vararg/varargInJava.kt");
         }
 
+        @Test
+        @TestMetadata("varargInTailrec.kt")
+        public void testVarargInTailrec() throws Exception {
+            runTest("compiler/testData/codegen/box/vararg/varargInTailrec.kt");
+        }
+
         @Test
         @TestMetadata("varargsAndFunctionLiterals.kt")
         public void testVarargsAndFunctionLiterals() throws Exception {

compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/codegen/FirPsiBlackBoxCodegenTestGenerated.java

@@ -54597,6 +54597,12 @@ public class FirPsiBlackBoxCodegenTestGenerated extends AbstractFirPsiBlackBoxCo
             runTest("compiler/testData/codegen/box/vararg/varargInJava.kt");
         }
 
+        @Test
+        @TestMetadata("varargInTailrec.kt")
+        public void testVarargInTailrec() throws Exception {
+            runTest("compiler/testData/codegen/box/vararg/varargInTailrec.kt");
+        }
+
         @Test
         @TestMetadata("varargsAndFunctionLiterals.kt")
         public void testVarargsAndFunctionLiterals() throws Exception {

compiler/testData/codegen/box/vararg/varargInTailrec.kt

@@ -0,0 +1,19 @@
+// ISSUE: KT-63973
+// WITH_STDLIB
+
+tailrec fun <T> foo(vararg items: String, fn: (String) -> T): T = when (items.size) {
+    0 -> fn("")
+    else -> foo(*items.drop(1).toTypedArray()) {
+        fn(items.first())
+    }
+}
+
+fun box(): String {
+    val result = buildString {
+        foo("abcde") { append(it) }
+    }
+    if (result != "abcde") {
+        return "Fail: $result"
+    }
+    return "OK"
+}

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

@@ -50709,6 +50709,12 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             runTest("compiler/testData/codegen/box/vararg/varargInJava.kt");
         }
 
+        @Test
+        @TestMetadata("varargInTailrec.kt")
+        public void testVarargInTailrec() throws Exception {
+            runTest("compiler/testData/codegen/box/vararg/varargInTailrec.kt");
+        }
+
         @Test
         @TestMetadata("varargsAndFunctionLiterals.kt")
         public void testVarargsAndFunctionLiterals() throws Exception {

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

@@ -53949,6 +53949,12 @@ public class IrBlackBoxCodegenTestGenerated extends AbstractIrBlackBoxCodegenTes
             runTest("compiler/testData/codegen/box/vararg/varargInJava.kt");
         }
 
+        @Test
+        @TestMetadata("varargInTailrec.kt")
+        public void testVarargInTailrec() throws Exception {
+            runTest("compiler/testData/codegen/box/vararg/varargInTailrec.kt");
+        }
+
         @Test
         @TestMetadata("varargsAndFunctionLiterals.kt")
         public void testVarargsAndFunctionLiterals() throws Exception {

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

@@ -53949,6 +53949,12 @@ public class IrBlackBoxCodegenWithIrInlinerTestGenerated extends AbstractIrBlack
             runTest("compiler/testData/codegen/box/vararg/varargInJava.kt");
         }
 
+        @Test
+        @TestMetadata("varargInTailrec.kt")
+        public void testVarargInTailrec() throws Exception {
+            runTest("compiler/testData/codegen/box/vararg/varargInTailrec.kt");
+        }
+
         @Test
         @TestMetadata("varargsAndFunctionLiterals.kt")
         public void testVarargsAndFunctionLiterals() throws Exception {

compiler/tests-gen/org/jetbrains/kotlin/codegen/LightAnalysisModeTestGenerated.java

@@ -43626,6 +43626,11 @@ public class LightAnalysisModeTestGenerated extends AbstractLightAnalysisModeTes
             runTest("compiler/testData/codegen/box/vararg/varargInJava.kt");
         }
 
+        @TestMetadata("varargInTailrec.kt")
+        public void testVarargInTailrec() throws Exception {
+            runTest("compiler/testData/codegen/box/vararg/varargInTailrec.kt");
+        }
+
         @TestMetadata("varargsAndFunctionLiterals.kt")
         public void testVarargsAndFunctionLiterals() throws Exception {
             runTest("compiler/testData/codegen/box/vararg/varargsAndFunctionLiterals.kt");

