Fix generic signature for KSuspendFunction types in bytecode

#KT-27560 Fixed

compiler/backend/src/org/jetbrains/kotlin/codegen/state/KotlinTypeMapper.java

@@ -647,7 +647,8 @@ public class KotlinTypeMapper {
         if (classDescriptor instanceof FunctionClassDescriptor) {
             FunctionClassDescriptor functionClass = (FunctionClassDescriptor) classDescriptor;
             if (functionClass.hasBigArity() ||
-                functionClass.getFunctionKind() == FunctionClassDescriptor.Kind.KFunction) {
+                functionClass.getFunctionKind() == FunctionClassDescriptor.Kind.KFunction ||
+                functionClass.getFunctionKind() == FunctionClassDescriptor.Kind.KSuspendFunction) {
                 // kotlin.reflect.KFunction{n}<P1, ..., Pn, R> is mapped to kotlin.reflect.KFunction<R> (for all n), and
                 // kotlin.Function{n}<P1, ..., Pn, R> is mapped to kotlin.jvm.functions.FunctionN<R> (for n > 22).
                 // So for these classes, we need to skip all type arguments except the very last one

compiler/testData/writeSignature/callableReference/suspendFunctionReference.kt

@@ -0,0 +1,39 @@
+interface I
+
+abstract class AbstractTest {
+    abstract fun normal(): suspend (String) -> Unit
+
+    abstract fun extension(): suspend Double.() -> Double
+
+    abstract fun bigArity(): suspend (I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I, I) -> Unit
+}
+
+class Test : AbstractTest() {
+    override fun normal() = ::suspendNormal
+
+    override fun extension() = Double::suspendExtension
+
+    override fun bigArity() = this::suspendBigArity
+
+    private suspend fun suspendNormal(s: String) {}
+
+    private suspend fun suspendBigArity(
+        p01: I, p02: I, p03: I, p04: I, p05: I, p06: I, p07: I, p08: I, p09: I, p10: I,
+        p11: I, p12: I, p13: I, p14: I, p15: I, p16: I, p17: I, p18: I, p19: I, p20: I,
+        p21: I, p22: I, p23: I, p24: I, p25: I, p26: I, p27: I, p28: I, p29: I, p30: I
+    ) {}
+}
+
+private suspend fun Double.suspendExtension(): Double = this
+
+// method: Test::normal
+// jvm signature:     ()Lkotlin/reflect/KFunction;
+// generic signature: ()Lkotlin/reflect/KFunction<Lkotlin/Unit;>;
+
+// method: Test::extension
+// jvm signature:     ()Lkotlin/reflect/KFunction;
+// generic signature: ()Lkotlin/reflect/KFunction<Ljava/lang/Double;>;
+
+// method: Test::bigArity
+// jvm signature:     ()Lkotlin/reflect/KFunction;
+// generic signature: ()Lkotlin/reflect/KFunction<Lkotlin/Unit;>;

compiler/tests/org/jetbrains/kotlin/jvm/compiler/WriteSignatureTestGenerated.java

@@ -198,6 +198,11 @@ public class WriteSignatureTestGenerated extends AbstractWriteSignatureTest {
         public void testPropertyReferenceGet() throws Exception {
             runTest("compiler/testData/writeSignature/callableReference/propertyReferenceGet.kt");
         }
+
+        @TestMetadata("suspendFunctionReference.kt")
+        public void testSuspendFunctionReference() throws Exception {
+            runTest("compiler/testData/writeSignature/callableReference/suspendFunctionReference.kt");
+        }
     }
 
     @TestMetadata("compiler/testData/writeSignature/constructor")