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/fir/FirJsCodegenBoxTestGenerated.java

@@ -37923,6 +37923,12 @@ public class FirJsCodegenBoxTestGenerated extends AbstractFirJsCodegenBoxTest {
             runTest("compiler/testData/codegen/box/vararg/varargInFunParam.kt");
         }
 
+        @Test
+        @TestMetadata("varargInTailrec.kt")
+        public void testVarargInTailrec() throws Exception {
+            runTest("compiler/testData/codegen/box/vararg/varargInTailrec.kt");
+        }
+
         @Test
         @TestMetadata("varargsAndFunctionLiterals.kt")
         public void testVarargsAndFunctionLiterals() throws Exception {

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/fir/FirJsES6CodegenBoxTestGenerated.java

@@ -37923,6 +37923,12 @@ public class FirJsES6CodegenBoxTestGenerated extends AbstractFirJsES6CodegenBoxT
             runTest("compiler/testData/codegen/box/vararg/varargInFunParam.kt");
         }
 
+        @Test
+        @TestMetadata("varargInTailrec.kt")
+        public void testVarargInTailrec() throws Exception {
+            runTest("compiler/testData/codegen/box/vararg/varargInTailrec.kt");
+        }
+
         @Test
         @TestMetadata("varargsAndFunctionLiterals.kt")
         public void testVarargsAndFunctionLiterals() throws Exception {

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/IrJsCodegenBoxTestGenerated.java

@@ -37377,6 +37377,12 @@ public class IrJsCodegenBoxTestGenerated extends AbstractIrJsCodegenBoxTest {
             runTest("compiler/testData/codegen/box/vararg/varargInFunParam.kt");
         }
 
+        @Test
+        @TestMetadata("varargInTailrec.kt")
+        public void testVarargInTailrec() throws Exception {
+            runTest("compiler/testData/codegen/box/vararg/varargInTailrec.kt");
+        }
+
         @Test
         @TestMetadata("varargsAndFunctionLiterals.kt")
         public void testVarargsAndFunctionLiterals() throws Exception {

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/IrJsES6CodegenBoxTestGenerated.java

@@ -37377,6 +37377,12 @@ public class IrJsES6CodegenBoxTestGenerated extends AbstractIrJsES6CodegenBoxTes
             runTest("compiler/testData/codegen/box/vararg/varargInFunParam.kt");
         }
 
+        @Test
+        @TestMetadata("varargInTailrec.kt")
+        public void testVarargInTailrec() throws Exception {
+            runTest("compiler/testData/codegen/box/vararg/varargInTailrec.kt");
+        }
+
         @Test
         @TestMetadata("varargsAndFunctionLiterals.kt")
         public void testVarargsAndFunctionLiterals() throws Exception {

kotlin-native/backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/Fir2Ir.kt

@@ -53,6 +53,7 @@ internal val KlibFactories = KlibMetadataFactories(::KonanBuiltIns, DynamicTypeD
 
 internal object NativeFir2IrExtensions : Fir2IrExtensions {
     override val irNeedsDeserialization = false
+    override val parametersAreAssignable: Boolean get() = false
     override val externalOverridabilityConditions = listOf(IrObjCOverridabilityCondition)
     override fun generateOrGetFacadeClass(declaration: IrMemberWithContainerSource, components: Fir2IrComponents) = null
     override fun deserializeToplevelClass(irClass: IrClass, components: Fir2IrComponents) = false

native/native.tests/tests-gen/org/jetbrains/kotlin/konan/test/blackbox/FirNativeCodegenBoxTestGenerated.java

@@ -41696,6 +41696,12 @@ public class FirNativeCodegenBoxTestGenerated extends AbstractNativeCodegenBoxTe
                 runTest("compiler/testData/codegen/box/vararg/varargInFunParam.kt");
             }
 
+            @Test
+            @TestMetadata("varargInTailrec.kt")
+            public void testVarargInTailrec() throws Exception {
+                runTest("compiler/testData/codegen/box/vararg/varargInTailrec.kt");
+            }
+
             @Test
             @TestMetadata("varargsAndFunctionLiterals.kt")
             public void testVarargsAndFunctionLiterals() throws Exception {

native/native.tests/tests-gen/org/jetbrains/kotlin/konan/test/blackbox/FirNativeCodegenBoxTestNoPLGenerated.java

@@ -42760,6 +42760,12 @@ public class FirNativeCodegenBoxTestNoPLGenerated extends AbstractNativeCodegenB
                 runTest("compiler/testData/codegen/box/vararg/varargInFunParam.kt");
             }
 
+            @Test
+            @TestMetadata("varargInTailrec.kt")
+            public void testVarargInTailrec() throws Exception {
+                runTest("compiler/testData/codegen/box/vararg/varargInTailrec.kt");
+            }
+
             @Test
             @TestMetadata("varargsAndFunctionLiterals.kt")
             public void testVarargsAndFunctionLiterals() throws Exception {

native/native.tests/tests-gen/org/jetbrains/kotlin/konan/test/blackbox/NativeCodegenBoxTestGenerated.java

@@ -40074,6 +40074,12 @@ public class NativeCodegenBoxTestGenerated extends AbstractNativeCodegenBoxTest
                 runTest("compiler/testData/codegen/box/vararg/varargInFunParam.kt");
             }
 
+            @Test
+            @TestMetadata("varargInTailrec.kt")
+            public void testVarargInTailrec() throws Exception {
+                runTest("compiler/testData/codegen/box/vararg/varargInTailrec.kt");
+            }
+
             @Test
             @TestMetadata("varargsAndFunctionLiterals.kt")
             public void testVarargsAndFunctionLiterals() throws Exception {

native/native.tests/tests-gen/org/jetbrains/kotlin/konan/test/blackbox/NativeCodegenBoxTestNoPLGenerated.java

@@ -41127,6 +41127,12 @@ public class NativeCodegenBoxTestNoPLGenerated extends AbstractNativeCodegenBoxT
                 runTest("compiler/testData/codegen/box/vararg/varargInFunParam.kt");
             }
 
+            @Test
+            @TestMetadata("varargInTailrec.kt")
+            public void testVarargInTailrec() throws Exception {
+                runTest("compiler/testData/codegen/box/vararg/varargInTailrec.kt");
+            }
+
             @Test
             @TestMetadata("varargsAndFunctionLiterals.kt")
             public void testVarargsAndFunctionLiterals() throws Exception {

wasm/wasm.tests/tests-gen/org/jetbrains/kotlin/wasm/test/FirWasmCodegenBoxTestGenerated.java

@@ -37815,6 +37815,12 @@ public class FirWasmCodegenBoxTestGenerated extends AbstractFirWasmCodegenBoxTes
             runTest("compiler/testData/codegen/box/vararg/varargInFunParam.kt");
         }
 
+        @Test
+        @TestMetadata("varargInTailrec.kt")
+        public void testVarargInTailrec() throws Exception {
+            runTest("compiler/testData/codegen/box/vararg/varargInTailrec.kt");
+        }
+
         @Test
         @TestMetadata("varargsAndFunctionLiterals.kt")
         public void testVarargsAndFunctionLiterals() throws Exception {

wasm/wasm.tests/tests-gen/org/jetbrains/kotlin/wasm/test/K1WasmCodegenBoxTestGenerated.java

@@ -37269,6 +37269,12 @@ public class K1WasmCodegenBoxTestGenerated extends AbstractK1WasmCodegenBoxTest
             runTest("compiler/testData/codegen/box/vararg/varargInFunParam.kt");
         }
 
+        @Test
+        @TestMetadata("varargInTailrec.kt")
+        public void testVarargInTailrec() throws Exception {
+            runTest("compiler/testData/codegen/box/vararg/varargInTailrec.kt");
+        }
+
         @Test
         @TestMetadata("varargsAndFunctionLiterals.kt")
         public void testVarargsAndFunctionLiterals() throws Exception {